query: the bond which is found between water molecules such as in ice crystals is a ( n )

pos: Hydrogen bond a model system. When more molecules are present, as is the case with liquid water, more bonds are possible because the oxygen of one water molecule has two lone pairs of electrons, each of which can form a hydrogen bond with a hydrogen on another water molecule. This can repeat such that every water molecule is H-bonded with up to four other molecules, as shown in the figure (two through its two lone pairs, and two through its two hydrogen atoms). Hydrogen bonding strongly affects the crystal structure of ice, helping to create an open hexagonal lattice. The density of

pos: Hydrogen bond their laboratory, Maurice Loyal Huggins, saying, "Mr. Huggins of this laboratory in some work as yet unpublished, has used the idea of a hydrogen kernel held between two atoms as a theory in regard to certain organic compounds." A ubiquitous example of a hydrogen bond is found between water molecules. In a discrete water molecule, there are two hydrogen atoms and one oxygen atom. Two molecules of water can form a hydrogen bond between them that is to say oxygen-hydrogen bonding; the simplest case, when only two molecules are present, is called the water dimer and is often used as

pos: Hydrogen bond a model system. When more molecules are present, as is the case with liquid water, more bonds are possible because the oxygen of one water molecule has two lone pairs of electrons, each of which can form a hydrogen bond with a hydrogen on another water molecule. This can repeat such that every water molecule is H-bonded with up to four other molecules, as shown in the figure (two through its two lone pairs, and two through its two hydrogen atoms). Hydrogen bonding strongly affects the crystal structure of ice, helping to create an open hexagonal lattice. The density of

pos: Ice ice is 0.9167–0.9168 g/cm at 0 °C and standard atmospheric pressure (101,325 Pa), whereas water has a density of 0.9998–0.999863 g/cm at the same temperature and pressure. Liquid water is densest, essentially 1.00 g/cm, at 4 °C and becomes less dense as the water molecules begin to form the hexagonal crystals of ice as the freezing point is reached. This is due to hydrogen bonding dominating the intermolecular forces, which results in a packing of molecules less compact in the solid. Density of ice increases slightly with decreasing temperature and has a value of 0.9340 g/cm at −180 °C (93

pos: Selenourea substituted selenoureas. These can be synthesized using organic isoselenocyanates and secondary amines: Alternatively, a substituted carbodiimide could be used as follows: X-ray crystallographic measurements on crystals at −100 °C give average C=Se bond lengths of 1.86 Å, and 1.37 Å for C−N. Both the Se−C−N and N−C−N angles were measured at 120°, as expected for an sp-hybridized carbon. Through these same studies, the existence of Se−H hydrogen bonding in the crystal lattice—suggested from the O−H and S−H hydrogen bonding found in crystals of urea and thiourea—was confirmed. Both the shortened length of the N−C bond and the longer Se=C bond

pos: Denaturation (biochemistry) denaturation compared to the other physical denaturation methods described. Particularly in cases where rapid renaturation is desired, chemical denaturation agents can provide an ideal alternative to heating. For example, DNA strands denatured with alkaline agents such as NaOH renature as soon as phosphate buffer is added. Small, electronegative molecules such as nitrogen and oxygen, which are the primary gases in air, significantly impact the ability of surrounding molecules to participate in hydrogen bonding. These molecules compete with surrounding hydrogen bond acceptors for hydrogen bond donors, therefore acting as "hydrogen bond breakers" and weakening interactions between surrounding molecules in the environment.

neg: Ice crystals that a weather front (and rain) is approaching, as moist air is carried to high levels and freezes to ice crystals. At ambient temperature and pressure, water molecules have a V shape. The two hydrogen atoms bond to the oxygen atom at a 105° angle. Common ice crystals are symmetrical and have a hexagonal pattern. Square ice crystals form at room temperature when squeezed between two layers of graphene. The material is a new crystalline phase of ice, joining 17 others. The research derived from the earlier discovery that water vapor and liquid water could pass through laminated sheets of

neg: Grease ice depth. The supercooled water will already be encouraging the formation of small ice crystals (frazil ice) and the crystals will be mixed into the upper layer and form a surface layer. Sea ice growth in turbulent water differs from sea ice growth in calm water. In turbulent water, the ice crystals accumulate at the surface, forming a grease-ice layer composed of individual ice crystals and small irregular clumps of ice crystals. In calm water conditions, nilas, a thick elastic crust, forms at the surface, which thickens as water molecules freeze to the ice-water interface. Grease ice Grease ice is a

neg: Ice crystals graphene oxide, unlike smaller molecules such as helium. The effect is thought to be driven by the van der Waals force, which may involve more than 10,000 atmospheres of pressure. Ice crystals Ice crystals are solid ice exhibiting atomic ordering on various length scales and include hexagonal columns, hexagonal plates, dendritic crystals, and diamond dust. The hugely symmetric shapes are due to depositional growth, namely, direct deposition of water vapour onto the ice crystal. Depending on environmental temperature and humidity, ice crystals can develop from the initial hexagonal prism into numerous symmetric shapes. Possible shapes for ice crystals are columns,

neg: Mercury(II) cyanide with metal chlorates, perchlorates, nitrates, or nitrites can cause a violent explosion. At ambient temperature and ambient pressure, Hg(CN) takes the form of tetragonal crystals. These crystals are composed of nearly linear Hg(CN) molecules with a C-Hg-C bond angle of 175.0° and an Hg-C-N bond angle of 177.0° (Aylett gives slightly different values of 189° and 175°, respectively). Raman spectra show that the molecules distort at higher pressures. Between 16-20 kbar, the structure undergoes a phase transition as the Hg(II) center changes from 2- to 4-coordinate as the C"N" groups bind to neighboring Hg centers forming via Hg-N bonds. The

neg: Ice-type model the thermodynamic limit, where The values formula_14 and formula_18 are related by Several real crystals with hydrogen bonds satisfy the ice model, including ice and potassium dihydrogen phosphate (KDP). Indeed, such crystals motivated the study of ice-type models. In ice, each oxygen atom is connected by a bond to four other oxygens, and each bond contains one hydrogen atom between the terminal oxygens. The hydrogen occupies one of two symmetrically located positions, neither of which is in the middle of the bond. Pauling argued that the allowed configuration of hydrogen atoms is such that there are always exactly two hydrogens

neg: Freezer burn The condition is primarily caused by sublimation. Water evaporates at all temperatures, even from the surface of solid ice. If air adjacent to ice is cold enough and the air is dry enough, the ice does not melt and water molecules go directly from solid phase (ice) to gaseous phase (vapor) without going through a liquid phase. When the constantly vibrating water molecules in foods stored in a freezer migrate to the surface, crystals of ice outside of the solid food are formed, and some water molecules escape into the air by sublimation. The parts of meat which are deprived

neg: Ice the ice, would melt a thin layer, providing lubrication between the ice and the blade. This explanation, called "pressure melting", originated in the 19th century. It, however, did not account for skating on ice temperatures lower than , which is often skated upon. A second theory describing the coefficient of friction of ice suggested that ice molecules at the interface cannot properly bond with the molecules of the mass of ice beneath (and thus are free to move like molecules of liquid water). These molecules remain in a semi-liquid state, providing lubrication regardless of pressure against the ice exerted by

neg: Snowflake freezing point. The droplet then grows by deposition of water molecules in the air (vapor) onto the ice crystal surface where they are collected. Because water droplets are so much more numerous than the ice crystals due to their sheer abundance, the crystals are able to grow to hundreds of micrometers or millimeters in size at the expense of the water droplets. This process is known as the Wegener–Bergeron–Findeisen process. The corresponding depletion of water vapor causes the droplets to evaporate, meaning that the ice crystals grow at the droplets' expense. These large crystals are an efficient source of precipitation,

neg: Subnivean climate (near the snowpack surface) by traveling through the air spaces between ice crystals. When the water vapor reaches the top of the snowpack, it is subjected to much colder air, causing it to condense and refreeze, forming ice crystals at the top of the snowpack that can be seen as the layer of crust on top of the snow. Melt metamorphism is the deterioration of snow by melting. Melting can be stimulated by warmer ambient temperatures, rain, and fog. As snow melts, water is formed and the force of gravity pulls these molecules downward. En route to the ground, they

neg: Water of crystallization where the sample is heated strongly, and the accurate weight of a sample is plotted against the temperature. The amount of water driven off is then divided by the molar mass of water to obtain the number of molecules of water bound to the salt. Water is particularly common solvent to be found in crystals because it is small and polar. But "all" solvents can be found in some host crystals. Water is noteworthy because it is reactive, whereas other solvents such as benzene are considered to be chemically innocuous. Occasionally more than one solvent is found in a crystal,

neg: Diamond dust point even very tiny, pure water droplets will freeze. In the interior of Antarctica diamond dust is fairly common at temperatures below about . Artificial diamond dust can form from snow machines which blow ice crystals into the air. These are found at ski resorts. Diamond dust is often associated with halos, such as sun dogs, light pillars, etc. Like the ice crystals in cirrus or cirrostratus clouds, diamond dust crystals form directly as simple hexagonal ice crystals — as opposed to freezing drops — and generally form slowly. This combination results in crystals with well defined shapes - usually

neg: Water-in-water emulsion was generated when the different water-solvated molecular functional groups get segregated in an aqueous mixture consisting of polymer and liquid crystal molecules. This water-in-water emulsion consists of liquid crystals suspended as water-solvated droplets dispersed in a solution of polymer whose solvent is also water. The liquid crystal component of the emulsion is disodium cromolyn glycate (DSCG). This molecule is an anti-asthmatic drug, but also exists as a special type of liquid crystal when the concentration of DSCG is ~9-21 wt%. Unlike conventional lyotropic liquid crystals which consist of oily molecules such as 5CB, DSCG molecules are not amphiphilic, but entirely

neg: Chemical bond any particular cyanide. However, the bonds between C and N atoms in cyanide are of the "covalent" type, so that each carbon is strongly bound to "just one" nitrogen, to which it is physically much closer than it is to other carbons or nitrogens in a sodium cyanide crystal. When such crystals are melted into liquids, the ionic bonds are broken first because they are non-directional and allow the charged species to move freely. Similarly, when such salts dissolve into water, the ionic bonds are typically broken by the interaction with water, but the covalent bonds continue to hold. For

neg: Ice is unclear. Artificial nuclei are used in cloud seeding. The droplet then grows by condensation of water vapor onto the ice surfaces. So-called "diamond dust", also known as ice needles or ice crystals, forms at temperatures approaching due to air with slightly higher moisture from aloft mixing with colder, surface-based air. The METAR identifier for diamond dust within international hourly weather reports is "IC". Ablation of ice refers to both its melting and its dissolution. In fresh ambient melting describes a phase transition from solid to liquid. To melt ice means breaking the hydrogen bonds between the water molecules. The

neg: Bound water Bound water In hydrology, bound water, is an extremely thin layer of water surrounding mineral surfaces. Water molecules have a strong electrical polarity, meaning that there is a very strong positive charge on one side of the molecule and a strong negative charge on the other. This causes the water molecules to bond to each other and to other charged surfaces, such as soil minerals. Clay in particular has a high ability to bond with water molecules. The strong attraction between these surfaces causes an extremely thin water film (a few molecules thick) to form on the mineral surface. These

neg: Supercooling thermal gradient necessary to create a stable solid front is as expressed below. For more information, see the equation (3) of In order to survive extreme low temperatures in certain environments, some animals use the phenomenon of supercooling that allow them to remain unfrozen and avoid cell damage and death. There are many techniques that aid in maintaining a liquid state, such as the production of antifreeze proteins, or AFPs, which bind to ice crystals to prevent water molecules from binding and spreading the growth of ice. The winter flounder is one such fish that utilizes these proteins to survive

neg: Liquid crystal (just as water may turn into ice or steam). Liquid crystals can be divided into thermotropic, lyotropic and metallotropic phases. Thermotropic and lyotropic liquid crystals consist mostly of organic molecules, although a few minerals are also known. Thermotropic LCs exhibit a phase transition into the liquid-crystal phase as temperature is changed. Lyotropic LCs exhibit phase transitions as a function of both temperature and concentration of the liquid-crystal molecules in a solvent (typically water). Metallotropic LCs are composed of both organic and inorganic molecules; their liquid-crystal transition depends not only on temperature and concentration, but also on the inorganic-organic composition ratio.

neg: Krypton krypton oxoacid. ArKr and KrH polyatomic ions have been investigated and there is evidence for KrXe or KrXe. The reaction of with produces an unstable compound, , that contains a krypton-oxygen bond. A krypton-nitrogen bond is found in the cation [HC≡N–Kr–F], produced by the reaction of with [HC≡NH][AsF] below −50 °C. HKrCN and HKrC≡CH (krypton hydride-cyanide and hydrokryptoacetylene) were reported to be stable up to 40 K. Krypton hydride (Kr(H)) crystals can be grown at pressures above 5 GPa. They have a face-centered cubic structure where krypton octahedra are surrounded by randomly oriented hydrogen molecules. Earth has retained all of

neg: Bjerrum defect amine functional groups) in the guest molecules lead to transient hydrogen bonds and misoriented water molecules in the hydrate lattice. Bjerrum defect A Bjerrum defect is a crystallographic defect which is specific to ice, and which is partly responsible for the electrical properties of ice. It was first proposed by Niels Bjerrum in 1952 in order to explain the electrical polarization of ice in an electric field. A hydrogen bond normally has one proton, but a hydrogen bond with a Bjerrum defect will have either two protons (D defect) or no proton (L defect). The unfavorable defect strain is resolved

neg: Hydrogen bond Hydrogen bond A hydrogen bond is a partially electrostatic attraction between a hydrogen (H) atom which is bound to a more electronegative atom or group, such as nitrogen (N), oxygen (O), or fluorine (F)—the hydrogen bond donor—and another adjacent atom bearing a lone pair of electrons—the hydrogen bond acceptor. Hydrogen bonds can be intermolecular (occurring between separate molecules) or intramolecular (occurring among parts of the same molecule). Depending on the nature of the donor and acceptor atoms which constitute the bond, their geometry, and environment, the energy of a hydrogen bond can vary between 1 and 40 kcal/mol. This makes

neg: White white color from the large amount of chalk, made of limestone, which they contain, which reflects the sunlight. Snow is a mixture of air and tiny ice crystals. When white sunlight enters snow, very little of the spectrum is absorbed; almost all of the light is reflected or scattered by the air and water molecules, so the snow appears to be the color of sunlight, white. Sometimes the light bounces around inside the ice crystals before being scattered, making the snow seem to sparkle. In the case of glaciers, the ice is more tightly pressed together and contains little air.

neg: Chemical bond example, in solution, the cyanide ions, still bound together as single CN ions, move independently through the solution, as do sodium ions, as Na. In water, charged ions move apart because each of them are more strongly attracted to a number of water molecules, than to each other. The attraction between ions and water molecules in such solutions is due to a type of weak dipole-dipole type chemical bond. In melted ionic compounds, the ions continue to be attracted to each other, but not in any ordered or crystalline way. Covalent bonding is a common type of bonding, in which

neg: Hydrogen bond five the majority of orally active drug tend to have between five and ten hydrogen bonds. These interactions exist between nitrogen–hydrogen and oxygen–hydrogen centers. As with many other rules of thumb, many exceptions exist. Hydrogen bond A hydrogen bond is a partially electrostatic attraction between a hydrogen (H) atom which is bound to a more electronegative atom or group, such as nitrogen (N), oxygen (O), or fluorine (F)—the hydrogen bond donor—and another adjacent atom bearing a lone pair of electrons—the hydrogen bond acceptor. Hydrogen bonds can be intermolecular (occurring between separate molecules) or intramolecular (occurring among parts of the same

neg: Snow liquid droplets form. Clays, desert dust and biological particles can be nuclei. Artificial nuclei include particles of silver iodide and dry ice, and these are used to stimulate precipitation in cloud seeding. Once a droplet has frozen, it grows in the supersaturated environment—one where air is saturated with respect to ice when the temperature is below the freezing point. The droplet then grows by diffusion of water molecules in the air (vapor) onto the ice crystal surface where they are collected. Because water droplets are so much more numerous than the ice crystals due to their sheer abundance, the crystals

neg: Flash freezing other liquids, arises because water expands as it freezes. Once the liquid is completely frozen, the sharp tip of the drop attracts water vapor in the air, much like a sharp metal lightning rod attracts electrical charges. The water vapor collects on the tip and a tree of small ice crystals starts to grow. An opposite effect has been shown to preferentially extract water molecules from the sharp edge of potato wedges in the oven. If a microscopic droplet of water is cooled very fast, it forms what is called a glass (low-density amorphous ice) in which all the tetrahedrons

neg: Proton tunneling changes the hydrogen bond configuration; this leads to a slight alteration of the hereditary code which is the basis of mutations. Likewise, proton tunneling is also believed to be responsible for the occurrence of the dysfunction of cells (tumors and cancer) and ageing. Proton tunneling occurs in many hydrogen based molecular crystals such as ice. It is believed that the phase transition between the hexagonal (ice Ih) and orthorhombic (ice XI) phases of ice is enabled by proton tunneling. The occurrence of correlated proton tunneling in clusters of ice has also been reported recently. Proton tunneling Proton tunneling is a

neg: Scintillation (physics) photons such as gamma rays, thallium activated NaI crystals (NaI(Tl)) are often used. For a faster response (but only 5% of the output) CsF crystals can be used. In organic molecules scintillation is a product of π-orbitals. Organic materials form molecular crystals where the molecules are loosely bound by Van der Waals forces. The ground state of C is 1s 2s 2p. In valence bond theory, when carbon forms compounds, one of the 2s electrons is excited into the 2p state resulting in a configuration of 1s 2s 2p. To describe the different valencies of carbon, the four valence electron

neg: Insect winter ecology arise spontaneously from clusters of slow-moving water molecules. Alternatively, substances that facilitate the aggregation of water molecules can increase the probability that they will reach the critical size necessary for ice formation. Freeze-tolerant insects are known to produce ice nucleating proteins. The regulated production of ice nucleating proteins allows insects to control the formation of ice crystals within their bodies. The lower an insect's body temperature, the more likely it is that ice will begin to form spontaneously. Even freeze-tolerant animals cannot tolerate a sudden, total freeze; for most freeze-tolerant insects it is important that they avoid supercooling and initiate

neg: Liquid crystal windows and electrically switched between transparent and opaque to provide privacy. Many common fluids, such as soapy water, are in fact liquid crystals. Soap forms a variety of LC phases depending on its concentration in water. Bowlic columns could be used for fast switches. Liquid crystal Liquid crystals (LCs) are a state of matter which has properties between those of conventional liquids and those of solid crystals. For instance, a liquid crystal may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many different types of liquid-crystal phases, which can be distinguished by

neg: Chemical bond such bonding. Molecules which are formed primarily from non-polar covalent bonds are often immiscible in water or other polar solvents, but much more soluble in non-polar solvents such as hexane. A polar covalent bond is a covalent bond with a significant ionic character. This means that the two shared electrons are closer to one of the atoms than the other, creating an imbalance of charge. Such bonds occur between two atoms with moderately different electronegativities and give rise to dipole–dipole interactions. The electronegativity difference between the two atoms in these bonds is 0.3 to 1.7. A single bond between two

neg: Ostwald ripening to larger droplets due to greater solubility of the single monomer molecules in the larger monomer droplets. The rate of this diffusion process is linked to the solubility of the monomer in the continuous (water) phase of the emulsion. This can lead to the destabilization of emulsions (for example, by creaming and sedimentation). An everyday example of Ostwald ripening is the re-crystallization of water within ice cream which gives old ice cream a gritty, crunchy texture. Larger ice crystals grow at the expense of smaller ones within the ice cream, creating a coarser texture. Another gastronomical example is in the

neg: Poly(N-isopropylacrylamide) in interest in PNIPAs with the realization of potential applications due to its unique thermal behavior in aqueous solutions. PNIPA is one of the most studied thermosensitive hydrogels. In dilute solution, it undergoes a coil-to-globule transition. PNIPA possesses an inverse solubility upon heating. It changes hydrophilicity and hydrophobicity abruptly at its LCST. At lower temperatures PNIPA orders itself in solution in order to hydrogen bond with the already arranged water molecules. The water molecules must reorient around the nonpolar regions of PNIPA which results in a decreased entropy. At lower temperatures, such as room temperature, the negative enthalpy term (formula_1)

neg: Magnesium oxychloride anions and some unbound water molecules, yielding the general formula [] ·"n" · "n". The structure of phase 5 is believed to be similar, with generic formula []·"n" · "n"(4-"x"). The anhydrous forms of phase 3 and phase 5 have the same structure as : namely, layers of magnesium cations, each sandwiched between two layers of hydroxy or chloride anions. Phase 5 crystals form as long needles consisting of rolled-up sheets. The Raman spectrum of phase 3 has peaks at 3639 and 3657 cm, whereas phase 5 has peaks at 3608 and 3691 cm, and brucite has a peak at

neg: Ianbruceite containing loosely bound water molecules. The arsenic is tetrahedrally coordinated by four oxygen anions. Ianbruceite occurs as aggregates of tiny, radiating, lath-like crystals with a distinctive diamond-shaped outline, up to 0.2 mm across. Material from Tsumeb is blue, ranging from a very pale color to deep blue. Material from the Caldbeck Fells is white to pale pink. The crystals have a vitreous luster and a white streak. The refractive indices of ianbruceite are similar to that of ordinary window glass, with n = 1.601, n = 1.660 and n = 1.662. The refractive index varies with the wavelength (color) of

neg: Carboxymethyl cellulose modification of their shape are caused by the competition between CMC molecules and bitartrate ions for binding to the KHT crystals (Cracherau et al. 2001). In veterinary medicine, CMC is used in abdominal surgeries in large animals, particularly horses, to prevent the formation of bowel adhesions. CMC is sometimes used as an electrode binder in advanced battery applications (i.e. lithium ion batteries), especially with graphite anodes. CMC's water solubility allows for less toxic and costly processing than with non-water soluble binders, like the traditional polyvinylidene fluoride (PVDF), which requires toxic n-methylpyrrolidone (NMP) for processing. CMC is often used in conjunction

neg: Water of crystallization Water of crystallization In chemistry, water of crystallization or water of hydration are water molecules that are present inside crystals. Water is often incorporated in the formation of crystals from aqueous solutions. In some contexts, water of crystallization is the total mass of water in a substance at a given temperature and is mostly present in a definite (stoichiometric) ratio. Classically, "water of crystallization" refers to water that is found in the crystalline framework of a metal complex or a salt, which is not directly bonded to the metal cation. Upon crystallization from water or moist solvents, many compounds incorporate

neg: Lipid bilayer two “leaflets” that are each a single molecular layer. The center of this bilayer contains almost no water and excludes molecules like sugars or salts that dissolve in water. The assembly process is driven by interactions between hydrophobic molecules (also called the hydrophobic effect). An increase in interactions between hydrophobic molecules (causing clustering of hydrophobic regions) allows water molecules to bond more freely with each other, increasing the entropy of the system. This complex process includes non-covalent interactions such as van der Waals forces, electrostatic and hydrogen bonds. The lipid bilayer is very thin compared to its lateral dimensions. If

neg: Frazil ice Frazil ice Frazil ice is a collection of loose, randomly oriented, plate or discoid ice crystals formed in supercooled turbulent water . Frazil ice formation is common during the winter in rivers and lakes located in northern latitudes, and usually forms in open-water reaches of rivers where and when the heat exchange between the air and the water is such that the water temperature can drop below its freezing point (typically not lower than -0.1 °C in rivers). As a rule of thumb, such conditions may happen on cold and clear nights, when the air temperature is lower than .

neg: Chemistry aqueous solution (that is, in water). Less familiar phases include plasmas, Bose–Einstein condensates and fermionic condensates and the paramagnetic and ferromagnetic phases of magnetic materials. While most familiar phases deal with three-dimensional systems, it is also possible to define analogs in two-dimensional systems, which has received attention for its relevance to systems in biology. Atoms sticking together in molecules or crystals are said to be bonded with one another. A chemical bond may be visualized as the multipole balance between the positive charges in the nuclei and the negative charges oscillating about them. More than simple attraction and repulsion, the

neg: Water-in-water emulsion Permeability on the Dynamical Behavior of Water-in-Water Emulsions. Journal of Physical Chemistry B 2006, 110, (7), 3250–3256. 1. Salt bridging and example of salt bridges http://www.cryst.bbk.ac.uk/PPS2/projects/day/TDayDiss/SaltBridges.html 2. Tutorial on liquid crystals http://outreach.lci.kent.edu/ 3. Introduction to polymer dispersed liquid crystals (PDLC) 4. Droplet configuration of PDLC’s http://plc.cwru.edu/tutorial/enhanced/files/pdlc/droplet/droplet.htm Water-in-water emulsion Water-in-water (W/W) emulsion is a system that consists of droplets of water-solvated molecules in another continuous aqueous solution; both the droplet and continuous phases contain different molecules that are entirely water-soluble. As such, when two entirely aqueous solutions containing different water-soluble molecules are mixed, water droplets containing predominantly one component are dispersed

neg: Covalent radius of fluorine of the electron density distribution were then drawn, which were used to evaluate the bond length of fluorine to other molecules. The authors found that the length of X-F bonds decrease as the product of the charges on A and F increases. Furthermore, the X-F bond length decreases with a decreasing coordination number n. The number of fluorine atoms that are packed around the central atom is an important factor for calculating the bond length. Also, the smaller the bond angle (<FXF) between F and the central atom, the longer the bond length of fluorine. Finally, the most accurate value

neg: Neon compounds crystals of ammonium iron formate (NHFe(HCOO)) and ammonium nickel formate (NHNi(HCOO)) at 1.5 GPa to yield Ne•NHFe(HCOO) and Ne•NHNi(HCOO). The neon atoms become trapped in a cage of five metal triformate units. The windows in the cages are blocked by ammonium ions. Argon does not undergo this, probably as its atoms are too big. Ionic molecules can include neon, such as the clusters where "m" goes from 1 to 7 and "n" from 1 to over 20. HeNe (helium neide) has a relatively strong covalent bond. The charge is distributed across both atoms. When metals are evaporated into a thin

neg: Thalappil Pradeep H makes hydronium ion in liquid water, it results in dihydrogen cation on ice. He showed that molecular transport of even slightly different molecules is largely different within ice. To discover and understand such processes, especially at the very top of ice, he built the very first ultra low energy (1-10 eV) ion scattering spectrometer, a new tool in extremely surface sensitive spectroscopy, working at cryogenic temperatures as in space. In this experiment, mass and energy selected ions undergo collisions at ultra-thin molecular surfaces prepared on single crystals and the product ions are studied by a mass spectrometer. The surfaces

neg: Metal ions in aqueous solution solutions it merges into the water structure in which there is an irregular network of hydrogen bonds between water molecules. With tripositive ions the high charge on the cation polarizes the water molecules in the first solvation shell to such an extent that they form strong enough hydrogen bonds with molecules in the second shell to form a more stable entity. The strength of the metal-oxygen bond can be estimated in various ways. The hydration enthalpy, though based indirectly on experimental measurements, is the most reliable measure. The scale of values is based on an arbitrarily chosen zero, but this

neg: A Guide to the Scientific Knowledge of Things Familiar America IV: the American voice, 1850–1877". Brewer said that he consulted "the most approved modern authors" and submitted additions to "the revision of gentlemen of acknowledged reputation for scientific attainments". Nevertheless, religious rather than scientific answers to certain questions are prevalent in the book, particularly answers inferring divine design. For example, although modern theories of ice formation show that most of its unusual properties result from the hydrogen bond between neighbouring water molecules, Brewer suggested that the reason ice is lighter than water, expanding as it freezes, is because it has been "wisely ordained by God that water shall be

neg: Frazil ice the crystals grow in number and size, the frazil ice will begin to adhere to objects in the water, especially if the objects themselves are at a temperature below water’s freezing point. The accumulation of frazil ice often causes flooding or damage to objects such as trash racks. Since frazil ice is found below the surface of water, it is difficult to detect its formation. Usually what happens is the frazil ice accumulates on the upstream side of objects and sticks to them. The frazil ice accumulates as more gets deposited. The growth will extend upstream and increase in width

neg: Hydrate molecule of water may be eliminated, for example by the action of sulfuric acid. Another example is chloral hydrate, CCl–CH(OH), which can be formed by reaction of water with chloral, CCl–CH=O. Many organic molecules, as well as inorganic molecules, form crystals that incorporate water into the crystalline structure without chemical alteration of the organic molecule (water of crystallization). The sugar trehalose, for example, exists in both an anhydrous form (melting point 203 °C) and as a dihydrate (melting point 97 °C). Protein crystals commonly have as much as 50% water content. Molecules are also labeled as hydrates for historical reasons

neg: ADP-ribosylation ADP-ribosylhydrolases, which cleave the N-glycosidic bond between arginine and ribose to release ADP-ribose and unmodified protein; NAD+ is not restored by the reverse reaction. Poly-(ADP-ribose) polymerases (PARPs) are found mostly in eukaryotes and catalyze the transfer of multiple ADP-ribose molecules to target proteins. As with mono-ADP ribosylation, the source of ADP-ribose is NAD. PARPs use a catalytic triad of His-Tyr-Glu to facilitate binding of NAD and positioning of the end of the existing poly-ADP ribose chain on the target protein; the Glu facilitates catalysis and formation of a (1->2) O-glycosidic linkage between two ribose molecules. There are several other enzymes

neg: Ammonium fluoride Ammonium fluoride Ammonium fluoride is the inorganic compound with the formula NHF. It crystallizes as small colourless prisms, having a sharp saline taste, and is exceedingly soluble in water. Ammonium fluoride adopts the wurtzite crystal structure, in which both the ammonium cations and the fluoride anions are stacked in ABABAB... layers, each being tetrahedrally surrounded by four of the other. There are N−H···F hydrogen bonds between the anions and cations. This structure is very similar to ice, and ammonium fluoride is the only substance which can form mixed crystals with water. On passing hydrogen fluoride gas (in excess) through the

neg: Triple bond Triple bond A triple bond in chemistry is a chemical bond between two atoms involving six bonding electrons instead of the usual two in a covalent single bond. The most common triple bond, that between two carbon atoms, can be found in alkynes. Other functional groups containing a triple bond are cyanides and isocyanides. Some diatomic molecules, such as dinitrogen and carbon monoxide, are also triple bonded. In skeletal formula the triple bond is drawn as three parallel lines (≡) between the two connected atoms. Triple bonds are stronger than the equivalent single bonds or double bonds, with a bond

neg: Cryostasis (clathrate hydrates) of the solutions, the ice crystals grow between the cells, extracting water from them. As the ice crystals grow, the volume of the cells shrinks, and the cells are crushed between the ice crystals. Additionally, as the cells shrink, the solutes inside the cells are concentrated in the remaining water, increasing the intracellular ionic strength and interfering with the organization of the proteins and other organized intercellular structures. Eventually, the solute concentration inside the cells reaches the eutectic and freezes. The final state of frozen tissues is pure ice in the former extracellular spaces, and inside the cell membranes a

neg: Properties of water amalgamated crystals, such as ice cubes, or loosely accumulated granular crystals, like snow. Aside from common hexagonal crystalline ice, other crystalline and amorphous phases of ice are known. The gaseous phase of water is known as water vapor (or steam). Visible steam and clouds are formed from minute droplets of water suspended in the air. Water also forms a supercritical fluid. The critical temperature is 647 K and the critical pressure is 22.064 MPa. In nature this only rarely occurs in extremely hostile conditions. A likely example of naturally occurring supercritical water is in the hottest parts of deep water

neg: Bond order Bond order Bond order is the number of chemical bonds between a pair of atoms. For example, in diatomic nitrogen N≡N the bond order is 3, in acetylene the bond order between the two carbon atoms is also 3, and the bond order is 1. Bond order gives an indication of the stability of a bond. Isoelectronic species have same bond number. In molecules that have resonance or nonclassical bonding, bond order may not be an integer. In benzene, the delocalized molecular orbitals contain 6 pi electrons over six carbons essentially yielding half a pi bond together with the sigma

neg: Isopropyl cyanide even before the process of star formation or before planets such as the Earth were formed. The importance of the cyanides found in comets remains in their C-N bond. This bond has been proved to participate in the abiotic amino acid synthesis. The two cyanide molecules – isopropyl cyanide and normal-propyl cyanide – are the largest molecules yet detected in any star-forming region. Some more specific properties are: Chemically speaking, the simple inorganic cyanides behave as chlorides in many ways. Organic nitriles act as solvents and are reacted further for various applications such as: Working as an extraction solvent for

neg: Exciton of the unit cell. Molecular excitons may even be entirely located on the same molecule, as in fullerenes. This "Frenkel exciton", named after Yakov Frenkel, has a typical binding energy on the order of 0.1 to 1 eV. Frenkel excitons are typically found in alkali halide crystals and in organic molecular crystals composed of aromatic molecules, such as anthracene and tetracene. In semiconductors, the dielectric constant is generally large. Consequently, electric field screening tends to reduce the Coulomb interaction between electrons and holes. The result is a "Wannier exciton", which has a radius larger than the lattice spacing. Small effective

neg: Neon compounds in this molecule. Beryllium sulfite molecules BeOS, can also coordinate neon onto the beryllium atom. The dissociation energy for neon is 0.9 kcal/mol. When neon is added to the cyclic molecule, the ∠O-Be-O decreases and the O-Be bond lengths increase. High pressure Van der Waals solids include (N)Ne. Neon hydrate or neon clathrate, a clathrate, can form in ice II at 480 MPa pressure between 70 K and 260 K. Other neon hydrates are also predicted resembling hydrogen clathrate, and those clathrates of helium. These include the C, ice I and ice I forms. Neon atoms can be trapped inside

neg: Rain most often in clouds above freezing, and is also known as the warm rain process. In clouds below freezing, when ice crystals gain enough mass they begin to fall. This generally requires more mass than coalescence when occurring between the crystal and neighboring water droplets. This process is temperature dependent, as supercooled water droplets only exist in a cloud that is below freezing. In addition, because of the great temperature difference between cloud and ground level, these ice crystals may melt as they fall and become rain. Raindrops have sizes ranging from mean diameter, above which they tend to break

neg: Brinicle as a brinicle. The formation of ice from salt water produces marked changes in the composition of the nearby unfrozen water. When water freezes, most impurities are excluded from the water crystals; even ice from seawater is relatively fresh compared with the seawater from which it is formed. As a result of forcing the impurities out, such as salt and other ions, sea ice is very porous and spongelike, quite different from the solid ice produced when fresh water freezes. As the seawater freezes and salt is forced out of the pure ice crystal lattice, the surrounding water becomes more

neg: Ice Ih as it cools to absolute zero. As a result, the crystal structure contains some residual entropy inherent to the lattice and determined by the number of possible configurations of hydrogen positions that can be formed while still maintaining the requirement for each oxygen atom to have only two hydrogens in closest proximity, and each H-bond joining two oxygen atoms having only one hydrogen atom. This residual entropy "S" is equal to 3.5 J mol K. There are various ways of approximating this number from first principles. Suppose there are a given number "N" of water molecules. The oxygen atoms form

neg: Organic superconductor phase with the molecules ordering in a fishbone structure and the β- and especially κ-phase which order in a checkerboard structure with molecules being dimerized in the κ-phase. This dimerization makes the κ-phases special as they are not quarter- but half-filled systems, driving them into superconductivity at higher temperatures compared to the other phases. The amount of possible anions separating two sheets of ET-molecules is nearly infinite. There are simple anions such as I, polymeric ones such as the very famous Cu[N(CN)]Br and anions containing solvents for example Ag(CF)·112DCBE. The electronic properties of the ET-based crystals are determined by its

neg: Subsun Subsun A subsun or "sub-sun" is a glowing spot that can be seen within clouds or haze when observed from above. The subsun appears directly below the sun, and is caused by its light reflecting off of numerous tiny ice crystals suspended in the atmosphere. As such the effect belongs to the family of halos. The region of ice crystals acts as a large mirror, creating a virtual image of the sun which appears below the horizon, analogous to the sun's reflection in a body of water. The ice crystals responsible for a subsun are typically in the shape of

neg: Exciton may transfer ("hop") from one molecule to another. The process is strongly dependent on intermolecular distance between the species in solution, and so the process has found application in sensing and "molecular rulers". The hallmark of molecular excitons in organic molecular crystals are doublets and/or triplets of exciton absorption bands strongly polarized along crystallographic axes. In these crystals an elementary cell includes several molecules sitting in symmetrically identical positions, which results in the level degeneracy that is lifted by intermolecular interaction. As a result, absorption bands are polarized along the symmetry axes of the crystal. Such multiplets were discovered by

neg: Water-in-water emulsion clumping together. 3. In addition, it is also proposed that when two liquid crystal droplets merge (coalescence), the orientation of the liquid crystal molecules in the two merging droplets must change to “adapt” to each other, and thus incur an energy penalty which prevent the occurrence of coalescence. This w/w emulsion also represents a new class of polymer dispersed liquid crystals(PDLC). Traditionally known PDLC consists of oil-in-water emulsion where the oily droplet is a thermotropic liquid crystal such as 4-pentyl-4'-cyanobiphenyl (5CB), and the water phase contains certain polymers. In comparison, this water-in-water emulsion consists of Polymer-Dispersed Lyotropic Liquid Crystals, where

neg: Mineralized tissues hundred nanometres. The second are the elementary components of mineralized tissues at a scale of tens of nanometres. The components are the mineral crystals of hydroxyapatite, cylindrical collagen molecules, organic molecules such as lipids and proteins, and finally water. The hierarchical structure common to all mineralized tissues is the key to their mechanical performance. The mineral is the inorganic component of mineralized tissues. This constituent is what makes the tissues harder and stiffer. Hydroxyapatite, calcium carbonate, silica, calcium oxalate, whitlockite, and monosodium urate are examples of minerals found in biological tissues. In mollusc shells, these minerals are carried to the

neg: Hydrogen bond water under such conditions. It is a crucial part of the uniqueness of water. Because water may form hydrogen bonds with solute proton donors and acceptors, it may competitively inhibit the formation of solute intermolecular or intramolecular hydrogen bonds. Consequently, hydrogen bonds between or within solute molecules dissolved in water are almost always unfavorable relative to hydrogen bonds between water and the donors and acceptors for hydrogen bonds on those solutes. Hydrogen bonds between water molecules have an average lifetime of 10 seconds, or 10 picoseconds. A single hydrogen atom can participate in two hydrogen bonds, rather than one. This

neg: Spin ice as water ice. Be that as it may, depending on the specific spin ice material, it is generally much easier to create large single crystals of spin ice materials than water ice crystals. Additionally, the ease to induce interaction of the magnetic moments with an external magnetic field in a spin ice system makes the spin ices more suitable than water ice for exploring how the residual entropy can be affected by external influences. While Philip Anderson had already noted in 1956 the connection between the problem of the frustrated Ising antiferromagnet on a (pyrochlore) lattice of corner-shared tetrahedra and

neg: Molecular electronic transition Electrons occupying a HOMO of a sigma bond can get excited to the LUMO of that bond. This process is denoted as a σ → σ transition. Likewise promotion of an electron from a π-bonding orbital to an antibonding π orbital is denoted as a π → π transition. Auxochromes with free electron pairs denoted as n have their own transitions, as do aromatic pi bond transitions. Sections of molecules which can undergo such detectable electron transitions can be referred to as chromophores since such transitions absorb electromagnetic radiation (light), which may be hypothetically perceived as color somewhere in the

neg: Atmosphere of Mars from sand storms and dust devils. The ice can be found in trenches or in the permafrost. The electrical discharge ionizes gaseous CO and water molecules and their byproducts recombine to produce methane. The results obtained show that pulsed electrical discharges over ice samples in a Martian atmosphere produce about 1.41×10 molecules of methane per joule of applied energy. Living microorganisms, such as methanogens, are another possible source, but no evidence for the presence of such organisms has been found on Mars. In Earth's oceans, biological methane production tends to be accompanied by ethane, whereas volcanic methane is accompanied by

neg: Snowmaking through an intricate series of valves and pipes to any trails that require snowmaking. Many resorts also add a nucleating agent to ensure that as much water as possible freezes and turns into snow. These products are organic or inorganic materials that facilitate the water molecules to form the proper shape to freeze into ice crystals. The products are non-toxic and biodegradable. The next step in the snowmaking process is to add air using an air plant. This plant is often a building which contains electric or diesel industrial air compressors the size of a van or truck. However, in

neg: Hypervalent molecule octet rule). Several specific classes of hypervalent molecules exist: N-X-L nomenclature, introduced collaboratively by the research groups of Martin, Arduengo, and Kochi in 1980, is often used to classify hypervalent compounds of main group elements, where: Examples of N-X-L nomenclature include: The debate over the nature and classification of hypervalent molecules goes back to Gilbert N. Lewis and Irving Langmuir and the debate over the nature of the chemical bond in the 1920s. Lewis maintained the importance of the two-center two-electron (2c-2e) bond in describing hypervalence, thus using expanded octets to account for such molecules. Using the language of orbital

neg: Super-dense water formation. It is also speculated that super-dense water is located in Towradgi, New South Wales. Super-dense water Super-dense water is water that has been contained in an environment with both molecular uniformity and extreme depth, which causes the molecules of water to be packed tightly together and thus gain a tougher solidity and higher density than regular ice. Super dense water is found on planets, such as the moons Tethys, Ganymede, Callisto, and Europa in the Solar System, which are covered entirely in water and have little to no landmass. Speculation exists that a planet located at around 30 light-years

neg: Carbon–carbon bond of life, so carbon compounds have their own field of study: organic chemistry. Branching is also common in C−C skeletons. Different carbon atoms can be described by the number of carbon neighbors they each have: In "structurally complex organic molecules", it is the three-dimensional orientation of the carbon–carbon bonds at quaternary loci which dictates the shape of the molecule. Further, quaternary loci are found in many biologically active small molecules, such as cortisone and morphine. Carbon–carbon bond-forming reactions are organic reactions in which a new carbon–carbon bond is formed. They are important in the production of many man-made chemicals such

neg: Triple bond formation of one sigma bond and two pi bonds. In the bent bond model, the triple bond can also formed by the overlapping of three sp lobes without the need to invoke a pi-bond. Triple bond A triple bond in chemistry is a chemical bond between two atoms involving six bonding electrons instead of the usual two in a covalent single bond. The most common triple bond, that between two carbon atoms, can be found in alkynes. Other functional groups containing a triple bond are cyanides and isocyanides. Some diatomic molecules, such as dinitrogen and carbon monoxide, are also triple

neg: Slurry ice is created through a process of forming spherical ice crystals within a liquid. The slurry ice generator is a scraped-surface vertical shell and tube heat exchanger. It consists of concentric tubes with refrigerant flowing between them and the water/freezing point depressant solution in the inner tube. The inner surface of the inner tube is wiped using a wiping mechanism which in the original Sunwell design consists of a central shaft, spring-loaded plastic blades, bearings and seals. The small ice crystals formed in the solution near the tube surface are wiped away from the surface and mixed with unfrozen water, forming

neg: Uranus pressure and temperature deep within Uranus may break up the methane molecules, with the carbon atoms condensing into crystals of diamond that rain down through the mantle like hailstones. Very-high-pressure experiments at the Lawrence Livermore National Laboratory suggest that the base of the mantle may comprise an ocean of liquid diamond, with floating solid 'diamond-bergs'. The bulk compositions of Uranus and Neptune are different from those of Jupiter and Saturn, with ice dominating over gases, hence justifying their separate classification as ice giants. There may be a layer of ionic water where the water molecules break down into a soup

neg: Direct bonding the wafers start to bond as soon as they get in atomic contact as shown in infrared photograph of a bond wave. The wafers are covered with water molecules so the bonding happens between chemisorbed water molecules on the opposing wafer surfaces. In consequence a significant fraction of Si-OH (silanol) groups start to polymerize at room temperature forming Si-O-Si and water and a sufficient bonding strength for handling the wafer stack is assured. The formed water molecules will migrate or diffuse along the interface during annealing. After the pre-bonding in air, in a special gaseous atmosphere or vacuum, the wafers

neg: Metal ions in aqueous solution known. In aqueous solution the water molecules directly attached to the metal ion are said to belong to the first coordination sphere, also known as the first, or primary, solvation shell. The bond between a water molecule and the metal ion is a dative covalent bond, with the oxygen atom donating both electrons to the bond. Each coordinated water molecule may be attached by hydrogen bonds to other water molecules. The latter are said to reside in the second coordination sphere. The second coordination sphere is not a well defined entity for ions with charge 1 or 2. In dilute

neg: Properties of water versa for the positive dipole ends. In general, ionic and polar substances such as acids, alcohols, and salts are relatively soluble in water, and non-polar substances such as fats and oils are not. Non-polar molecules stay together in water because it is energetically more favorable for the water molecules to hydrogen bond to each other than to engage in van der Waals interactions with non-polar molecules. An example of an ionic solute is table salt; the sodium chloride, NaCl, separates into cations and anions, each being surrounded by water molecules. The ions are then easily transported away from their crystalline

neg: Phosphenium angle of 120°. The tighter N-P-N angle observed in the crystal structure can be interpreted as the result of repulsion between the phosphorus lone pair with the bulky "i"-PrN ligands, as the P(NH) and PH molecules have bond angles closer to 110° and 90°, respectively. Phosphenium is isoelectronic with singlet (Fisher) carbenes and are therefore predicted to behave as both a Lewis acid and a Lewis base. The Lewis acidity of phosphenium is evident from the reaction of model phosphenium ions, such as [P(NMe)] and [P(NMe)Cl] with a Lewis base such as P(NMe). Such a reaction results in the formation

neg: Raman spectroscopy labels of vibrational modes. In the solid state, polarized Raman spectroscopy can be useful in the study of oriented samples such as single crystals. The polarizability of a vibrational mode is not equal along and across the bond. Therefore the intensity of the Raman scattering will be different when the lasers polarization is along and orthogonal to a particular bonds axis. This effect can provide information on the orientation of molecules with a single crystal or material. The spectral information arising from this analysis is often used to understand macromolecular orientation in crystal lattices, liquid crystals or polymer samples. The

neg: Ice-type model Ice-type model In statistical mechanics, the ice-type models or six-vertex models are a family of vertex models for crystal lattices with hydrogen bonds. The first such model was introduced by Linus Pauling in 1935 to account for the residual entropy of water ice. Variants have been proposed as models of certain ferroelectric and antiferroelectric crystals. In 1967, Elliott H. Lieb found the exact solution to a two-dimensional ice model known as "square ice". The exact solution in three dimensions is only known for a special "frozen" state. An ice-type model is a lattice model defined on a lattice of coordination

neg: Super-dense water Super-dense water Super-dense water is water that has been contained in an environment with both molecular uniformity and extreme depth, which causes the molecules of water to be packed tightly together and thus gain a tougher solidity and higher density than regular ice. Super dense water is found on planets, such as the moons Tethys, Ganymede, Callisto, and Europa in the Solar System, which are covered entirely in water and have little to no landmass. Speculation exists that a planet located at around 30 light-years away from Earth may contain super-dense water. See ocean planet for more information on its

neg: R. Tom Baker homogeneous catalysts to facilitate aerobic oxidation of lignocellulose to obtain small monomeric organic molecules which can produce more valuable chemicals and renewable biofuels. This research includes investigating reactivity and oxidation selectivity of different metal catalysts towards a variety of lignin models, a study of C-O bond and C-C bond cleavage pathways towards simple and complex lignin models, and the function of base in the aerobic oxidation process. Baker’s recent research also includes the development of tandem catalytic system to convert ethanol to n-butanol with high selectivity. "N"-butanol, owing to its high energy density and immiscibility with water, is known as

neg: Supersaturation relevant to atmospheric studies. Since the 1940s, the presence of supersaturation in the atmosphere has been known. When water is supersaturated in the troposphere, the formation of ice lattices is frequently observed. In a state of saturation, the water particles will not form ice under tropospheric conditions. It is not enough for molecules of water to form an ice lattice at saturation pressures; they require a surface to condense on to or conglomerations of liquid water molecules of water to freeze. For these reasons, relative humidities over ice in the atmosphere can be found above 100%, meaning supersaturation has occurred.

neg: Superhard material result is darker and larger (500 μm) crystals with better shapes and a higher yield. Cubic boron nitride adopts a sphalerite crystal structure, which can be constructed by replacing every two carbon atoms in diamond with one boron atom and one nitrogen atom. The short B-N (1.57 Å) bond is close to the diamond C-C bond length (1.54 Å), that results in strong covalent bonding between atoms in the same fashion as in diamond. The slight decrease in covalency for B-N bonds compared to C-C bonds reduces the hardness from ~100 GPa for diamond down to 48 GPa in c-BN.

neg: Cryonics popular belief, water that freezes during cryopreservation is usually water outside cells, not water inside cells. Cells don't burst during freezing, but instead become dehydrated and compressed between ice crystals that surround them. Intracellular ice formation only occurs if the rate of freezing is faster than the rate of osmotic loss of water to the extracellular space. Without cryoprotectants, cell shrinkage and high salt concentrations during freezing usually prevent frozen cells from functioning again after thawing. In tissues and organs, ice crystals can also disrupt connections between cells that are necessary for organs to function. The difficulties of recovering large

neg: Microstructure example, between a metal atom that has released an electron and a non-metal atom that has captured the free electron. After bonding, both atoms become charged. These bonds are found in minerals, ceramics, biological materials, and certain polymers (ionomers). Weak polar bonds are electrostatic and correspond to simple attractions between dipoles in compounds or molecules with inhomogeneous or polarizable charges. They act over long distances but with less intensity than strong bonds. Among them, for example, are van der Waals bonds between molecules and hydrogen bonds between water molecules in liquid water and ice. These bonds are found in all

neg: Fish processing that keeps the fish moist and in an easily stored form suitable for transport. It has become widely used since the development of mechanical refrigeration, which makes ice easy and cheap to produce. Ice is produced in various shapes; crushed ice and Flake Ice, plates, tubes and blocks are commonly used to cool fish. Particularly effective is slurry ice, made from micro crystals of ice formed and suspended within a solution of water and a freezing point depressant, such as common salt. A more recent development is pumpable ice technology. Pumpable ice flows like water, and because it is homogeneous,

neg: Sea ice up further into random-shaped small crystals which form a suspension of increasing density in the surface water, an ice type called frazil or grease ice. In quiet conditions the frazil crystals soon freeze together to form a continuous thin sheet of young ice; in its early stages, when it is still transparent — that is the ice called "nilas". Once nilas has formed, a quite different growth process occurs, in which water freezes on to the bottom of the existing ice sheet, a process called "congelation" growth. This growth process yields first-year ice. In rough water, fresh sea ice is

neg: Chemical bonding of H2O Chemical bonding of H2O Water () is a simple triatomic bent molecule with C molecular symmetry and bond angle of 104.5° between the central oxygen atom and the hydrogen atoms. Despite being one of the simplest triatomic molecules, its chemical bonding scheme is nonetheless complex as many of its bonding properties such as bond angle, ionization energy, and electronic state energy cannot be explained by one unified bonding model. Instead, several traditional and advanced bonding models such as simple Lewis and VESPR structure, valence bond theory, molecular orbital theory, isovalent hybridization, and Bent’s rule are discussed below to provide a

neg: Walsh diagram remains a topic of debate. A typical prediction result for water is a bond angle of 90°, which is not even close to the experimental derived value of 104°. At best the method is able to differentiate between a bent and linear molecule. This same concept can be applied to other species including non-hydride AB and BAC molecules, HAB and HAAH molecules, tetraatomic hydride molecules (AH), tetraatomic nonhydride molecules (AB), HAB molecules, acetaldehyde, pentaatomic molecules (CH3I), hexaatomic molecules (ethylene), and benzene. Walsh diagrams in conjunction with molecular orbital theory can also be used as a tool to predict reactivity. By

neg: Spin ice fact that the hexagonal crystalline structure of common water ice contains oxygen atoms with four neighboring hydrogen atoms. In ice, for each oxygen atom, two of the neighboring hydrogen atoms are near (forming the traditional HO molecule), and two are further away (being the hydrogen atoms of two neighboring water molecules). Pauling noted that the number of configurations conforming to this "two-near, two-far" ice rule grows exponentially with the system size, and, therefore, that the zero-temperature entropy of ice was expected to be extensive. Pauling's findings were confirmed by specific heat measurements, though pure crystals of water ice are particularly

neg: Frazil ice supercooled water throughout its entire depth. The supercooled water will already be encouraging the formation of small ice crystals (frazil ice) and the crystals get taken to the bottom of the water body. Ice generally floats, but due to frazil ice's small size relative to current speeds, it has an ineffective buoyancy and can be carried to the bottom very easily. Through a process called secondary nucleation, the crystals quickly increase in number, and because of its supercooled surrounding, the crystals will continue to grow. Sometimes, the concentration is estimated to reach one million ice crystals per cubic meter. As

neg: Chemistry energies and distributions characterize the availability of an electron to bond to another atom. A chemical bond can be a covalent bond, an ionic bond, a hydrogen bond or just because of Van der Waals force. Each of these kinds of bonds is ascribed to some potential. These potentials create the interactions which hold atoms together in molecules or crystals. In many simple compounds, valence bond theory, the Valence Shell Electron Pair Repulsion model (VSEPR), and the concept of oxidation number can be used to explain molecular structure and composition. An ionic bond is formed when a metal loses one

neg: Liquid-crystal display Many of the comparisons are with CRT displays. Several different families of liquid crystals are used in liquid crystals. The molecules used have to be anisotropic, and to exhibit mutual attraction. Polarizable rod-shaped molecules (biphenyls, terphenyls, etc.) are common. A common form is a pair of aromatic benzene rings, with a nonpolar moiety (pentyl, heptyl, octyl, or alkyl oxy group) on one end and polar (nitrile, halogen) on the other. Sometimes the benzene rings are separated with an acetylene group, ethylene, CH=N, CH=NO, N=N, N=NO, or ester group. In practice, eutectic mixtures of several chemicals are used, to achieve wider