query: who discovered that the number of protons for each element 's atoms is unique

pos: Atomic number of the extra protons presumed present in all heavy nuclei. A helium nucleus was presumed to be composed of four protons plus two "nuclear electrons" (electrons bound inside the nucleus) to cancel two of the charges. At the other end of the periodic table, a nucleus of gold with a mass 197 times that of hydrogen, was thought to contain 118 nuclear electrons in the nucleus to give it a residual charge of + 79, consistent with its atomic number. All consideration of nuclear electrons ended with James Chadwick's discovery of the neutron in 1932. An atom of gold now

pos: Whole number rule the other elements were a combination of different numbers of hydrogen atoms. In 1920, Francis W. Aston demonstrated through the use of a mass spectrometer that apparent deviations from Prout's hypothesis are predominantly due to the existence of isotopes. These deviations are secondarily due to binding energy, as mass defect. During the 1920s, it was thought that the atomic nucleus was made of protons and electrons, which would account for the disparity between the atomic number of an atom and its atomic mass. In 1932, James Chadwick discovered an uncharged particle of approximately the mass as the proton, which he

neg: Chemistry: A Volatile History chemist Henry Moseley speculated that the answer to the number of protons lay in the nucleus. By firing a radioactive source at copper, he was able to knock electrons from their atoms, releasing a burst of energy in the form of an x-ray. When measured, the x-rays always had the same energy, unique to copper. He discovered each element released x-rays of different energies. Moseley's brilliance was to realise the x-ray energy is related to the number of protons inside the atom: the atomic number. Because this is the number of protons, the atomic number must be a whole number

neg: Proton that all atoms with 17 protons are chlorine atoms. The chemical properties of each atom are determined by the number of (negatively charged) electrons, which for neutral atoms is equal to the number of (positive) protons so that the total charge is zero. For example, a neutral chlorine atom has 17 protons and 17 electrons, whereas a Cl anion has 17 protons and 18 electrons for a total charge of −1. All atoms of a given element are not necessarily identical, however, as the number of neutrons may vary to form different isotopes, and energy levels may differ forming different

neg: Chemical element same atomic number, or number of protons. Nuclear scientists, however, define a pure element as one that consists of only one stable isotope. For example, a copper wire is 99.99% chemically pure if 99.99% of its atoms are copper, with 29 protons each. However it is not isotopically pure since ordinary copper consists of two stable isotopes, 69% Cu and 31% Cu, with different numbers of neutrons. However, a pure gold ingot would be both chemically and isotopically pure, since ordinary gold consists only of one isotope, Au. Atoms of chemically pure elements may bond to each other chemically in

neg: Atom of nucleons. This is much smaller than the radius of the atom, which is on the order of 10 fm. The nucleons are bound together by a short-ranged attractive potential called the residual strong force. At distances smaller than 2.5 fm this force is much more powerful than the electrostatic force that causes positively charged protons to repel each other. Atoms of the same element have the same number of protons, called the atomic number. Within a single element, the number of neutrons may vary, determining the isotope of that element. The total number of protons and neutrons determine the

neg: Chemical element hydrogen and deuterium). Thus, all carbon isotopes have nearly identical chemical properties because they all have six protons and six electrons, even though carbon atoms may, for example, have 6 or 8 neutrons. That is why the atomic number, rather than mass number or atomic weight, is considered the identifying characteristic of a chemical element. The symbol for atomic number is "Z". Isotopes are atoms of the same element (that is, with the same number of protons in their atomic nucleus), but having "different" numbers of neutrons. Thus, for example, there are three main isotopes of carbon. All carbon atoms

neg: Proton number of protons, each element has its own unique atomic number. The word "proton" is Greek for "first", and this name was given to the hydrogen nucleus by Ernest Rutherford in 1920. In previous years, Rutherford had discovered that the hydrogen nucleus (known to be the lightest nucleus) could be extracted from the nuclei of nitrogen by atomic collisions. Protons were therefore a candidate to be a fundamental particle, and hence a building block of nitrogen and all other heavier atomic nuclei. In the modern Standard Model of particle physics, protons are hadrons, and like neutrons, the other nucleon (particles

neg: Chemical element Chemical element A chemical element is a species of atoms having the same number of protons in their atomic nuclei (that is, the same atomic number, or "Z"). For example, the atomic number of oxygen is 8, so the element oxygen consists of all atoms which have exactly 8 protons. 118 elements have been identified, of which the first 94 occur naturally on Earth with the remaining 24 being synthetic elements. There are 80 elements that have at least one stable isotope and 38 that have exclusively radionuclides, which decay over time into other elements. Iron is the most abundant

neg: Chemical element by symbol, as well as ionization energies of the elements. The nuclides of stable and radioactive elements are also available as a list of nuclides, sorted by length of half-life for those that are unstable. One of the most convenient, and certainly the most traditional presentation of the elements, is in the form of the periodic table, which groups together elements with similar chemical properties (and usually also similar electronic structures). The atomic number of an element is equal to the number of protons in each atom, and defines the element. For example, all carbon atoms contain 6 protons in

neg: Nuclear binding energy Only under conditions of extreme pressure and temperature (for example, within the core of a star), can such a process take place. There are around 94 naturally occurring elements on earth. The atoms of each element have a nucleus containing a specific number of protons (always the same number for a given element), and some number of neutrons, which is often roughly a similar number. Two atoms of the same element having different numbers of neutrons are known as isotopes of the element. Different isotopes may have different properties - for example one might be stable and another might be

neg: Chemistry number, and preferred types of bonds to form (e.g., metallic, ionic, covalent). A chemical element is a pure substance which is composed of a single type of atom, characterized by its particular number of protons in the nuclei of its atoms, known as the atomic number and represented by the symbol "Z". The mass number is the sum of the number of protons and neutrons in a nucleus. Although all the nuclei of all atoms belonging to one element will have the same atomic number, they may not necessarily have the same mass number; atoms of an element which have

neg: Chemical element February 2010. The heaviest element that is believed to have been synthesized to date is element 118, oganesson, on 9 October 2006, by the Flerov Laboratory of Nuclear Reactions in Dubna, Russia. Tennessine, element 117 was the latest element claimed to be discovered, in 2009. On 28 November 2016, scientists at the IUPAC officially recognized the names for four of the newest chemical elements, with atomic numbers 113, 115, 117, and 118. The following sortable table shows the 118 known chemical elements. Chemical element A chemical element is a species of atoms having the same number of protons in their

neg: Chemistry: A Volatile History nitrogen. Rutherford came to the conclusion that the number of protons in a radioactive element "could" change – through a process of decay where parts of the nucleus are ejected from the atom. Rutherford named these fragments of ejected nucleus alpha particles. Rutherford realised that if an atom is losing protons, its identity is changing at the same time, since an atom's identity is governed by its proton number. Radioactive decay causes atoms of one element to transmute into atoms of a "different" element. He then sought to artificially engineer a specific transmutation. Rutherford fixed a source of alpha particles

neg: Periodic table found in nature. Elements 99 to 118 have only been synthesized in laboratories or nuclear reactors. The synthesis of elements having higher atomic numbers is currently being pursued: these elements would begin an eighth row, and theoretical work has been done to suggest possible candidates for this extension. Numerous synthetic radionuclides of naturally occurring elements have also been produced in laboratories. Each chemical element has a unique atomic number ("Z") representing the number of protons in its nucleus. Most elements have differing numbers of neutrons among different atoms, with these variants being referred to as isotopes. For example, carbon has

neg: Oddo–Harkins rule neutrons form the atomic nucleus, which accumulates electrons to form atoms. The number of protons in the nucleus, called atomic number, uniquely identifies a chemical element. The Oddo-Harkins rule argues that elements with odd atomic numbers have one unpaired proton and are more likely to capture another, thus increasing their atomic number. It is possible that in elements with even atomic numbers, Protons are paired, with each member of the pair balancing the spin of the other; even parity thus enhances nucleon stability. This postulate, however, does not apply to the universe's most abundant, and simplest element from the periodic

neg: Proton Proton A proton is a subatomic particle, symbol or , with a positive electric charge of +1"e" elementary charge and a mass slightly less than that of a neutron. Protons and neutrons, each with masses of approximately one atomic mass unit, are collectively referred to as "nucleons". One or more protons are present in the nucleus of every atom; they are a necessary part of the nucleus. The number of protons in the nucleus is the defining property of an element, and is referred to as the atomic number (represented by the symbol "Z"). Since each element has a unique

neg: Atom between atoms. By this mechanism, atoms are able to bond into molecules and other types of chemical compounds like ionic and covalent network crystals. By definition, any two atoms with an identical number of "protons" in their nuclei belong to the same chemical element. Atoms with equal numbers of protons but a different number of "neutrons" are different isotopes of the same element. For example, all hydrogen atoms admit exactly one proton, but isotopes exist with no neutrons (hydrogen-1, by far the most common form, also called protium), one neutron (deuterium), two neutrons (tritium) and more than two neutrons. The

neg: Mass (mass spectrometry) example, the average mass of natural water with formula HO is 1.00794 + 1.00794 + 15.9994 = 18.01528. The mass number, also called the nucleon number, is the number of protons and neutrons in an atomic nucleus. The mass number is unique for each isotope of an element and is written either after the element name or as a superscript to the left of an element's symbol. For example, carbon-12 (C) has 6 protons and 6 neutrons. The nominal mass for an element is the mass number of its most abundant naturally occurring stable isotope, and for an ion or

neg: Mass number Mass number The mass number (symbol "A", from the German word "Atomgewicht" (atomic weight), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It determines the atomic mass of atoms. Because protons and neutrons both are baryons, the mass number A is identical with the baryon number B as of the nucleus as of the whole atom or ion. The mass number is different for each different isotope of a chemical element. This is not the same as the atomic number ("Z") which denotes the

neg: Atom the nucleus defines to what chemical element the atom belongs: for example, all copper atoms contain 29 protons. The number of neutrons defines the isotope of the element. The number of electrons influences the magnetic properties of an atom. Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules. The ability of atoms to associate and dissociate is responsible for most of the physical changes observed in nature and is the subject of the discipline of chemistry. The idea that matter is made up of discrete units is a very old

neg: Chemistry: A Volatile History elements, they fuelled a scientific desire to create entirely new, artificial elements. At the beginning of the 20th century it was widely believed that atoms never change: an atom of one element stayed that way forever. Rutherford had already revealed the structure of an atom to consist mostly of empty space with a dense nucleus of protons at the centre, and Henry Mosley had shown that it is the number of protons that gives an atom its identity as a particular element. An atom of the element carbon has 6 protons, whilst an atom with 7 protons is one of

neg: Atomic number atomic numbers 1 to 118 have been observed. Synthesis of new elements is accomplished by bombarding target atoms of heavy elements with ions, such that the sum of the atomic numbers of the target and ion elements equals the atomic number of the element being created. In general, the half-life becomes shorter as atomic number increases, though an "island of stability" may exist for undiscovered isotopes with certain numbers of protons and neutrons. Atomic number The atomic number or proton number (symbol "Z") of a chemical element is the number of protons found in the nucleus of an atom. It

neg: Nuclide a specific number of protons and neutrons in the nucleus, for example carbon-13 with 6 protons and 7 neutrons. The nuclide concept (referring to individual nuclear species) emphasizes nuclear properties over chemical properties, while the isotope concept (grouping all atoms of each element) emphasizes chemical over nuclear. The neutron number has large effects on nuclear properties, but its effect on chemical reactions is negligible for most elements. Even in the case of the very lightest elements, where the ratio of neutron number to atomic number varies the most between isotopes, it usually has only a small effect, although it does

neg: Isotope the neutron numbers of these isotopes are 6, 7 and 8 respectively. A nuclide is a species of an atom with a specific number of protons and neutrons in the nucleus, for example carbon-13 with 6 protons and 7 neutrons. The "nuclide" concept (referring to individual nuclear species) emphasizes nuclear properties over chemical properties, whereas the "isotope" concept (grouping all atoms of each element) emphasizes chemical over nuclear. The neutron number has large effects on nuclear properties, but its effect on chemical properties is negligible for most elements. Even in the case of the lightest elements where the ratio of

neg: Chemical element their atomic nucleus; so the atomic number of carbon is 6. Carbon atoms may have different numbers of neutrons; atoms of the same element having different numbers of neutrons are known as isotopes of the element. The number of protons in the atomic nucleus also determines its electric charge, which in turn determines the number of electrons of the atom in its non-ionized state. The electrons are placed into atomic orbitals that determine the atom's various chemical properties. The number of neutrons in a nucleus usually has very little effect on an element's chemical properties (except in the case of

neg: Oddo–Harkins rule Oddo–Harkins rule The Oddo–Harkins rule holds that an element with an even atomic number (such as carbon: element 6) is more abundant than both elements with the adjacently smaller and larger odd atomic numbers (such as boron: element 5 and nitrogen: element 7, respectively for the carbon). This tendency of the abundance of the chemical elements was first reported by Giuseppe Oddo in 1914 and William Draper Harkins in 1917. All atoms bigger than hydrogen are formed in stars or supernovae through nucleosynthesis, when gravity, temperature and pressure reach levels high enough to fuse protons and neutrons together. Protons and

neg: Nuclear transmutation the environment. They are also mixed with larger quantities of other isotopes of the same element. Nuclear transmutation Nuclear transmutation is the conversion of one chemical element or an isotope into another chemical element. Because any element (or isotope of one) is defined by its number of protons (and neutrons) in its atoms, i.e. in the atomic nucleus, nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus is changed. A transmutation can be achieved either by nuclear reactions (in which an outside particle reacts with a nucleus) or by radioactive decay, where no

neg: Lisp (programming language) A list was a finite ordered sequence of elements, where each element is either an atom or a list, and an atom was a number or a symbol. A symbol was essentially a unique named item, written as an alphanumeric string in source code, and used either as a variable name or as a data item in symbolic processing. For example, the list contains three elements: the symbol , the list , and the number 2. The essential difference between atoms and lists was that atoms were immutable and unique. Two atoms that appeared in different places in source code

neg: Chemistry: A Volatile History elements? Scientists had recently discovered that when elements combine to form compounds, they always do so in the same proportions, by weight. John Dalton thought that for this to happen, each element had to be made of its own unique building blocks, which he called atoms. Dalton suggested that everything in the universe was made of atoms, and that there are as many kinds of atoms as there are elements, each one with its own signature weight. Based on these ideas, working completely alone, Dalton attempted to impose some order on the elements by drawing up a list, where each

neg: Chemical file format element symbols B, C, N, O, F, P, S, Cl, Br, and I. The symbol "=" represents double bonds and "#" represents triple bonds. Branching is indicated by (). Rings are indicated by pairs of digits. Some examples are The XYZ file format is a simple format that usually gives the number of atoms in the first line, a comment on the second, followed by a number of lines with atomic symbols (or atomic numbers) and cartesian coordinates. The MDL number contains a unique identification number for each reaction and variation. The format is RXXXnnnnnnnn. R indicates a reaction, XXX

neg: Nuclear transmutation Nuclear transmutation Nuclear transmutation is the conversion of one chemical element or an isotope into another chemical element. Because any element (or isotope of one) is defined by its number of protons (and neutrons) in its atoms, i.e. in the atomic nucleus, nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus is changed. A transmutation can be achieved either by nuclear reactions (in which an outside particle reacts with a nucleus) or by radioactive decay, where no outside cause is needed. Natural transmutation by stellar nucleosynthesis in the past created most of the

neg: Chemical compound compounds, and then bonds are reformed so that new associations are made between atoms. Schematically, this reaction could be described as , where A, B, C, and D are each unique atoms; and AB, AD, CD, and CB are each unique compounds. Chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds. A chemical element bonded to an identical chemical element is not a chemical compound since only one element, not two different elements, is involved. There are four types

neg: Isotope electrons in the neutral (non-ionized) atom. Each atomic number identifies a specific element, but not the isotope; an atom of a given element may have a wide range in its number of neutrons. The number of nucleons (both protons and neutrons) in the nucleus is the atom's mass number, and each isotope of a given element has a different mass number. For example, carbon-12, carbon-13 and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13 and 14 respectively. The atomic number of carbon is 6, which means that every carbon atom has 6 protons, so that

neg: Chemical element by cosmic ray spallation, and are thus rarer than heavier elements. Formation of elements with from 6 to 26 protons occurred and continues to occur in main sequence stars via stellar nucleosynthesis. The high abundance of oxygen, silicon, and iron on Earth reflects their common production in such stars. Elements with greater than 26 protons are formed by supernova nucleosynthesis in supernovae, which, when they explode, blast these elements as supernova remnants far into space, where they may become incorporated into planets when they are formed. The term "element" is used for atoms with a given number of protons (regardless

neg: Chemistry different mass numbers are known as isotopes. For example, all atoms with 6 protons in their nuclei are atoms of the chemical element carbon, but atoms of carbon may have mass numbers of 12 or 13. The standard presentation of the chemical elements is in the periodic table, which orders elements by atomic number. The periodic table is arranged in groups, or columns, and periods, or rows. The periodic table is useful in identifying periodic trends. A "compound" is a pure chemical substance composed of more than one element. The properties of a compound bear little similarity to those of

neg: History of chemistry the atomic nature of matter. In 1803, English meteorologist and chemist John Dalton proposed Dalton's law, which describes the relationship between the components in a mixture of gases and the relative pressure each contributes to that of the overall mixture. Discovered in 1801, this concept is also known as Dalton's law of partial pressures. Dalton also proposed a modern atomic theory in 1803 which stated that all matter was composed of small indivisible particles termed atoms, atoms of a given element possess unique characteristics and weight, and three types of atoms exist: simple (elements), compound (simple molecules), and complex (complex

neg: Element-reactant-product table Element-reactant-product table An element-reaction-product table is used to find coefficients while balancing an equation representing a chemical reaction. Coefficients represent moles of a substance so that the number of atoms produced is equal to the number of atoms being reacted with. This is the common setup: The layout should eventually look like this, for a balanced reaction of baking soda and vinegar (HCHO + NaHCO = NaCHO + HCO) From this, since the number of reactants for each element equals the number of products for each element, we can tell that each side is balanced in the equation. When a

neg: History of subatomic physics everything known in modern physics. In the 19th century, John Dalton, through his work on stoichiometry, concluded that each chemical element was composed of a single, unique type of particle. Dalton and his contemporaries believed those were the fundamental particles of nature and thus named them atoms, after the Greek word "atomos", meaning "indivisible" or "uncut". However, near the end of 19th century, physicists discovered that Dalton's atoms are not, in fact, the fundamental particles of nature, but conglomerates of even smaller particles. Electron was discovered between 1879 and 1897 in works of William Crookes, Arthur Schuster, J. J. Thomson,

neg: X-ray photoelectron spectroscopy molecular species using helium lamps. A typical XPS spectrum is a plot of the number of electrons detected (sometimes per unit time) ("Y"-axis, ordinate) versus the binding energy of the electrons detected ("X"-axis, abscissa). Each element produces a characteristic set of XPS peaks at characteristic binding energy values that directly identify each element that exists in or on the surface of the material being analyzed. These characteristic spectral peaks correspond to the electron configuration of the electrons within the atoms, e.g., 1"s", 2"s", 2"p", 3"s", etc. The number of detected electrons in each of the characteristic peaks is directly related

neg: Element-reactant-product table this:<br> Because of the coefficients, the equation is balanced. Element-reactant-product table An element-reaction-product table is used to find coefficients while balancing an equation representing a chemical reaction. Coefficients represent moles of a substance so that the number of atoms produced is equal to the number of atoms being reacted with. This is the common setup: The layout should eventually look like this, for a balanced reaction of baking soda and vinegar (HCHO + NaHCO = NaCHO + HCO) From this, since the number of reactants for each element equals the number of products for each element, we can tell that

neg: Environmental isotopes Environmental isotopes The environmental isotopes are a subset of the isotopes, both stable and radioactive, which are the object of isotope geochemistry. They are primarily used as tracers to see how things move around within the ocean-atmosphere system, within terrestrial biomes, within the Earth's surface, and between these broad domains. Chemical elements are defined by their number of protons, but the mass of the atom is determined by the number of protons and neutrons in the nucleus. Isotopes are atoms that are of a specific element, but have different numbers of neutrons and thus different masses. In a specific object,

neg: Atomic mass strongly-bound compared with other atoms, the mass defect of binding for most atoms is an even smaller fraction of a dalton (unified atomic mass unit, based on carbon-12). Since free protons and neutrons differ from each other in mass by a small fraction of a dalton (about 0.0014 u), rounding the relative isotopic mass, or the atomic mass of any given nuclide given in daltons to the nearest whole number always gives the nucleon count, or mass number. Additionally, the neutron count (neutron number) may then be derived by subtracting the number of protons (atomic number) from the mass number

neg: Isotope Isotope Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in mass number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom. The term isotope is formed from the Greek roots isos (ἴσος "equal") and topos (τόπος "place"), meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element occupy the same position on the periodic table. The number of protons within the atom's nucleus is called atomic number and is equal to the number of

neg: Atomic radius they provided important evidence for the development and confirmation of quantum theory. The atomic radii decrease across the Periodic Table because as the atomic number increases, the number of protons increases across the period, but the extra electrons are only added to the same quantum shell. Therefore, the effective nuclear charge towards the outermost electrons increases, drawing the outermost electrons closer. As a result, the electron cloud contracts and the atomic radius decreases. In 1920, shortly after it had become possible to determine the sizes of atoms using X-ray crystallography, it was suggested that all atoms of the same element

neg: Isobar (nuclide) Isobar (nuclide) Isobars are atoms (nuclides) of different chemical elements that have the same number of nucleons. Correspondingly, isobars differ in atomic number (or number of protons) but have the same mass number. An example of a series of isobars would be S, Cl, Ar, K, and Ca. The nuclei of these nuclides all contain 40 nucleons; however, they contain varying numbers of protons and neutrons. The term "isobars" (originally "isobares") for nuclides was suggested by Alfred Walter Stewart in 1918. It is derived from the Greek word "isos", meaning "equal" and "baros", meaning "weight". The same mass number implies

neg: Neutron Neutron The neutron is a subatomic particle, symbol or , with no net electric charge and a mass slightly larger than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behave similarly within the nucleus, and each has a mass of approximately one atomic mass unit, they are both referred to as nucleons. Their properties and interactions are described by nuclear physics. The chemical and nuclear properties of the nucleus are determined by the number of protons, called the atomic number, and the number of neutrons, called the neutron number. The atomic mass

neg: Chemical substance can be transmuted into another element through a nuclear reaction. This is so, because all of the atoms in a sample of an element have the same number of protons, though they may be different isotopes, with differing numbers of neutrons. As of 2012, there are 118 known elements, about 80 of which are stable – that is, they do not change by radioactive decay into other elements. Some elements can occur as more than a single chemical substance (allotropes). For instance, oxygen exists as both diatomic oxygen (O) and ozone (O). The majority of elements are classified as metals.

neg: Atomic spectroscopy electron to a higher energy level (higher orbital) and/or the energy emitted as the electron moves to a lower energy level is absorbed or emitted in the form of photons (light particles). Because each element has a unique number of electrons, an atom will absorb/release energy in a pattern unique to its elemental identity (e.g. Ca, Na, etc.) and thus will absorb/emit photons in a correspondingly unique pattern. The type of atoms present in a sample, or the amount of atoms present in a sample can be deduced from measuring these changes in light wavelength and light intensity. Optical spectroscopy

neg: Particle physics century, John Dalton, through his work on stoichiometry, concluded that each element of nature was composed of a single, unique type of particle. The word "atom", after the Greek word "atomos" meaning "indivisible", has since then denoted the smallest particle of a chemical element, but physicists soon discovered that atoms are not, in fact, the fundamental particles of nature, but are conglomerates of even smaller particles, such as the electron. The early 20th century explorations of nuclear physics and quantum physics led to proofs of nuclear fission in 1939 by Lise Meitner (based on experiments by Otto Hahn), and nuclear

neg: Atom one stable isotope exists. As a rule, there is only a handful of stable isotopes for each of these elements, the average being 3.2 stable isotopes per element. Twenty-six elements have only a single stable isotope, while the largest number of stable isotopes observed for any element is ten, for the element tin. Elements 43, 61, and all elements numbered 83 or higher have no stable isotopes. Stability of isotopes is affected by the ratio of protons to neutrons, and also by the presence of certain "magic numbers" of neutrons or protons that represent closed and filled quantum shells. These

neg: P-process of the next element. This led to the original idea for the production of p-nuclei: free protons (the nuclei of hydrogen atoms are present in stellar plasmas) should be captured on heavy nuclei ("seed nuclei") also already present in the stellar plasma (previously produced in the s- and/or r-process). Such proton captures on stable nuclides (or nearly stable), however, are not very efficient in producing p-nuclei, especially the heavier ones, because the electric charge increases with each added proton, leading to an increased repulsion of the next proton to be added, according to Coulomb's law. In the context of nuclear

neg: Boron porphyrins differences between p-block-element-centered porphyrins and transition-metal-centered porphyrins is the far smaller size of the interstitial atom, especially in the case of the first-row p-block. Other than protons, the next smallest atom known to bind to the central N pocket is lithium. The first two isolated lithium porphyrin complexes each reported a 2:1 metal to base ratio, and XRD suggested both lithium atoms reside out of the porphyrin plane. Boron has a covalent radius of 85 pm, significantly smaller than lithium's 133 pm. This suggests the porphyrin pocket is more likely to accommodate two boron atoms rather than one. Indeed, each

neg: Boolean algebras canonically defined algebra of finite sets and their complements and therefore atomic. This example is isomorphic to the direct product of Examples 4 and 5, furnishing another description of it. Example 8. The direct product of a Periodic Sequence (Example 5) with any finite but nontrivial Boolean algebra. (The trivial one-element Boolean algebra is the unique finite atomless Boolean algebra.) This resembles Example 7 in having both atoms and an atomless subalgebra, but differs in having only finitely many atoms. Example 8 is in fact an infinite family of examples, one for each possible finite number of atoms. These examples by no

neg: Migma repel each other due to the electrostatic force. In order for fusion to occur, the nuclei must have enough energy to overcome this coulomb barrier. The barrier is lowered for atoms with less positive charge, those with the fewest number of protons, and the strong force is increased with additional nucleons, the total number of protons and neutrons. This means that a combination of deuterium and tritium has the lowest coulomb barrier, at about 100 keV (see requirements for fusion). When the fuel is heated to high energies the electrons disassociate from the nuclei, which are left as ions in

neg: Atom (see below). The heaviest stable atom is lead-208, with a mass of . As even the most massive atoms are far too light to work with directly, chemists instead use the unit of moles. One mole of atoms of any element always has the same number of atoms (about ). This number was chosen so that if an element has an atomic mass of 1 u, a mole of atoms of that element has a mass close to one gram. Because of the definition of the unified atomic mass unit, each carbon-12 atom has an atomic mass of exactly 12

neg: Word (group theory) is any expression of the form where "s"...,"s" are elements of "S" and each "ε" is ±1. The number "n" is known as the length of the word. Each word in "S" represents an element of "G", namely the product of the expression. By convention, the identity (unique) element can be represented by the empty word, which is the unique word of length zero. When writing words, it is common to use exponential notation as an abbreviation. For example, the word could be written as This latter expression is not a word itself—it is simply a shorter notation for the

neg: Atomic radius the next outer shell, accounting for the sudden increase in the atomic radius. The increasing nuclear charge is partly counterbalanced by the increasing number of electrons, a phenomenon that is known as shielding; which explains why the size of atoms usually increases down each column. However, there is one notable exception, known as the lanthanide contraction: the 5d block of elements are much smaller than one would expect, due to the shielding caused by the 4f electrons. Essentially, atomic radius decreases across the periods due to an increasing number of protons. Therefore, there is a greater attraction between the protons

neg: Periodic table three naturally occurring isotopes: all of its atoms have six protons and most have six neutrons as well, but about one per cent have seven neutrons, and a very small fraction have eight neutrons. Isotopes are never separated in the periodic table; they are always grouped together under a single element. Elements with no stable isotopes have the atomic masses of their most stable isotopes, where such masses are shown, listed in parentheses. In the standard periodic table, the elements are listed in order of increasing atomic number "Z" (the number of protons in the nucleus of an atom). A

neg: Characteristic X-ray Characteristic X-ray Characteristic X-rays are emitted when outer-shell electrons fill a vacancy in the inner shell of an atom, releasing X-rays in a pattern that is "characteristic" to each element. Characteristic X-rays were discovered by Charles Glover Barkla in 1909, who later won the Nobel Prize in Physics for his discovery in 1917. Characteristic X-rays are produced when an element is bombarded with high-energy particles, which can be photons, electrons or ions (such as protons). When the incident particle strikes a bound electron (the target electron) in an atom, the target electron is ejected from the inner shell of the

neg: Proton in interaction with any type of normal (non-plasma) matter, low-velocity free protons are attracted to electrons in any atom or molecule with which they come in contact, causing the proton and molecule to combine. Such molecules are then said to be "protonated", and chemically they often, as a result, become so-called Brønsted acids. In chemistry, the number of protons in the nucleus of an atom is known as the atomic number, which determines the chemical element to which the atom belongs. For example, the atomic number of chlorine is 17; this means that each chlorine atom has 17 protons and

neg: Isotopes of beryllium Isotopes of beryllium Beryllium (Be) has 12 known isotopes, but only one of these isotopes () is stable and a primordial nuclide. As such, beryllium is considered a monoisotopic element. It is also a mononuclidic element, because its other isotopes have such short half-lives that none are primordial and their abundance is very low (standard atomic weight is 9.0122). Beryllium is unique as being the only monoisotopic element with both an even number of protons and an odd number of neutrons. There are 25 other monoisotopic elements but all have odd atomic numbers, and even numbers of neutrons. Of the

neg: Ion transferred to the electron-deficient nonmetal atoms. This reaction produces metal cations and nonmetal anions, which are attracted to each other to form a "salt". Ion An ion () is an atom or molecule that has a non-zero net electrical charge. Since the charge of the electron (considered "negative" by convention) is equal and opposite to that of the proton (considered "positive" by convention), the net charge of an ion is non-zero due to its total number of electrons being unequal to its total number of protons. A cation is a positively charged ion, with fewer electrons than protons, while an

neg: Atomic theory of the 20th century, through various experiments with electromagnetism and radioactivity, physicists discovered that the so-called "uncuttable atom" was actually a conglomerate of various subatomic particles (chiefly, electrons, protons and neutrons) which can exist separately from each other. In fact, in certain extreme environments, such as neutron stars, extreme temperature and pressure prevents atoms from existing at all. Since atoms were found to be divisible, physicists later invented the term "elementary particles" to describe the "uncuttable", though not indestructible, parts of an atom. The field of science which studies subatomic particles is particle physics, and it is in this field

neg: Deeper, Deeper, Deeper Still comet orchid with pollen far within the flower. He further demonstrates that scents from flowers are used to trigger olfactory centers in the brain, stimulating the mind to threats as to aid in the survival of the species. Tyson narrates how Greek philosophers Thales and Democritus postulated that all matter was made up of combinations of atoms in a large number of configurations, and describes how carbon serves as the basic building block for life on Earth due to its unique chemical nature. Tyson examines the basic structure of atoms, their protons, neutrons, and electrons, and the nature of nuclear

neg: Radioactive decay decaying nucleus is called the "parent radionuclide" (or "parent radioisotope"), and the process produces at least one "daughter nuclide". Except for gamma decay or internal conversion from a nuclear excited state, the decay is a nuclear transmutation resulting in a daughter containing a different number of protons or neutrons (or both). When the number of protons changes, an atom of a different chemical element is created. The first decay processes to be discovered were alpha decay, beta decay, and gamma decay. Alpha decay occurs when the nucleus ejects an alpha particle (helium nucleus). This is the most common process of

neg: Nuclear power of energy generated when compared to the other major energy producing methods. Coal, petroleum, natural gas and hydroelectricity each have caused a greater number of fatalities per unit of energy, due to air pollution and accidents. Collaboration on research and development towards greater efficiency, safety and recycling of spent fuel in future Generation IV reactors presently includes Euratom and the co-operation of more than 10 permanent countries globally. In 1932 physicist Ernest Rutherford discovered that when lithium atoms were "split" by protons from a proton accelerator, immense amounts of energy were released in accordance with the principle of mass–energy equivalence.

neg: Nuclear fission are therefore usually unstable to beta decay (which changes neutrons to protons) because they have proportionally too many neutrons compared to stable isotopes of similar mass. This tendency for fission product nuclei to beta-decay is the fundamental cause of the problem of radioactive high level waste from nuclear reactors. Fission products tend to be beta emitters, emitting fast-moving electrons to conserve electric charge, as excess neutrons convert to protons in the fission-product atoms. See Fission products (by element) for a description of fission products sorted by element. Several heavy elements, such as uranium, thorium, and plutonium, undergo both spontaneous fission,

neg: Resonance ionization for the first time, the resonance ionization process on helium atoms. They wanted to use laser light to measure the number of singlet metastable helium, He (2S), particles created from energetic protons. The group achieved the selective ionization of the excited state of an atom at nearly 100% efficiency by using pulsed laser light to pass a beam of protons into the helium gas cell. The experiment on singlet metastable helium atoms was seminal in the journey towards using resonance ionization spectroscopy (RIS) for extensive atomic analysis in research settings. Cesium atoms was subsequently used to show that single atoms

neg: Mirror nuclei Mirror nuclei Mirror nuclei are nuclei where the number of protons of element one (Z) equals the number of neutrons of element two (N) and the number of protons of element two (Z) equals the number of neutrons in element one (N), such that the mass number is the same (A = N + Z = N + Z). As that Z = N and Z = N, A = N + N = Z + Z. By making the substitution Z = Z and Z = Z − 1, the mass number can be rewritten in the form 2Z

neg: Valley of stability atomic and neutron numbers, forming what has been called an island of stability outside of the valley of stability. All atomic nuclei are composed of protons and neutrons bound together by the nuclear force. There are 287 different nuclei that occur naturally on earth, each corresponding to a unique number of protons, called the atomic number, Z, and a unique number of neutrons, called the neutron number, N. The mass number, A, of a nuclide is the sum of atomic and neutron numbers, A=Z+N. Not all nuclides are stable, however. According to Byrne, stable nuclides are defined as those having

neg: Bohr model (see Electron shell and the later discussion of the "Shell Model of the Atom" below). This was established empirically before Bohr presented his model. Bohr extended the model of hydrogen to give an approximate model for heavier atoms. This gave a physical picture that reproduced many known atomic properties for the first time. Heavier atoms have more protons in the nucleus, and more electrons to cancel the charge. Bohr's idea was that each discrete orbit could only hold a certain number of electrons. After that orbit is full, the next level would have to be used. This gives the atom

neg: Atomic theory hydrogen atoms - then assumed to be the lightest particles - led him to conclude that hydrogen nuclei were singular particles and a basic constituent of all atomic nuclei. He named such particles protons. Further experimentation by Rutherford found that the nuclear mass of most atoms exceeded that of the protons it possessed; he speculated that this surplus mass was composed of previously-unknown neutrally charged particles, which were tentatively dubbed "neutrons". In 1928, Walter Bothe observed that beryllium emitted a highly penetrating, electrically neutral radiation when bombarded with alpha particles. It was later discovered that this radiation could knock hydrogen

neg: Coxeter matroid a unique minimal element with respect to the "w"-Bruhat order. Suppose that the Coxeter group "W" is the symmetric group "S" and "P" is the parabolic subgroup "S"×"S". Then "W"/"P" can be identified with the "k"-element subsets of the "n"-element set {1,2...,"n"} and the elements "w" of "W" correspond to the linear orderings of this set. A Coxeter matroid consists of "k" elements sets such that for each "w" there is a unique minimal element in the corresponding Bruhat ordering of "k"-element subsets. This is exactly the definition of a matroid of rank "k" on an "n"-element set in terms

neg: Monoisotopic element nuclear pairing effects, the odd number of protons imparts instability to isotopes of an odd "Z", which in heavier elements requires a completely paired set of neutrons to offset this tendency into stability. (The four stable nuclides with odd "Z" and odd neutron numbers are hydrogen-2, lithium-6, boron-10, and nitrogen-14.) The single mononuclidic exception to the odd "Z" rule is beryllium, which has 4 protons and 5 neutrons. This element is prevented from having equal numbers of neutrons and protons (4 of each) by the instability toward alpha decay, which is favored due to the extremely tight binding of helium-4

neg: Nickel in ice and sediment. Nickel-78's half-life was recently measured at 110 milliseconds, and is believed an important isotope in supernova nucleosynthesis of elements heavier than iron. The nuclide Ni, discovered in 1999, is the most proton-rich heavy element isotope known. With 28 protons and 20 neutrons Ni is "double magic", as is with 28 protons and 50 neutrons. Both are therefore unusually stable for nuclides with so large a proton-neutron imbalance. On Earth, nickel occurs most often in combination with sulfur and iron in pentlandite, with sulfur in millerite, with arsenic in the mineral nickeline, and with arsenic and sulfur

neg: Spin quantum number +1/2 the atom moves away from the stronger field, and when the spin is −1/2 the atom moves toward it. Thus the beam of silver atoms is split while traveling through the in-homogeneous magnetic field, according to the spin of each atom's valence electron. In 1927 Phipps and Taylor conducted a similar experiment, using atoms of hydrogen with similar results. Later scientists conducted experiments using other atoms that have only one electron in their valence shell: (copper, gold, sodium, potassium). Every time there two lines formed on the metallic plate. The atomic nucleus also may have spin, but protons and

neg: Quantum number the same system by 8 states that are eigenvectors of the Hamiltonian (i.e. each represents a state that does not mix with others over time), we should consider the following 8 states: In nuclei, the entire assembly of protons and neutrons (nucleons) has a resultant angular momentum due to the angular momenta of each nucleon, usually denoted ". If the total angular momentum of a neutron is "j" = + "s" and for a proton is "j" = + "s" (where "s" for protons and neutrons happens to be ½ again) then the nuclear angular momentum quantum numbers are given

neg: Nuclear Power and the Environment radiation to aid in later chapters. The first half covers the basics on atoms such as: an atom consists of Neutrons, Protons, and Electrons; the atomic number of an atom determines the amount of protons in one atom; and that protons are roughly 2000 times heavier than electrons (see atom). The concept of radiation is introduced through ionization which is the process of adding one or more electrons to, or removing one or more electrons from, atoms or molecules, thereby creating ions. From there certain particles can cause ionization. The ionizing particles are alpha particles (a type of ionizing radiation

neg: Albert Ghiorso the first new element to be discovered atom-by-atom. The recoil technique invented by Ghiorso was crucial to obtaining an identifiable signal from individual atoms of the new element. In the mid-1950s it became clear that to extend the periodic chart any further, a new accelerator would be needed, and the Berkeley Heavy Ion Linear Accelerator (HILAC) was built, with Ghiorso in charge. That machine was used in the discovery of elements 102-106 (102, nobelium; 103, lawrencium; 104, rutherfordium; 105, dubnium and 106, seaborgium), each produced and identified on the basis of only a few atoms. The discovery of each successive

neg: Abraham Alikhanov and. M. S. Kozodaev, he discovered and studied the phenomenon of the emission of electron-positron pairs by excited nuclei. In 1935, with Alikhanian, he established the dependence of β-spectra on the atomic number of an element. In 1936, working with Alikhanian and L. A. Artsimovich, he experimentally corroborated the law of conservation of momentum in pair annihilation. The research initiated by Alikhanov, Alikhanian, and S. Ia. Nikitin led to the discovery in 1939 of a stream of fast protons in cosmic rays. In 1949 Alikhanov founded the first nuclear reactor in the USSR. In 1961, with V. V. Vladimirskii and

neg: Xenon from the decay of mantle-derived gases from soon after Earth's formation. After Neil Bartlett's discovery in 1962 that xenon can form chemical compounds, a large number of xenon compounds have been discovered and described. Almost all known xenon compounds contain the electronegative atoms fluorine or oxygen. The chemistry of xenon in each oxidation state is analogous to that of the neighboring element iodine in the immediately lower oxidation state. Three fluorides are known: , , and . XeF is theorized to be unstable. These are the starting points for the synthesis of almost all xenon compounds. The solid, crystalline difluoride

neg: Atom a result, no antimatter atoms have been discovered in nature. However, in 1996 the antimatter counterpart of the hydrogen atom (antihydrogen) was synthesized at the CERN laboratory in Geneva. Other exotic atoms have been created by replacing one of the protons, neutrons or electrons with other particles that have the same charge. For example, an electron can be replaced by a more massive muon, forming a muonic atom. These types of atoms can be used to test the fundamental predictions of physics. Atom An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical

neg: Radiometric dating are accurate and the materials to which they can be applied. All ordinary matter is made up of combinations of chemical elements, each with its own atomic number, indicating the number of protons in the atomic nucleus. Additionally, elements may exist in different isotopes, with each isotope of an element differing in the number of neutrons in the nucleus. A particular isotope of a particular element is called a nuclide. Some nuclides are inherently unstable. That is, at some point in time, an atom of such a nuclide will undergo radioactive decay and spontaneously transform into a different nuclide. This

neg: Isotopic labeling different isotope (like a radioactive isotope used in radioactive tracing). Because the labeled atom has the same number of protons, it will behave in almost exactly the same way as its unlabeled counterpart and, with few exceptions, will not interfere with the reaction under investigation. The difference in the number of neutrons, however, means that it can be detected separately from the other atoms of the same element. Nuclear magnetic resonance (NMR) and mass spectrometry (MS) are used to investigate the mechanisms of chemical reactions. NMR and MS detects isotopic differences, which allows information about the position of the labeled

neg: Atomic mass more significant figures than atomic weights. Standard atomic weight is related to atomic mass by the abundance ranking of isotopes for each element. It is usually "about" the same value as the atomic mass of the most abundant isotope, other than what looks like (but is not actually) a rounding difference. The atomic mass of atoms, ions, or atomic nuclei is slightly less than the sum of the masses of their constituent protons, neutrons, and electrons, due to binding energy mass loss (as per "E"="mc"). Relative "isotopic" mass (a property of a single atom) is not to be confused with

neg: Permutation model of subsets of "A" containing all elements of "A". Here an ideal is a collection "I" of subsets of "A" closed under taking unions and subsets, and is called invariant if it is invariant under the action of the group "G". For each element "S" of the ideal one can take the subgroup of "G" consisting of all elements fixing every element "S". These subgroups generate a normal filter of "G". Permutation model In mathematical set theory, a permutation model is a model of set theory with atoms (ZFA) constructed using a group of permutations of the atoms. A symmetric

neg: Atom neutrons can potentially drop to a lower energy state through a radioactive decay that causes the number of protons and neutrons to more closely match. As a result, atoms with matching numbers of protons and neutrons are more stable against decay. However, with increasing atomic number, the mutual repulsion of the protons requires an increasing proportion of neutrons to maintain the stability of the nucleus, which slightly modifies this trend of equal numbers of protons to neutrons. The number of protons and neutrons in the atomic nucleus can be modified, although this can require very high energies because of the

neg: Thermodynamic system is the number of atoms of element "i" in molecule "j" and "b" is the total number of atoms of element "i" in the system, which remains constant, since the system is closed. There is one such equation for each element in the system. An isolated system is more restrictive than a closed system as it does not interact with its surroundings in any way. Mass and energy remains constant within the system, and no energy or mass transfer takes place across the boundary. As time passes in an isolated system, internal differences in the system tend to even out

neg: Isotope Uranium isotopes have been separated in bulk by gas diffusion, gas centrifugation, laser ionization separation, and (in the Manhattan Project) by a type of production mass spectrometry. Isotope Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in mass number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom. The term isotope is formed from the Greek roots isos (ἴσος "equal") and topos (τόπος "place"), meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element

neg: Chemical element element cannot be transformed into other chemical elements by chemical processes. Elements during this time were generally distinguished by their atomic weights, a property measurable with fair accuracy by available analytical techniques. The 1913 discovery by English physicist Henry Moseley that the nuclear charge is the physical basis for an atom's atomic number, further refined when the nature of protons and neutrons became appreciated, eventually led to the current definition of an element based on atomic number (number of protons per atomic nucleus). The use of atomic numbers, rather than atomic weights, to distinguish elements has greater predictive value (since

neg: Lunar water theorized that the latter may occur when hydrogen ions (protons) in the solar wind chemically combine with the oxygen atoms present in the lunar minerals (oxides, silicates etc.) to produce small amounts of water trapped in the minerals' crystal lattices or as hydroxyl groups, potential water precursors. (This mineral-bound water, or hydroxylated mineral surface, must not be confused with water ice.) The hydroxyl surface groups (S–OH) formed by the reaction of protons (H) with oxygen atoms accessible at oxide surface (S=O) could further be converted in water molecules (HO) adsorbed onto the oxide mineral's surface. The mass balance of a

neg: Alpha particle less likely to be referred to as "alpha particles". The best-known source of alpha particles is alpha decay of heavier (> 106 u atomic weight) atoms. When an atom emits an alpha particle in alpha decay, the atom's mass number decreases by four due to the loss of the four nucleons in the alpha particle. The atomic number of the atom goes down by exactly two, as a result of the loss of two protons – the atom becomes a new element. Examples of this sort of nuclear transmutation are when uranium becomes thorium, or radium becomes radon gas, due

neg: Mass number number of protons in a nucleus, and thus uniquely identifies an element. Hence, the difference between the mass number and the atomic number gives the number of neutrons ("N") in a given nucleus: . The mass number is written either after the element name or as a superscript to the left of an element's symbol. For example, the most common isotope of carbon is carbon-12, or , which has 6 protons and 6 neutrons. The full isotope symbol would also have the atomic number ("Z") as a subscript to the left of the element symbol directly below the mass number:

neg: Atom or positive charge, respectively, and it is called an ion. The electrons of an atom are attracted to the protons in an atomic nucleus by this electromagnetic force. The protons and neutrons in the nucleus are attracted to each other by a different force, the nuclear force, which is usually stronger than the electromagnetic force repelling the positively charged protons from one another. Under certain circumstances, the repelling electromagnetic force becomes stronger than the nuclear force, and nucleons can be ejected from the nucleus, leaving behind a different element: nuclear decay resulting in nuclear transmutation. The number of protons in

neg: Chemical equilibrium where "a" is the number of atoms of element "i" in molecule "j" and "b" is the total number of atoms of element "i", which is a constant, since the system is closed. If there are a total of "k" types of atoms in the system, then there will be "k" such equations. If ions are involved, an additional row is added to the a matrix specifying the respective charge on each molecule which will sum to zero. This is a standard problem in optimisation, known as constrained minimisation. The most common method of solving it is using the method

neg: Isotope dilution employs signal ratios. Owing to both of these advantages, the method of isotope dilution is regarded among chemistry measurement methods of the highest metrological standing. What is Isotope? Isotopes are variants of a particular chemical element which differ in neutron number. All isotopes of a given element have the same number of protons in each atom. The term isotope is formed from the Greek roots isos (ἴσος "equal") and topos (τόπος "place"), meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element occupy the same position on the periodic table. Analytical application

neg: Closed system closed system amounts to a constant number of particles. However, for systems which are undergoing a chemical reaction, there may be all sorts of molecules being generated and destroyed by the reaction process. In this case, the fact that the system is closed is expressed by stating that the total number of each elemental atom is conserved, no matter what kind of molecule it may be a part of. Mathematically: formula_1 where formula_2 is the number of j-type molecules, formula_3 is the number of atoms of element "i" in molecule "j" and "b" is the total number of atoms of

neg: Stoichiometry element must be the same throughout the overall reaction. For example, the number of atoms of a given element X on the reactant side must equal the number of atoms of that element on the product side, whether or not all of those atoms are actually involved in a reaction. Chemical reactions, as macroscopic unit operations, consist of simply a very large number of elementary reactions, where a single molecule reacts with another molecule. As the reacting molecules (or moieties) consist of a definite set of atoms in an integer ratio, the ratio between reactants in a complete reaction is

neg: Formula |}{\underset{\underset{\underset{| \atop \displaystyle H}{C}}-H</chem>|caption=The structural formula for butane. There are three common non-pictorial types of chemical formulas for this molecule: A chemical formula identifies each constituent element by its chemical symbol and indicates the proportionate number of atoms of each element. In empirical formulas, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, as ratios to the key element. For molecular compounds, these ratio numbers can all be expressed as whole numbers. For example, the empirical formula of ethanol may be written CHO because the molecules of ethanol all

neg: Canonical S-expressions used to surround atoms that contain spaces, when using the canonical encoding each atom is encoded as a length-prefixed byte string. No whitespace separating adjacent elements in a list is permitted. The length of an atom is expressed as an ASCII decimal number followed by a ":". The sexp becomes the csexp Note that no quotation marks are required to escape the space character internal to the atom "Canonical S-expression", because the length prefix clearly points to the end of the atom. Note also that there is no whitespace separating an atom from the next element in the list. While