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  2. Atom (measure theory) - Wikipedia

    en.wikipedia.org/wiki/Atom_(measure_theory)

    Consider the set X = {1, 2, ..., 9, 10} and let the sigma-algebra be the power set of X. Define the measure of a set to be its cardinality, that is, the number of elements in the set. Then, each of the singletons {i}, for i = 1, 2, ..., 9, 10 is an atom. Consider the Lebesgue measure on the real line. This measure has no atoms.

  3. IUPAC numerical multiplier - Wikipedia

    en.wikipedia.org/wiki/IUPAC_numerical_multiplier

    The numbers 200-900 would be confused easily with 22 to 29 if they were used in chemistry. khīlioi = 1000, diskhīlioi = 2000, triskhīlioi = 3000, etc. 13 to 19 are formed by starting with the Greek word for the number of ones, followed by και (the Greek word for 'and'), followed by δέκα (the Greek word for 'ten').

  4. Coordination number - Wikipedia

    en.wikipedia.org/wiki/Coordination_number

    In chemistry, crystallography, and materials science, the coordination number, also called ligancy, of a central atom in a molecule or crystal is the number of atoms, molecules or ions bonded to it. The ion/molecule/atom surrounding the central ion/molecule/atom is called a ligand. This number is determined somewhat differently for molecules ...

  5. Electron counting - Wikipedia

    en.wikipedia.org/wiki/Electron_counting

    Neutral counting assumes each bond is equally split between two atoms. This method begins with locating the central atom on the periodic table and determining the number of its valence electrons. One counts valence electrons for main group elements differently from transition metals, which use d electron count .

  6. List of chemistry mnemonics - Wikipedia

    en.wikipedia.org/wiki/List_of_chemistry_mnemonics

    An atom (or ion) whose oxidation number increases in a redox reaction is said to be oxidized (and is called a reducing agent). It is accomplished by loss of one or more electrons. The atom whose oxidation number decreases gains (receives) one or more electrons and is said to be reduced. This relation can be remembered by the following mnemonics.

  7. Atomicity (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Atomicity_(chemistry)

    Atomicity is the total number of atoms present in a molecule of an element. For example, each molecule of oxygen (O 2) is composed of two oxygen atoms. Therefore, the atomicity of oxygen is 2. [1] In older contexts, atomicity is sometimes equivalent to valency. Some authors also use the term to refer to the maximum number of valencies observed ...

  8. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    The Earth contains approximately 1.33 × 10 50 atoms. [135] Although small numbers of independent atoms of noble gases exist, such as argon, neon, and helium, 99% of the atmosphere is bound in the form of molecules, including carbon dioxide and diatomic oxygen and nitrogen.

  9. Pólya enumeration theorem - Wikipedia

    en.wikipedia.org/wiki/Pólya_enumeration_theorem

    where n is the number of elements of X and c k (g) is the number of k-cycles of the group element g as a permutation of X. A colored arrangement is an orbit of the action of G on the set Y X (where Y is the set of colors and Y X denotes the set of all functions φ: X→Y).