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  2. Zero to the power of zero - Wikipedia

    en.wikipedia.org/wiki/Zero_to_the_power_of_zero

    The combinatorial interpretation of b 0 is the number of 0-tuples of elements from a b-element set; there is exactly one 0-tuple. The set-theoretic interpretation of b 0 is the number of functions from the empty set to a b-element set; there is exactly one such function, namely, the empty function. [1] All three of these specialize to give 0 0 = 1.

  3. Electronegativity - Wikipedia

    en.wikipedia.org/wiki/Electronegativity

    where ε s,p are the one-electron energies of s- and p-electrons in the free atom and n s,p are the number of s- and p-electrons in the valence shell. It is usual to apply a scaling factor, 1.75×10 −3 for energies expressed in kilojoules per mole or 0.169 for energies measured in electronvolts, to give values that are numerically similar to ...

  4. Atomic number - Wikipedia

    en.wikipedia.org/wiki/Atomic_number

    The atomic number or nuclear charge number (symbol Z) of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number (np) or the number of protons found in the nucleus of every atom of that element. The atomic number can be used to uniquely identify ...

  5. Electron configuration - Wikipedia

    en.wikipedia.org/wiki/Electron_configuration

    Electron configuration. In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. [1] For example, the electron configuration of the neon atom is 1s2 2s2 2p6, meaning that the 1s, 2s, and 2p subshells are occupied by ...

  6. Ionization energy - Wikipedia

    en.wikipedia.org/wiki/Ionization_energy

    Ionization energy is positive for neutral atoms, meaning that the ionization is an endothermic process. Roughly speaking, the closer the outermost electrons are to the nucleus of the atom, the higher the atom's ionization energy. In physics, ionization energy is usually expressed in electronvolts (eV) or joules (J).

  7. Electron affinity - Wikipedia

    en.wikipedia.org/wiki/Electron_affinity

    The electron affinity (Eea) of an atom or molecule is defined as the amount of energy released when an electron attaches to a neutral atom or molecule in the gaseous state to form an anion. X (g) + e − → X − (g) + energy. This differs by sign from the energy change of electron capture ionization. [1] The electron affinity is positive when ...

  8. Hund's rules - Wikipedia

    en.wikipedia.org/wiki/Hund's_rules

    The multiplicity is equal to + , where is the total spin angular momentum for all electrons. The multiplicity is also equal to the number of unpaired electrons plus one. [ 4 ] Therefore, the term with lowest energy is also the term with maximum S {\displaystyle S\,} and maximum number of unpaired electrons with equal spin angular momentum ...

  9. List of elements by atomic properties - Wikipedia

    en.wikipedia.org/wiki/List_of_elements_by_atomic...

    This is a list of chemical elements and their atomic properties, ordered by Atomic number.. Since valence electrons are not clearly defined for the d-block and f-block elements, there not being a clear point at which further ionisation becomes unprofitable, a purely formal definition as number of electrons in the outermost shell has been used.