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  2. 18-electron rule - Wikipedia

    en.wikipedia.org/wiki/18-electron_rule

    The rule is based on the fact that the valence orbitals in the electron configuration of transition metals consist of five (n−1)d orbitals, one ns orbital, and three np orbitals, where n is the principal quantum number. These orbitals can collectively accommodate 18 electrons as either bonding or non-bonding electron pairs.

  3. Valence electron - Wikipedia

    en.wikipedia.org/wiki/Valence_electron

    The number of valence electrons of an element can be determined by the periodic table group (vertical column) in which the element is categorized. In groups 1–12, the group number matches the number of valence electrons; in groups 13–18, the units digit of the group number matches the number of valence electrons. (Helium is the sole ...

  4. Electron configurations of the elements (data page) - Wikipedia

    en.wikipedia.org/wiki/Electron_configurations_of...

    The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Dordrecht, The Netherlands: Springer Science+Business Media. p. 1722. ISBN 1-4020-3555-1. This book contains predicted electron configurations for the elements up to 172, as well as 184, based on relativistic Dirac–Fock calculations by B. Fricke in Fricke, B. (1975). Dunitz ...

  5. Valence (chemistry) - Wikipedia

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

    The valence is the combining capacity of an atom of a given element, determined by the number of hydrogen atoms that it combines with. In methane, carbon has a valence of 4; in ammonia, nitrogen has a valence of 3; in water, oxygen has a valence of 2; and in hydrogen chloride, chlorine has a valence of 1.

  6. Periodic table - Wikipedia

    en.wikipedia.org/wiki/Periodic_table

    Elements in the same column have the same number of valence electrons and have analogous valence electron configurations: these columns are called groups. The single exception is helium, which has two valence electrons like beryllium and magnesium, but is typically placed in the column of neon and argon to emphasise that its outer shell is full.

  7. Periodic table (electron configurations) - Wikipedia

    en.wikipedia.org/wiki/Periodic_table_(electron...

    Configurations of elements 109 and above are not available. Predictions from reliable sources have been used for these elements. Grayed out electron numbers indicate subshells filled to their maximum. Bracketed noble gas symbols on the left represent inner configurations that are the same in each period. Written out, these are: He, 2, helium : 1s 2

  8. Electron configuration - Wikipedia

    en.wikipedia.org/wiki/Electron_configuration

    Electron atomic and molecular orbitals A Bohr diagram of lithium. 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]

  9. Group 2 organometallic chemistry - Wikipedia

    en.wikipedia.org/wiki/Group_2_organometallic...

    Magnesium-containing compounds of this configuration are known as the Grignard reagents, though some calcium Grignard's are known and more reactive and sensitive to decomposition. Calcium grignard's must be pre-activated prior to synthesis. [6] There are three key reaction pathways for dialkyl and diaryl group 2 metal compounds. metathesis: