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  2. Valence electron - Wikipedia

    en.wikipedia.org/wiki/Valence_electron

    Similar to a core electron, a valence electron has the ability to absorb or release energy in the form of a photon. An energy gain can trigger the electron to move (jump) to an outer shell; this is known as atomic excitation. Or the electron can even break free from its associated atom's shell; this is ionization to form a positive ion. When an ...

  3. Alkaline earth metal - Wikipedia

    en.wikipedia.org/wiki/Alkaline_earth_metal

    Mg 2+ Disodium phosphate is a very selective reagent for magnesium ions and, in the presence of ammonium salts and ammonia, forms a white precipitate of ammonium magnesium phosphate. Mg 2+ + NH 3 + Na 2 HPO 4 → (NH 4)MgPO 4 + 2Na + Ca 2+ Ca 2+ forms a white precipitate with ammonium oxalate. Calcium oxalate is insoluble in water, but is ...

  4. Group 2 organometallic chemistry - Wikipedia

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

    Magnesium anthracenide with three thf ligands. [1] Group 2 organometallic chemistry refers to the organic derivativess of any group 2 element. It is a subtheme to main group organometallic chemistry. [2] [3] By far the most common group 2 organometallic compounds are the magnesium-containing Grignard reagents which are widely used in organic ...

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

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

    However there are numerous exceptions; for example the lightest exception is chromium, which would be predicted to have the configuration 1s 2 2s 2 2p 6 3s 2 3p 6 3d 4 4s 2, written as [Ar] 3d 4 4s 2, but whose actual configuration given in the table below is [Ar] 3d 5 4s 1.

  6. Group (periodic table) - Wikipedia

    en.wikipedia.org/wiki/Group_(periodic_table)

    In the periodic table of the elements, each column is a group. In chemistry, a group (also known as a family) [1] is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table; the 14 f-block columns, between groups 2 and 3, are not numbered.

  7. Extended periodic table - Wikipedia

    en.wikipedia.org/wiki/Extended_periodic_table

    This is an accepted version of this page This is the latest accepted revision, reviewed on 12 November 2024. Periodic table of the elements with eight or more periods Extended periodic table Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium ...

  8. 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.

  9. Transition metal - Wikipedia

    en.wikipedia.org/wiki/Transition_metal

    The s subshell in the valence shell is represented as the ns subshell, e.g. 4s. In the periodic table, the transition metals are present in ten groups (3 to 12). The elements in group 3 have an ns 2 (n − 1)d 1 configuration, except for lawrencium (Lr): its 7s 2 7p 1 configuration