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Atomic Structure

Valency, Oxidation State and Ionic Compounds.

When a metal reacts with a non-metal,
the metal will lose electrons to form a positive ion,
the non-metal will gain electrons to form a negative ion.
The compound which is formed will be ionic. It will form a giant structure.
If you do not know whether an element is a metal
 or a non-metal see the periodic table.

The valency (combining power) of a metal is the same
as its oxidation state (the charge on the ion).

The number of electrons which a metal will lose
is the same as its group number in the periodic table.
A metal in group 1 will form a 1+ ion. (Valency 1, oxidation state 1+).
A metal in group 2 will form a 2+ ion. (Valency 2, oxidation state 2+).

The number of electrons which a non-metal will gain
will be 8 minus its group number.
A non-metal in group 6 will form a 2- ion.  (Valency 2, oxidation state 2-).
A non-metal in group 7 will form a 1- ion.  (Valency 1, oxidation state 1-).
A non-metal ion is negative because it has gained electrons.

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Copyright © 2008 Dr. Colin France. All Rights Reserved.