Electronic Configuration

This is a revision concept collection of past concepts.

Work In Progress

This page is a work-in-progress, and requires further review and contribution.

Valency

Valency is the combining power of an atom, also known as the number of electrons an atom of the element needs to lose or gain to bond/combine. (This is closely related with Ions and Bonding.)
- For example, $M g$ has two valence electrons, which means it has a valency of 2.
Valencies help to predict the formulae of ionic compounds using the ‘swap and drop’ method.
- For example, $[M g]^{2 +} + [O]^{2 -} \to M g O$ . $M g$ and $O$ have a 1:1 ratio and thus we drop the ionic number to the amount of atoms ( $M g_{2} + O_{2}$ ) and drop the amount ( $M g + O \to M g O$ ).
Elements in the same group (in the periodic table) have the same valency.
- For example, group 1 has a valency of 1, group 2 has a valency of 2, and etcetera.