How many electrons do most atoms seek to have on their valence shell? Using this information, explain why certain elements are unreactive and why other elements are reactive.

2n² are the electrons in the valence shell. Based on this outer shell of gaining or losing electrons stable electronic configuration is determined and reactive and unreactive elements are determined.

Explanation:

The electrons in the outermost occupied shell (or shells) determine the chemical properties of the atom it is called the valence shell.Valence electrons are of crucial importance because they lend deep insight into an element’s chemical properties, whether it is electro-negative or electro-positive in nature, or they indicate the bond order of a chemical compound  the number of bonds that can be formed between two atoms.

The electrons in the valence shell most seeked by the atoms are 2n².

The Noble Gases are unreactive due to the fact that they have full outer shells, and therefore do not need to gain or lose electrons in order to reach a stable electronic configuration. The reactive elements are reactive due to the fact that they readily lose or gain electrons from their outer shell in order to reach a stable electronic configuration.