Question

Using each of the following electron arrangements, give the formulas for the cation and anion that form, the formula for the compound they form, and its name.

Short answer

The complete table is :-

Electron Arrangements		Cation	Anion	Formula of Compound	Name of Compound
$2,8,2$	$2,5$	data-custom-editor="chemistry" ${\mathrm{Mg}}^{2+}$	data-custom-editor="chemistry" ${\mathrm{N}}^{3-}$	data-custom-editor="chemistry" ${\mathrm{Mg}}_3{\mathrm{N}}_2$	Magnesium nitride
$2,8,8,1$	$2,6$	data-custom-editor="chemistry" ${\mathrm{K}}^{+}$	data-custom-editor="chemistry" ${\mathrm{O}}^{2-}$	data-custom-editor="chemistry" ${\mathrm{K}}_2\mathrm{O}$	Potassium oxide
$2,8,3$	$2,8,7$	data-custom-editor="chemistry" ${\mathrm{Al}}^{3+}$	data-custom-editor="chemistry" ${\mathrm{Cl}}^{-}$	data-custom-editor="chemistry" ${\mathrm{AlCl}}_3$	Aluminium chloride

Step-by-step solution

Given information  

We have been given the electron arrangements.

We need to find the formulas for the cation and anion that form, the formula for the compound they form, and its name.

Explanation 

When an atom gives away electron, it forms a cation and when it takes up electron, it forms an anion.

The complete table is :-

Electron Arrangements		Cation	Anion	Formula of compound	Name of compound
$2,8,2$	$2,5$	data-custom-editor="chemistry" ${\mathrm{Mg}}^{2+}$	data-custom-editor="chemistry" ${\mathrm{N}}^{3-}$	data-custom-editor="chemistry" ${\mathrm{Mg}}_3{\mathrm{N}}_2$	Magnesium nitride
$2,8,8,1$	$2,6$	data-custom-editor="chemistry" ${\mathrm{K}}^{+}$	data-custom-editor="chemistry" ${\mathrm{O}}^{2-}$	data-custom-editor="chemistry" ${\mathrm{K}}_2\mathrm{O}$	Potassium oxide
$2,8,3$	$2,8,7$	data-custom-editor="chemistry" ${\mathrm{Al}}^{3+}$	data-custom-editor="chemistry" ${\mathrm{Cl}}^{-}$	data-custom-editor="chemistry" ${\mathrm{AlCl}}_3$	Aluminium chloride