The chemical formula for the compound magnesium perchlorate is Mg(ClO₄)₂
Magnesium perchlorate or Mg(ClO₄)₂ is an ionic compound.
Perchlorate here is an anion which is represented by ClO₄⁻. Perchlorate is a polyatiomic anion, where one Cl atom is bonded to four O atoms.
The magnesium cation is represented by Mg²⁺
So one Mg²⁺ cation combines with two ClO₄⁻ anion to form one molecule of Mg(ClO₄)₂