The chemical formula for calcium chloride, CaCl₂,<span> hows that the compound contains two chlorine ions for every calcium ion. Ca is a group 2 element with 2 electrons in its outer shell. Cl is a group 7 element with 7 electrons in the outermost shell. When it forms an ionic compound, electrons are transferred from Ca to Cl. Ca gives out 2 electrons becomes Ca</span>²⁺ and Cl can take only one electron -Cl⁻<span> and become stable. Therefore 2 Cl atoms are needed to take in the 2 electrons and be stable. Therefore compound formed between 1 </span>Ca²⁺ ion and 2 Cl⁻ ions.
