Using only the elements Ca, Cl, and Si, give formulas for the following. (a) An ionic compound

Ionic compounds are formed when atoms transfer electrons, resulting in the formation of charged ions. Typically, a metal atom donates electrons to become a positively charged cation, while a non-metal atom accepts electrons to become a negatively charged anion. The electrostatic attraction between these oppositely charged ions leads to the formation of a stable ionic compound.

Valency refers to the ability of an atom to bond with other atoms, determined by the number of electrons in its outer shell. For example, calcium (Ca) has a valency of +2 as it can lose two electrons, chlorine (Cl) has a valency of -1 as it can gain one electron, and silicon (Si) typically has a valency of +4 or -4 depending on its bonding context. Understanding valency is crucial for predicting the formulas of compounds.

A chemical formula represents the composition of a compound using symbols for the elements and numerical subscripts to indicate the number of atoms of each element. In ionic compounds, the formula reflects the ratio of cations to anions that results in a neutral charge. For example, in calcium chloride (CaCl2), one calcium ion pairs with two chloride ions to balance the overall charge.