What is formula unit?

A formula unit is the smallest whole number ratio of atoms in a compound. It represents the chemical formula of an ionic compound, which consists of positively and negatively charged ions arranged in a specific ratio to achieve electrical neutrality.

For example, the formula unit of sodium chloride (table salt) is NaCl, which represents one sodium ion (Na+) and one chloride ion (Cl-) combined in a 1:1 ratio.

Formula units are used to represent the simplest ratio of elements in a compound and are essential in understanding the composition and properties of chemical compounds. They are different from molecular formulas, which represent the actual number of atoms in a molecule.