In an ionic or covalent compound, the smallest whole number ratio of the elements is called the empirical formula. The empirical formula represents the simplest whole number ratio of the elements present in the compound, without specifying the actual number of atoms or molecules.

To determine the empirical formula, the chemical formula of the compound is simplified by dividing the subscripts of all elements by the greatest common factor. This process ensures that the ratio of the elements is reduced to its simplest form.

For example, consider the compound with the chemical formula C₆H₁₂O₆. To find the empirical formula, we divide all subscripts by the greatest common factor, which is 6:

C₆H₁₂O₆ ÷ 6 = CH₂O

Therefore, the empirical formula of the compound is CH₂O, which represents the smallest whole number ratio of the elements carbon (C), hydrogen (H), and oxygen (O).