Final answer:
The adjective 'empirical' when used with formula, represents the simplest whole number ratio of atoms in a compound, known as the empirical formula. It is used to show the lowest whole-number ratio of elements in a compound, which is distinct from the molecular formula.
Step-by-step explanation:
The adjective that, when used with formula, refers to the simplest whole number ratio of atoms in a compound is empirical. The empirical formula represents the simplest ratio of elements in a compound, providing the minimal whole-number ratio between the atoms of the elements that comprise the substance. Unlike the molecular formula, it does not reflect the exact number of atoms in a molecule but instead offers a simplified representation.
For instance, the molecular formula for glucose is C6H12O6, whereas its empirical formula is CH2O, which displays the elements' relative amounts by the smallest possible whole numbers. To determine the empirical formula from the molecular formula, one would simply divide the subscripts in the molecular formula by their greatest common divisor. Hence, for glucose, dividing each elemental count by 6 (the greatest common divisor for 6, 12, and 6) yields the empirical formula CH2O.
Analyzing compounds often involves finding their empirical formula first, which is a critical step in determining the actual molecular formula. It's important to recognize that an empirical formula alone cannot be converted into a molecular formula without additional information, such as the compound's molar mass.