The ''formula mass'' of any compound (ionic or molecular) is equal to the sum of the [[atomic mass]]es of its constituent elements. If the compound is molecular, then the terms ''molecular mass'' or ''molar mass'' may properly describe this quantity. | The ''formula mass'' of any compound (ionic or molecular) is equal to the sum of the [[atomic mass]]es of its constituent elements. If the compound is molecular, then the terms ''molecular mass'' or ''molar mass'' may properly describe this quantity. |