A mole is defined as the amount of substance that contains the same number of elementary entities as the number of atoms in 12 grams of carbon. Atoms, molecules, and other particles are some elementary entities that can be represented in moles. The number of molecules or atoms in a mole is known as Avogadro's number. The molar mass of any compound is defined as the mass of 1 mole of that compound, and is represented in grams per mole. The kinetic molecular theory of gases is a model based on several assumptions, which explains the physical characteristics of gases at the molecular level. The gas molecules in the container obey Newton's law and are in continuous motion, which is random and isotropic. The gas molecules behave as point particles, as the overall volume occupied by gas molecules is small in comparison to the total volume of the container. The collision of gas particles with each other and with the walls of the container are elastic and thus result in no net energy loss.