The mass of a single rice grain is extremely large compared to the mass of a single atom. (a typical hydrogen atom has a mass of 1.66 × 10–24 g—too small to even imagine! ) chemists therefore count atoms in large groups, called moles, where one mole contains 6.02 × 1023 (avogadro’s number) of atoms. let’s define a food-mole as containing 602 particles (rice, beans, peas, etc.) calculate the mass of one food-mole of rice. this is the food-molar mass of rice.