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.

intermolecular forces are the forces between molecules or particles.

there are two kinds of van der waals forces: weak london dispersion forces and stronger dipole-dipole forces.

in molecule of water there are dipole-dipole forces between negatively charged oxygen from one molecule of water and positively charger hydrogen of another molecule of water.

hydrogen bond is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (h), covalently bound to a highly electronegative atom such as flourine (f), oxygen (o) and nitrogen (n) atoms.