What forces typically hold nonmetal atoms together within a molecule?
Typically this force is a covalent bond, a region of high electron density between 2 positively charged nuclei such that internuclear repulsion is negated, and a net attractive force results.
Chemists routinely speak of intermolecular forces, the forces BETWEEN molecules, and intramolecular forces, the forces within molecules, which typically are covalent bonds.
Intermolecular forces may consist of H-bonding, dipole-dipole, or dispersion forces. You must remember to distinguish these, the forces BETWEEN molecules, and the (stronger) attractive forces between atoms within molecules.