An intramolecular force is a force acting within a molecule, such as a covalent bond, which holds the atoms of that molecule together. These forces are much stronger than the intermolecular forces acting between molecules. It is intramolecular forces that are broken in a chemical reaction, whereas intermolecular forces are overcome in melting and boiling.

分子内作用力是作用于分子内部的力,如共价键,它把该分子的各原子结合在一起。这类作用力比分子之间的分子间作用力强得多。化学反应中断裂的是分子内作用力,而熔化和沸腾中克服的则是分子间作用力。