Which force is mainly responsible for the binding of atoms into molecules?

Chemical bonding is caused by the electromagnetic attraction between negatively charged electrons and positively charged nuclei. Covalent, ionic and metallic bonds all arise from this same fundamental force, though quantum mechanics determines the detailed structure. Because of electromagnetism, atoms can join into molecules, solids and biological structures. This means the force underlies chemistry, materials science and life itself. In everyday matter, electromagnetic interactions are much more visible than gravity at the atomic scale.