For each missing word or phrase, circle the choice that correctly completes the sentence. When electrons transfer from one atom to another, both atoms become (ions / isotopes / molecules / electrons) and they are held together by a(n) (polar / covalent / molecular / ionic) bond. When electrons are shared between atoms, a(n) (ionic / covalent / hydrogen / point) bond forms between the atoms, and the joined atoms become a(n) (element / ionic compound / molecule / isotope).