Chemical Bonding Forming Bonds Atoms can bond to each other and make molecules. These bonds are what hold molecules together. Bonds form when atoms either give away or share electrons. Covalent Bonds Covalent bonds are bonds in which atoms share electrons. Ionic Bonds Ionic bonds form when one atom takes an electron from another atom. Stable atoms are atoms that have full valence shells. Unstable atoms are atoms that do not have filled valence shells Metallic Bonds Metallic bonds occur when metal atoms share electrons. Electrons in the outer shells float together loosely and form a “sea” electrons.