Atoms use electrons to form bonds and make compounds.
Atoms combine in order to hae complete outer electron shells, as this is most energetically stable.
Ionic bonds: elements with 1/2 outer shell electrons react with elements with 1/2 gaps in the outer electron shell, the electrons are moved from one atom to the other.
This results in the atom with lost electrons becoming a positively charger ion, and the atom which gained electrons becomes a negatively charged ion.
Ionic compounds: the oppositely charged ions of ionic compounds are held together by the electrical attraction.
Ionic compounds can conduct electricitiy, and are usually soluble in water. (water has charged particles too, it is a polar solvent)
Covalent bonds: when these form the electrons are shared between the two atoms, this generally produces compounds with particles which don't have a strong electrical charge.