In terms of electrons, describe the difference between the formation of the covalent bond in Cl2 and the ionic?

In Cl2, the two atoms are equally sharing one pair of electrons (one electron from each atom). In NaCl, the chlorine atom has an extra electron that it took completely away from a sodium atom. So, in NaCl, you have two particles, the sodium ion (Na+) and the chloride ion (Cl-). These two attract each other because of their opposite charges.