Sharing electrons occurs when atoms have a covalent bond. Covalent bonds occur between non-metals and there are two types of covalent bonds: Polar and Nonpolar Covalent bonds. Polar covalent bonds are when there is an unequal sharing of electrons which causes the atom that occupies the electron(s) more to have a slightly negative charge while the atom that occupies the electron(s) less has a slightly positive charge. Nonpolar covalent bonds basically have equal sharing of the electron(s).
Atoms bond because they need to become stable like the noble gases.
