A chemical bond is formed when there is a transfer or sharing of electrons. When there is a transfer, what we have is that the electrons completely leave the outermost shell of an atom, usually metal to the outermost shell of another atom, usually a nonmetal. This particularly alters the electronic configuration of these atoms. This is ionic or electrovalent bonding
Now, electron sharing is also another way of chemical bond formation. Electrons might be shared between two atoms in a case principally known as covalent bonding. The electrons here are controlled by the 2 nuclei
