Summary
Highlights
Most atoms, excluding hydrogen, aim to have eight electrons in their outer shell to achieve chemical stability, a concept known as the Octet Rule. Atoms combine by giving up, accepting, or sharing electrons to complete their outer shells.
A covalent bond forms when atoms share electrons to satisfy the Octet Rule. For example, a carbon atom, needing four more electrons, can share with other atoms like four hydrogen atoms to achieve a stable outer shell with eight electrons. Hydrogen atoms, in this compound, achieve the stable configuration of two electrons in their first shell.
An ionic bond forms from the attraction between oppositely charged atoms, known as ions. This is demonstrated by the reaction between sodium and chlorine. Sodium, with one electron in its outer shell, tends to lose it, becoming positively charged. Chlorine, with seven outer electrons, tends to gain an electron, becoming negatively charged. These oppositely charged ions attract each other to form an ionic bond, such as in sodium chloride (table salt).