Double covalent bond
The bond formed between two atoms due to the sharing of two electron-pairs is called a double covalent bond or simply a double bond. It is denoted by two small horizontal lines (=) drawn between the two atoms, e.g., O = O, O = C = O etc.
Triple covalent bond
Bond formed due to the sharing of three electron pairs is called a triple covalent bond or simply a triple bond. Three small horizontal lines between the two atoms denote a triple bond e.g., N
N, and H-C
C-H (acetylene).
