5.3 Formation of Covalent Bonds

Covalent bonds
■ Covalent bonds

	►	Chemical bond formed through the sharing of electrons between two non-metal atoms.
	►	During the formation of covalent molecules, each non-metal atom provides one or more electrons to be shared with other atom.
	►	Through the electron sharing, each non-metals will achieve duplet or octet electron arrangement.

■ Types of covalent bonds

	►	The types of covalent bond formed depends on the number of pairs of electron shared between two atoms.
	►	There are three types of covalent bond as shown in the table below. Number of pairs of electron shared between two atoms Type of covalent bond Example of molecule 1 Single covalent bond Hydrogen molecule, H2 ( H - H ) 2 Double covalent bond Oxygen molecule, O2 (O = O) 3 Triple covalent bond Nitrogen molecule, N2 (N ≡ N) A covalent bond can be represented by a straight line between the atom.

Formation of single covalent bond
■ Single covalent bond

	►	Sharing of a pair of electrons between two non-metal atoms.
	►	Each non-metal atom contributes one electron for sharing to achieve a stable electron arrangement.
	►	Example : hydrogen, H2; chlorine, Cl2; hydrogen chloride, HCl2; water, H2O; methane, CH4; ammonia, NH3; tetrachloromethane, CCl4

■ Formation of single covalent bond

►

The animation below shows the formation of single covalent bond.

■ This video contains information on the formation of single covalent bond.

Formation of double covalent bond
■ Double covalent bond

	►	Sharing of two pair of electrons between two non-metal atoms.
	►	Each non-metal atom contributes two electron for sharing to achieve a stable electron arrangement.
	►	Example : oxygen, O2; carbon dioxide, CO2

■ Formation of double covalent bond

►

The animation below shows the formation of double covalent bond.

Formation of triple covalent bond
■ Triple covalent bond

	►	Sharing of three pair of electrons between two non-metal atoms.
	►	Each non-metal atom contributes three electron for sharing to achieve a stable electron arrangement.
	►	Example : nitrogen, N2

■ Formation of triple covalent bond

►

The animation below shows the formation of triple covalent bond in nitrogen molecule, N2.

■ This video contains information on the formation of double and triple covalent bond.

Determining the formulae of covalent compound
■ Formulae of covalent compounds.

►

Covalent compounds comprise element from group 14, 15, 16, and 17. (non-metal).

■ Determining the formulae of covalent compounds.

	►	A non-metal element M need x electrons to achieve stable electron arrangement.
	►	A non-metal element N need y electrons to achieve stable electron arrangement.

►

Thus, the formula of the covalent compound formed will be MyNx

■ Number of electron to achieve stable electron arrangement

Group Number of electron needed to achieve stable electron arrangement Group 14 4 Group 15 3 Group 16 2 Group 17 1

■ Predicting the formula of a covalent compound.

	►	Determine the number of electron needed to achieve stable electron arrangement.
	►	Cross over the numbers of electron needed to achieve stable electron arrangement.
	►	The animation below shows the way of predicting the formula of covalent compound.

← 5.2 Formation of Ionic Bonds

5.4 Properties of Ionic and Covalent Compounds→

⇲ For exercise(objective and subjective), download for free on Android OS.