Covalent bonding

• Physics
• Secondary Education
• Age 13

Sound

Covalent bonding

October 08, 2025

We are learning to:
a) know what is meant by the term "covalent bond".

b) be able to draw a diagram that shows the formation of covalent bonds in simple molecules.

c) understand why diamond is used in cutting tools and graphite as a lubricant, as well as in pencils. 

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Sound

Recall

compounds

Ionic compounds

Covalent compounds

sodium chloride

carbon monoxide

silver chloride

sugar

oxygen gas

proteins

ammonia

sodium hydrogen carbonate

hydrogen

Any questions?

Sound

Theory

Understanding covalent compounds

We are learning to:
a) know what is meant by the term "covalent bond".

b) be able to draw a diagram that shows the formation of covalent bonds in simple molecules.

c) understand why diamond is used in cutting tools and graphite as a lubricant, as well as in pencils. 

Molecule of Chlorine gas

Non-metal atoms form bonds with other non-metal atoms by sharing pairs of electrons – this is called _____________ bonding.

1. ionic
2. metallic
3. covalent

Sharing of electrons in one molecule of hydrogen

Each non-metal atom forms as many bonds as it can (to become more stable) until the outer shell is _____.

1. with 8 e-
2. full
3. completely filled
4. A or C

Drawing a dot-and-cross diagram for covalent bonds

Hydrogen atoms have a valency of 1, so each can share one electron to form one bond.

The ___________ of electrons, one from each atom, is a covalent bond.

1. transfer
2. shared pair
3. movement

The negatively charged electrons of the shared pair attract the positively charged nuclei of the two atoms, holding them together strongly through __________.

1. electrostatic attraction
2. magnetic force
3. electromagnetic force

Electrostatic attraction between the shared pair of electrons and the atomic nuclei

What keeps the two atoms together?

An oxygen atom has a valency of 2, so it shares two of its electrons to form ________ covalent bonds.

1. 1
2. 2
3. 3
4. 0

How will you show the covalent bonds in a water molecule?

Any questions?

Practice!

CHOOSE TWO.

Draw dot and cross diagrams for these molecules: 

• Hydrogen chloride HCl
• Chlorine Cl₂ 
• Methane CH₄
• Ammonia NH₃

Self-check

Hydrogen chloride HCl

Chlorine Cl₂ 

Methane CH₄

Ammonia NH₃

Any questions?

Sound

Today, we learned that:

• The shared pair of electrons, one from each atom, is a covalent bond.
• Covalent bonding happens when non-metal atoms form bonds with other non-metal atoms by sharing pairs of electrons.
• We draw the shared pair as one dot and one cross in the overlap between the two outer shells.
• The valency tells us how many electrons will be shared to form covalent bonds.