First 235 words of the document:
A covalent bond is a strong bond between two non-metal atoms. It
consists of a shared pair of electrons. A covalent bond can be
represented by a straight line or dot-and-cross diagram.
Hydrogen and chlorine can each form one covalent bond, oxygen two
bonds, nitrogen three, while carbon can form four bonds
A covalent bond forms when two non-metal atoms share a pair of electrons.
The electrons involved are in the highest occupied energy levels - or outer shells
- of the atoms. An atom that shares one or more of its electrons will complete
its highest occupied energy level.
Covalent bonds are strong - a lot of energy is needed to break them.
Substances with covalent bonds often form molecules with low melting and
boiling points, such as hydrogen and water.
Example - the animation shows a covalent bond being formed between a
hydrogen atom and a chlorine atom, to form hydrogen chloride.
After bonding, the chlorine atom is now in contact with eight electrons in its
highest energy level - so it is stable. The hydrogen atom is now in contact with
two electrons in its highest energy level - so the hydrogen is also stable.
Hydrogen forms one covalent bond. The noble gases in Group 0 do not form