WORKSHEET ON CHEMICAL BONDING 9 th
grade
Valence electrons: When an atom undergoes a chemical reaction, only the outermost electrons
are involved. These electrons are of the highest energy and are furthest away from the nucleus.
These are the valence electrons. For the main group elements, the valence electrons are in the
orbitals s (this orbital holds up to 2 electrons) and p (this orbital holds up to 8 electrons).
IONIC BONDING
Ions are formed where electrons are transferred from the valence shell of one atom (usually a
metal) to the valence shell of another atom (non-metal) so that both end up with Noble Gas
configurations. Assume, in the first instance, that compounds between reactive metals and
reactive non-metals will be ionic.
1) Draw diagrams (outer electrons only) to show the bonding in the following covalent molecules.
Draw a before and after bond picture for each on another sheet of paper (your drawings
should be similar to the example above):
a) Lithium fluoride – LiF
b) Magnesium sulphide – MgS
c) Calcium chloride – CaCl2
d) Sodium oxide – Na2O
e) Aluminum oxide – Al2O3
Valence
electrons
