1. Bonding & Polarity
SCH3U/4C
Ms Richardson

2. Ionic or Covalent?
Recall that bonding between atoms can be divided into three types:
Ionic
Electrons are transferred
Non-polar Covalent
Electrons are shared equally
Polar-covalent
Electrons are shared unequally, creating a partial charge
The type of bond can be determined by looking at the difference in electronegativities (∆ 𝐸 𝑁 ) between the two elements involved

3. Properties of Ionic Compounds
The different types of bonds in molecules cause them to have very different properties:
Very high melting points
Often solid crystal lattice at room temperature
Soluble in water, but not non-polar substances
Conducts electricity when in liquid state (but not solid)
Conducts electricity when in an aqueous solution (example: salt water)

4. Properties of Covalent Compounds
The force of attraction due to shared electrons is less than that of transferred electrons.
For this reason, covalent (molecular) compounds tend to differ in properties:
Gas, liquid or solid at room temperature
Low melting and boiling points
Poor electrical conductivity (in all states)
Soluble in nonpolar substances, but not water

5. Bonding & Polarity
When electrons are shared unevenly between two atoms, a partial charge (dipole) is formed on one end of the molecule.
This is known as a polar-covalent bond and can be identified by observing a ∆ 𝐸 𝑁 of

6. Molecules & Polarity
Some molecules with polar bonds form non-polar molecules.
This occurs due to their shape.
When a molecule has opposing, but equal dipoles, the dipoles cancel each other, resulting in a non-polar molecule