1. Covalent and Metallic Bonds

2. Covalent bonds
Recall that ionic bonds are when electrons are transferred (give and take) between atoms
Covalent bonds are formed when atoms SHARE electrons.
Carbon has four valence electrons, which does not make it ideal to become an ion (give or lose it’s electrons) because it takes too much energy. So instead it shares!

4. Covalent compounds
Elements on the periodic table that are close together are more likely to share electrons to form covalent bonds
Covalent compounds are especially important in living organisms
DNA
Proteins
Sugars
Organic compounds – containing carbon atoms

5. Properties of Covalent Compounds
Can be solids, liquids or gases at room temperature
Lower melting and boiling points than ionic compounds
Do not separate in water, nor does their solution conduct electricity

6. Bonds Single bond – one shared pair of electrons
Double bond – two shared pairs of electron
Stronger than single bonds
Triple bond- three shared pairs of electrons
Stronger than double and single bonds
Acetylene (gas used by welders) is an example
Nitrogen molecule (N2)

7. Metallic Bonds
Metallic bond is a bond formed when many metal atoms share their pooled electrons
Can bond to the same metal atoms or different ones
Electrons are not transferred, they move freely throughout the piece of metal
Electrons are not attracted to any particular atom
Properties:
good conductors of heat and electricity
Malleable
Ductile

9. Forming solids - crystals
A crystal is a regular, repeating arrangement of atoms, ions or molecules
Visualizing pg234

10. Forming solids - polymers
Polymers is a covalent compound made up of many small, repeating units linked together in a chain.
EXAMPLES: plastics, synthetic fibers, many paints, synthetic elastic compounds