1. COVALENT BONDING
-formed from the sharing of pairs of electrons between atoms of non-metallic elements
- Sharing of electrons occurred to satisfy the octet requirements of the atoms

2. In covalent bonds, electrons are shared between electronegative elements.

3. Carbon-carbon covalent bonding

4. PROPERTIES OF COVALENT COMPOUNDS
LOW MELTING POINT – few substances have melting points which exceeds 300oC.
At room temperature, covalent compounds can exist as a solid, liquid or gas.
Indicates weak attractive force between the molecules

5. SOFT SOLIDS – covalent compound solids are soft at room temperature
ELECTRICAL CONDUCTIVITY – whether solid, liquid or gas, covalent compounds are non-conductors of electricity

6. MOLECULAR COVALENT ELEMENTS
DIATOMIC MOLECULES –
Fluorine – F2 Chlorine – Cl2
Bromine – Br2 Iodine – I2
Hydrogen – H2 Oxygen – O2
Nitrogen – N2
OTHERS –
Phosphorus – P Sulfur – S8

7. NOBLE GASES – exists as neutral atoms NOT molecules
He, Ne, Ar, Kr, Xe and Rn atoms

8. STEPS IN DRAWING LEWIS DOT STRUCTURE OF COVALENT COMPOUNDS
Draw the Lewis dot structure of H2O.
1. Determine the central atom – The central atom requires the greatest number of electrons. The other atoms are called the side atoms.
Number of valence e-
Number of e- needed to satisfy the octet H 1 O 6 2
Side atom
Central atom

9. 2. Place the central atom in the middle and surround it with the side atoms.

10. 3. Determine the total number of valence electrons needed to satisfy the octet.
2 H atoms x 2 e- / H atoms = e-
1 O atom x 8 e- / O atom = e-
e- needed for octet e-

11. EXCEPTIONS TO OCTET RULE
ELEMENT
VALENCE e- REQUIREMENT
HYDROGEN 2
BORON 6
PHOSPHORUS 10

12. 4. Determine the total number of valence atoms available.
2 H atoms x 1 e- / H atoms = 2 e-
1 O atoms x 6 e- / O atom = 6 e-
e- available e-

13. 5. Subtract the total number of valence electrons available from the total number of valence electrons needed to determine the number of electrons that must be shared.
e- needed for octet = e-
e- available = e-
e- that must be shared e-

14. 6. Place the number of shared e- around the central atom
6. Place the number of shared e- around the central atom. Distribute the remaining electrons. H O H X X