1. Covalent Bonding & Intermolecular Forces

2. Key Knowledge Materials from molecules
representations of molecular substances (electron dot formulas, structural formulas, valence structures, ball and-stick models, space-filling models) including limitations of representations
shapes of molecules and an explanation of their polar or non-polar character with reference to the electronegativities of their atoms and electron-pair repulsion theory
explanation of properties of molecular substances (including low melting point and boiling point, softness, and non-conduction of electricity) with reference to their structure, intramolecular bonding and intermolecular forces
the relative strengths of bonds (covalent bonding, dispersion forces, dipole-dipole attraction and hydrogen bonding) and evidence and factors that determine bond strength including explanations for the floating of ice and expansion of water at higher temperatures.

4. Boardworks AS Chemistry Bonding and Intermolecular Forces
Covalent bonding

5. The Three Different Types Of Covalent Compounds
Covalent compounds can be formed when non-metals are chemically combined.
Each atom shares its electrons with others.  
Covalent substances can be separated into two major groups: 
1. Covalent molecular substances – consist of a small number of atoms to form small molecules such as carbon dioxide (CO2)
2. Covalent lattices – consist of an infinite number of atoms to form giant network lattices (diamond) and layer lattices (graphite).

6. Covalent Molecular Compound Properties
explanation of properties of molecular substances (including low melting point and boiling point, softness, and non-conduction of electricity) with reference to their structure, intramolecular bonding and intermolecular forces
Covalent Molecular Compound Properties
Can consist of elements only or compounds. 
In general, covalent molecular substances:
can be solids, liquids or gases at room temperature (weak intermolecular forces).
have low melting and boiling points (weak intermolecular forces).
are poor conductors of electricity and heat (no free moving charged particles).

7. How is the ratio of atoms calculated?
Boardworks GCSE Additional Science: Chemistry
Covalent Bonding
How is the ratio of atoms calculated?
To calculate the ratio of atoms in a stable covalent compound:
1. Work out how many electrons are needed by each
non-metal element to complete its outer electron shell.
2. Work out the ratio of atoms that will provide enough
shared electrons to fill all the outer shells.
For example, how many nitrogen and hydrogen atoms bond together in an ammonia molecule?
element N H
electron configuration
(2.5)
(1)
electrons needed 3 1
ratio of atoms 1 3

8. Covalent bonding in ammonia
Boardworks GCSE Additional Science: Chemistry
Covalent Bonding
Covalent bonding in ammonia
How do nitrogen and hydrogen atoms form covalent bonds in a molecule of ammonia?
element N H N
electron configuration
(2.5)
(1) H H
electrons needed 3 1
ratio of atoms H 1 3
NH3 or H N H H

9. Covalent bonding in methane
Boardworks GCSE Additional Science: Chemistry
Covalent Bonding
Covalent bonding in methane
How do carbon and hydrogen atoms form covalent bonds in a molecule of methane? H
element C H
electron configuration
(2.4)
(1) C H H
electrons needed 4 1
ratio of atoms 1 4 H
CH4 or H C H H

10. Single covalent bonds
Double covalent bonds
Triple covalent bonds

11. Covalent Molecular Element
Covalent Molecular Compound

12. Representing Covalent Bonds
representations of molecular substances (electron dot formulas, structural formulas, valence structures, ball and-stick models, space-filling models) including limitations of representations
Representing Covalent Bonds
Electron Dot Diagram/ Lewis Structure:
Dots represent valence electrons
Valence Formula:
All non-bonding (lone pair) electrons and bonding electrons are represented by a dash, these lone pair of electrons help to determine the shape of the molecule.
Structural Formula:
No lone pairs are included, only dashes representing the pair of bonding electrons. H F H F

13. Intramolecular and Intermolecular Attractions
Intermolecular attractions are attractions between one molecule and a neighbouring molecule.
Intramolecular attractions are the forces of attraction which hold an individual molecule together for example the covalent bonds.