1. Covalent Bonding Where atoms learn to share

2. What do you already know? 1.THINK: On your own, write down what you know about covalent bonding. 2.PAIR: Quietly discuss you response with the person next to you. 3.SHARE: Combine your answers with the rest of the class

3. Summary Between non-metal atoms Atoms share electrons so that they each have a full outer shell Bonds can be: – Single (sharing 2 electrons) –Double (sharing 4 electrons) –Triple (sharing 6 electrons)

4. Types of Covalent Bonding Molecular Substances e.g. Carbon dioxide Network Lattices e.g. Diamond Layer Lattices e.g. Graphite

5. Molecular Substances Small covalent molecules – Each molecule only involves a few atoms Most exist as liquids or gases at room temperature Most have low melting and boiling temperatures WHY?...........

6. Therefore when melted the molecules separate from each other but the atoms within the molecules stay bonded together. Only weak forces of attraction BETWEEN the molecules, which are easy to overcome Strong forces of attraction WITHIN the molecules

7. Single Covalent Bonds: Chlorine Both chlorine atoms have 7 valence electrons and need 1 more to fill their valence shell. They form a single bond  both atoms complete their valence shells. The chlorine atoms are held together by electrostatic attraction between their nuclei and the shared pair of electrons Chlorine has a covalency (no of shared electrons) of 1 Diagrams don’t include inner shell electrons as these are not involved in bonding

8. Single Covalent Bonds: Hydrochloric Acid Using hydrogen as an example complete the following for Hydrochloric Acid: Identify how many valence electrons hydrogen and chlorine have and how many they require to fill their valence shell Draw a diagram of the covalent bond between hydrogen and chloride labelling the bonding and non-bonding electrons Determine the valency of each of the atoms.

9. Single Covalent Bonds: Molecules with more than 2 atoms Water (H2O) How many electrons does H need to complete it’s valence shell? How many electrons does O need to complete it’s valence shell? Draw a diagram of how you think two hydrogens and one oxygen can bond to form water.

10. Double Covalent Bonds Draw the electron configuration for Oxygen. What is it’s valency? How many valence electrons does it want to share then? What sort of bond will this be? (single/double/triple?) Draw a diagram of the covalent bond in O 2

11. Triple Covalent Bonds Draw the electron configuration for Nitrogen. What is it’s valency? How many valence electrons does it want to share then? What sort of bond will this be? (single/double/triple?) Draw a diagram of the covalent bond in N 2

12. Covalent Network Lattices Each atom is covalently bonded to four other atoms  forms strong covalent bonds throughout the lattice. Therefore: Solids at room temperature Incredibly high melting temperatures Examples: Diamond & Silica (Silicon Dioxide SiO 2 )

13. Covalent Layer Lattices Layered structure: Carbon atoms WITHIN the layers are held together by strong covalent bonds. –Each carbon atom is bonded to 3 other carbons –The 4 th electron from each carbon is delocalised and free to move within the layer Forces BETWEEN the layers are weak Therefore: Can conduct electricity (free electrons carry current) Examples: Graphite

14. Apply what you’ve learnt… Workbook: p64 part 1 p66 Textbook: p131 Q16 & 17 P133 Q31-34

15. Add in electrical conductivity of each type of covalent bonding