1. Periodicity of Melting Points…
Assign the bonding and structure across period 3

2. Giant Metallic Lattice
Periodicity of Melting Points…
Metallic Bonding
Giant Metallic Lattice

3. Giant Covalent Lattice
Periodicity of Melting Points…
Covalent Bonding
Giant Covalent Lattice

4. Periodicity of Melting Points…
Covalent Bonding
Simple Molecular

5. Periodicity of Melting Points…
Based on the type of structure predict (and justify) which element has the:
Highest melting point
Lowest melting point

6. Periodicity of Melting Points… Highest = Silicon
Strongest bonds therefore requires the most energy to break them
Lowest = Argon
Single atoms mean no bonds that can have a dipole induced. Lowest IM forces, so least energy required.

7. Periodicity of Melting Points…
We are going to look at the trend in the melting points of period 2.
From the data, produce a relevant graph (this is going to be assessed)
Lithium
Beryllium
Boron
Carbon
Nitrogen
Oxygen
Fluorine
Neon
Melting Point /oC
180
1280
2027
3700
-210
-219
-187
-248.6

8. Periodicity of Melting Points…
Why is there a steep decrease in melting point between carbon and nitrogen? (4)
Why do Group two metals have a higher melting point than Group one? (3)

9. Periodicity of Melting Points…
Why is there a steep decrease in melting point between carbon and nitrogen? (4)
Both compounds have covalent bonds
Carbon is a giant covalent lattice
Nitrogen is a simple molecule with INTERMOLECULAR forces
Covalent bonds require more thermal energy to break than intermolecular forces

10. Periodicity of Melting Points…
Why do Group two metals have a higher melting point than Group one? (3)
Metallic bonding is the electrostatic attraction between the positive ions and the delocalised electrons
Group 2 metals have a 2+ charge AND group 1 metals have a 1+ charge
The stronger electrostatic attraction between 2+ and an electron requires more energy to overcome

11. Periodicity of Melting Points…
Using a mark scheme correctly is a skill. It allows you to gauge the level you are currently working at.
Unfortunately most students don’t use them properly.
Mark the example question using the mark scheme.