Periodic properties

Question 1

What is periodicity?

Answer 1

Periodicity is a reapeating pattern across different periods of the periodic table

Question 2

Physical properties of period 2 - melting/boiling points

Answer 2

From Li –> Be, bonding is metallic
* m.pt/b.pt increase because metallic bonding gets stronger as charge on cation increases

B –> C have giant covalent lattices
* Require a lot of energy to overcome

From N –> Ne, simple molecules
* Weak london forces that don’t require much energy to overcome

Question 3

Physical properties of period 2 - ionisation energies

Answer 3

Ionisation energy increases
* Shielding is relatively constant due electrons occupying the same shell
* Number of protons increase, so outer electrons are held closer
* Stronger attraction between nucleus and outer electron means high energy required to remove it

Question 4

Physical properties of period 3 - melting/boiling points

Answer 4

From Na –> Al, metallic bonding
* Metallic bonding gets stronger with increased proton number

Si has a giant covalent structure, which is macromolecular
* many strong covalent bonds require a lot of energy to overcome

P –> Cl are simple molecules
* The london forces do not require much energy to overcome
* Of these, sulphur has the strongest London forces due to having the most electrons

Ar - Noble gas that exists as a monoatomic element
* Consists of very weak London forces
* Very small amount of energy is required to break them

Question 5

Physical properties of period 3 - ionisation energies

Answer 5

Ionisation energy increases
* Shielding is relatively constant due electrons occupying the same shell
* Number of protons increase, so outer electrons are held closer
* Stronger attraction between nucleus and outer electron means high energy required to remove it