Periodicity (Year 1)

Question 1

What are the 4 blocks of the periodic table?

Answer 1

s-block (group 1 + 2)
p-block (groups 3 - 0)
d-block (transition metals)
f-block (radioactive elements)

Question 2

Explain the trend in atomic radius across a period

Answer 2

Atomic radius decreases across the period
Increased nuclear charge for same number of electron shells
Outer electrons pulled closer to nucleus from nuclear charge
Therefore atomic radius is reduced

Question 3

Explain the trend in ionisation energy across a period

Answer 3

Ionisation energy increases across the period
Atomic radius decreases, hence nuclear charge increases
Outer electrons held more strongly so more energy required to remove outer electron and ionise atom

Question 4

What happens to the melting points between sodium and aluminium in period 3?

Answer 4

Melting points increase from sodium to aluminium
All metals with metallic bonding
More free electrons increases the electrostatic forces

Question 5

Why does the melting point increase dramatically from aluminium to silicon?

Answer 5

Silicon has a very strong covalent structure
More energy required to break strong covalent bonds

Question 6

Why does melting point decrease between phosphorus and chlorine?

Answer 6

P, S and Cl all have simple covalent molecules with weak Van der Waals forces
Less energy required to overcome these weak intermolecular forces

Question 7

Why does argon have the lowest melting point?

Answer 7

Argon has a full outer shell of electrons so is very stable
Weak Van der Waals
Even less energy required to overcome the weak VdW forces