2.1 Periodicity

Question 1

What are the trends in electrical conductivity in Period 3?

Answer 1

Increase Na to Al
Decrease Al to Ar
Al> Mg> Na as metallically bonded with increased delocalised electrons
Si is a semiconductor
P,S,Cl,Ar have no delocalised electrons

Question 2

What are the trends in atomic radii in Period 3?

Answer 2

Decreases as protons increase
outer electrons in same shell
Stronger pull due to more protons pulling the electrons closer to the nucleus

Question 3

What are the trends in electronegativity in Period 3?

Answer 3

Increases as protons increase
smaller atoms
stronger attraction from nucleus to 2 electrons in a covalent bond

Question 4

What are the trends in melting and boiling points in Period 3?

Answer 4

Decreases
Na, Mg, Al- stronger metallic bonds
Si, Giant covalent
P,S,Cl- simple molecular with weak van de waals
Ar- monoatomic

Question 5

What are the trends in ionisation energy in Period 3?

Answer 5

Increases as protons increase
smaller atoms
stronger attraction from nucleus to outer electrons.