3.2.1 Periodicity

Question 1

How are elements according to their position in the Periodic Table?

Answer 1

An element is classified as s, p, d or f block according to its position in the Periodic Table, which is determined by its proton number.

Question 2

What is the trend in atomic radius of the elements Na-Ar?

Answer 2

Atomic radius decreases across the period,

nuclear charge increases

electrons enter the same energy level and experience similar shielding
attraction between the nucleus and outer electrons becomes stronger

pulls the electrons in closer to the nucleus

Question 3

The trend in first ionisation energy of the elements Na-Ar

Answer 3

Same as atomic radius explanation with :
First ionisation energy increases across the period -more energy is required to remove an electron

Question 4

The trend in melting point of the elements Na-Ar

Answer 4

The melting points metals increase from sodium to aluminium
- strength of metallic bonding.

Silicon - much higher melting point with its giant structure.

The melting points non-metals - sizes of the van der Waals forces between molecules- sizes of the molecules