Periodicity [3]

Question 1

Define Periodicity

Answer 1

Periodicity is the concept that elements have predictable trends in their physical and chemical properties based on their group, period, block, atomic number etc.

Question 2

Define “First Ionisation Energy”

Answer 2

An element’s first ionisation energy is the energy it takes to remove one mole of electrons from one mole of an element’s gaseous atoms under standard state conditions (298K and 101KPa)

Question 3

Notate the first and second ionisation energies of sodium

Answer 3

Na(s) ➞ e⁻ + Na⁺(g)
Na⁺(g) ➞ e⁻ + Na²⁺(g)

Question 4

FIE drop between group 2 (Be) and group 3 (B)

Answer 4

The reason is that shielding from the s-subshell and an increase in atomic radius outweighs the nuclear charge increase, resulting in less nuclear attraction on the valence electron.

This makes it easier to overcome the attraction and remove the electron.

Question 5

FIE drop between group 5 (N) and group 6 (O)

Answer 5

The reason is that the O’s valence electron is experiencing repulsion from the other electrons in the p-orbital. This decreases the nuclear attraction it experiences, making it’s removal easier.

Question 6

Why does FIE decrease down a group?

Answer 6

This is because shielding and atomic radius increase. There are more electrons on lower subshells between the valence electron and the nucleus as well as a greater distance. This decreases nuclear attraction to an extent of outweighing any increase in nuclear charge.