2020 P1 Q2 - Deducing Group from Successive IE

Let's take a look at 2020 A Levels H2 Chemistry Paper 1 Question 2.

2020 p1 q2 question

We are required to determine the element that has the above-mentioned fifth to ninth ionisation energies.

The concept is to identify the most significant increase in ionisation energy that will correspond to a change in principal quantum shell.

Let's work out the difference in the ionisation energies.

2020 p1 q2 identify big jump in IE

The most significant jump is from 8th to 9th IE where the increase is 27,000 kJ mol-1.

This means that the 9th electron is much harder to remove than 8th electron, hence it must be from an inner filled principal quantum shell.

The 8th electron and all the electrons before that must be from valence shell.

So this element has 8 valence electrons and must be from Group 18.

2020 p1 q2 deduce group

We can now look at the options and see which element is in Group 18, a noble gas.

2020 p1 q2 answer

Therefore the answer to this question will be option D.

Topic: Atomic Structure, Physical Chemistry, A Level Chemistry, Singapore

Back to list of questions for 2020 A Level H2 Chemistry Paper 1.

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