A Level Chemistry 2017 Paper 1 Question 8 Solution - Exclusive

In this exclusive video we want to discuss the suggested solution for A Levels Chemistry (H2 Chemistry) 2017 Paper 1 Question 8.

Let's take a look at this question.

2017 A Level H2 Chemistry Paper 1 Qn8 Question

Topic tested is on Atomic Structure, in particular using ionisation energy trends to determine the Group an element is in.

When comparing first ionisation energies of consecutive elements, we look out for a large change in ionisation energy.

This big difference in ionisation energy corresponds to a change in principal quantum shell, as electrons in an electron shell with higher principal quantum number will be much farther away from the nucleus, so the attraction between the nucleus and electron will be much weaker, and much less energy is required to remove the electron.

By focusing on the big change in ionisation energy, we can deduce whether the electrons removed are from an inner shell or outer shell, and determine which Group that element is in.

This question is about fifth ionisation energies, but the concept is the same.

We just need to focus on the big jump in ionisation energy, figure out which element has a change in principal quantum shell, and add back the appropriate number of electrons lost from first ionisation to fourth ionisation to work out its Group.

For this question the biggest jump in ionisation energy is between R and S.

2017 A Level H2 Chemistry Paper 1 Qn8 big jump in ionisation energy

We can deduce the same conclusion from the perspective of R or S that Q has to be in Group 13.

Therefore the formula of chloride of Q has to be QCl3 and answer to this question is B.

Check out this video for the full discussion and suggested solution!

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

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