Explain the trend in 1st ionisation energy across the period 3 elements, explaining the anomalies of aluminium and sulfur.

The overall trend is that the 1st ionisation energy increases. This is because as the nuclear charge increases, the attraction of the nucleus to the surrounding electrons becomes stronger. This means that more energy is required to break this electrostatic attraction.Both sulfur and aluminium deviate from the trend and show lower 1st IEs than expected. For sulfur, it is the first element with an electron in the 3p orbital, and as such it lies slightly further from the nucleus and as such is easier to remove.For aluminium, it is the first element to put 2 electrons in one subshell (the first 2p). As such, there is slight repulsion between the two electrons and this weakens the electrostatic interaction with the nucleus, making it easier to remove.

JW
Answered by Jack W. Chemistry tutor

9941 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

Does Mg or Al have the higher first ionisation energy? Explain your answer.


Write a balanced equation for the reaction between NaOH and sulfuric acid. A conical flask contains 25cm^3 of 0.124M NaOH, a burette contains 0.0625M sulfuric acid. Find the minimum amount of acid required to completely react with the NaOH in the flask.


Calculating the charge of a molecule e.g In NH4 what is the charge of the nitrogen atom?


What is the rate of a reaction and how can you determine it experimentally?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning