What is the trend in first ionisation energy across a period?

Overall, the general trend is an increase across the period.

The decrease in shielding (as outer electrons are less influenced by the nucleus) is outweighed by an increased nuclear charge and a decreased atomic radius.

However, the value actually decreases between group 2 and 3. This is a result of the electronic configurations of these elements. The outermost electron in Be (in a 2s orbital) is less easily removed than that of B (in a 2p orbital). The same occurs from group 5 and 6.

BW
Answered by Ben W. Chemistry tutor

12695 Views

See similar Chemistry GCSE tutors

Related Chemistry GCSE answers

All answers ▸

What are the features of a diamond allotrope?


Why is Copper used in cooking equipment and wiring?


solid magnesium cannot flow, but liquid magnesium can. Explain why. (3)


What are the keypoints involved in ionic bonding?


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