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

12511 Views

See similar Chemistry GCSE tutors

Related Chemistry GCSE answers

All answers ▸

For the reaction, 2SO2(g) + O2(g) => 2SO3(g), suggest the optimal conditions to maximise yield of SO3 when the forward reaction is exothermic.


What is the test for CO2 gas? Describe the overall reaction that takes place in the instance of a positive result and write its reaction equation.


How is an ionic bond formed?


Calculate the number of moles in 0.2g of NaCl


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