Why does the first ionisation energy generally increase across a period? Explain why there are dips in energy between groups 2 and 3 and groups 5 and 6?

1st ionisation energy increases across a period as nucleus gets more positive, no further increase in shielding due to electrons being added to same shell, atomic radius decreases, attraction between nucleus and highest energy electrons increases, so more energy is required to move the highest energy electron. Dip in energy between groups 2 and 3 due to highest energy election occupying a p orbital, which is slightly higher in energy than an s orbital.Dip between groups 5 and 6 due to extra electron being added to an already occupied p orbital, making one of the valence p orbitals full. This is a destabilising interaction due to increased repulsion between the electrons, meaning the highest energy electron in group 6 is more easily lost.

Answered by Chemistry tutor

5405 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

Why is the melting temperature of Magnesium higher than that of Sodium?


Explain how CH3CH2CHO can react with a Grignard reagent to produce CH3CH2CH(OH)CH2CH3. State the reagents and give the mechanism.


A compound is found to contain 30.7% Sulfur, 23,3% Magnesium and 46% Oxygen. What is the empirical formula of the compound?


What are electrophilic addition reactions of alkenes?


We're here to help

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

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences