Explain why the ionisation energies tend to increase across a period

As you go across a period, the next atom will have 1 more proton in its nucleus than the one before. Therefore, the nucleus of each atom will have an increasingly positive charge, meaning a stronger nuclear attraction.

Even though you also have more electrons, all of the electrons are at roughly the same energy level and so there is generally little extra shielding effect or extra distance to lessen the attraction from the nucleus.

In summary, as you go along a period, the outer electrons are more strongly attracted to a more positive nucleus and so it takes more energy to remove it from the outer shell, hence a higher ionisation energy. 

Answered by Megan S. Chemistry tutor

1879 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

Explain why phenol is nitrated more readily than benzene.


What is the difference between a sigma and pi bond? Use your answer to explain why there is fixed rotation about the C=C bond.


What is a buffer and what do you need to make one?


What is clonal selection?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences