Ionisation energiesEdexcel A-Level Chemistry: Flashcards

What these 12 flashcards ask

Define first ionisation energy.
Write the equation for the first ionisation energy of sodium.
Write the equation for the second ionisation energy of magnesium.
Why do successive ionisation energies increase?
What does a large jump in successive ionisation energies show?
How do you use successive ionisation energies to find the group?
What is shielding?
Why does first ionisation energy decrease down a group?
Why does first ionisation energy generally increase across a period?
Why is the first ionisation energy of Al lower than that of Mg?
What units are ionisation energies given in?
Which species must be gaseous in an ionisation energy equation?

Exam questions on Ionisation energies

Element X is in Period 3 of the periodic table. Its first five successive ionisation energies, in kJ mol⁻¹, are: 1st 738, 2nd 1451, 3rd 7733, 4th 10543, 5th 13630.
Explain why the third ionisation energy of X is much greater than its second ionisation energy.2 marks
The first ionisation energies of the Group 1 metals lithium, sodium, potassium and rubidium are 520, 496, 419 and 403 kJ mol⁻¹ respectively.
Explain why the first ionisation energy of rubidium is lower than that of sodium.2 marks
The first ionisation energies of the Period 3 elements, in kJ mol⁻¹, are: Na 496, Mg 738, Al 578, Si 786, P 1012, S 1000, Cl 1251 and Ar 1521.
Explain the general increase in first ionisation energy from sodium to argon.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).