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Edexcel A Level Chemistry (9CH0)

Ionisation Energy

Ionisation energy measures the energy required to remove an electron from a gaseous atom or ion. These pages build from the definition of first ionisation energy through to successive ionisation energy patterns and the main periodic trends across a period and down a group.

Exam Paper
Paper 1
9CH0/01 – Advanced Inorganic and Physical Chemistry
Specification Points
15 – 25
6 points covered
Sub-topics
4 lessons
Revision notes available
Exam Board
Edexcel
Pearson 9CH0

Revision Notes

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Electron removal
First
Ionisation
definition, state symbols and attraction
1

Introduction to Ionisation Energy

Revise the definition of first ionisation energy, state symbols and the factors that affect electron removal.

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Energy jumps
Successive
Values
large jumps reveal electron shells
2

Successive Ionisation Energies

Use successive ionisation energy data to identify electron shells, group number and large jumps between energy levels.

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Across a period
Period
Trends
nuclear charge, radius and subshells
3

Trends in a Period

Explain why first ionisation energy generally increases across a period, including the small drops at key points.

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Down a group
Group
Trends
shielding and atomic radius increase
4

Trends in a Group

Explain why first ionisation energy decreases down a group as shielding and atomic radius increase.

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Summary map

Download, print and revise the key facts of this topic at a glance.

Summary map · PDF

Ionisation Energies and Periodicity Map

Edexcel A Level Chemistry · Topic 1 Atomic Structure · Ionisation Energies and Periodicity

The whole section on one A4 page: ionisation energies and their factors, successive IEs and emission spectra, trends, atomic radius and melting temperatures.

Download the map6 key ideas + a data table · A4 portrait · print ready

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Specification Coverage

Ionisation Energy – Edexcel A Level Chemistry (9CH0)

The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 1. All points are assessed in Paper 1 (9CH0/01).

Electron Configuration

15
understand how ideas about electronic configuration developed from:
i
the fact that atomic emission spectra provide evidence for the existence of quantum shells
ii
the fact that successive ionisation energies provide evidence for the existence of quantum shells and the group to which the element belongs
iii
the fact that the first ionisation energy of successive elements provides evidence for electron sub-shells

Ionisation Energy

11
be able to define the terms first ionisation energy and successive ionisation energies
12
understand how ionisation energies are influenced by the number of protons, the electron shielding and the electron sub-shell from which the electron is removed
13
understand reasons for the general increase in first ionisation energy across a period
14
understand reasons for the decrease in first ionisation energy down a group

Periodic Trends

25
understand reasons for the trends in the following properties of the elements from periods 2 and 3 of the Periodic Table:
i
the melting and boiling temperatures of the elements, based on given data, in terms of structure and bonding
ii
ionisation energy based on given data or recall of the plots of ionisation energy versus atomic number