CAIE A-Level Chemistry 1.4.3 Ionisation-Energy Trends
Practise explaining general changes across periods and down groups while accounting for sub-shell and pairing anomalies.
- Syllabus
- 2028–2030
- Course
- Chemistry 9701
- Level
- AS
Exam points
- explain the general increase across a period by increasing nuclear charge with similar shielding and shell distance
- explain the general decrease down a group by greater distance and shielding despite higher nuclear charge
- explain small anomalies using entry into a higher-energy p sub-shell or repulsion between paired electrons
1.4.3—The trends in ionisation energies across question 1
The Periodic Table is arranged such that the properties of the elements show a number of trends.
Question (a)
(a)
A plot of the first ionisation energies for the first 18 elements is shown.
[ 4 ]
Question (i)
(i)
Explain why the values show a general increase from atomic number 11 to 18 .
[ 2 ]
Question (ii)
(ii)
Suggest an explanation for the trend in the first ionisation energies of the elements with atomic numbers 2, 10 and 18.
[ 2 ]
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