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CAIE A-Level Chemistry AS 1.4 Ionisation Energy Questions

Practise definitions, gas-phase equations, periodic trends and successive-ionisation data using nuclear attraction and shielding.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • state the full first-ionisation-energy definition and construct gas-phase electron-removal equations
  • explain trends using nuclear charge, distance, shielding, sub-shell energy and electron pairing
  • use large jumps in successive values to infer valence-electron number and electronic structure

Covered syllabus points

1.4.0—Scope note1.4.1—Terms: first ionisation energy, IE1.4.2—Equations to represent first, second1.4.3—The trends in ionisation energies across1.4.4—The variation in successive ionisation1.4.5—Ionisation energies are due to the attraction1.4.6—Factors influencing the ionisation energies1.4.7—The electronic configurations of elements1.4.8—Periodic Table position from IE data

Question 1

[Maximum number: 1]

Equations involving four enthalpy changes are shown.

Na( g)→Na+(g)+e−ΔH=WNa( g)→Na2+(g)+2e−ΔH=XNa( s)→Na( g)ΔH=YNa( s)→Na2+(g)+2e−ΔH=Z\begin{array}{ll} \mathrm{Na}(\mathrm{~g}) \rightarrow \mathrm{Na}^{+}(\mathrm{g})+\mathrm{e}^{-} & \Delta H=\mathrm{W} \\ \mathrm{Na}(\mathrm{~g}) \rightarrow \mathrm{Na}^{2+}(\mathrm{g})+2 \mathrm{e}^{-} & \Delta H=\mathrm{X} \\ \mathrm{Na}(\mathrm{~s}) \rightarrow \mathrm{Na}(\mathrm{~g}) & \Delta H=\mathrm{Y} \\ \mathrm{Na}(\mathrm{~s}) \rightarrow \mathrm{Na}^{2+}(\mathrm{g})+2 \mathrm{e}^{-} & \Delta H=\mathrm{Z} \end{array}

Which equation represents the second ionisation energy of sodium?

A

X

B

X+Y-W

C

X-W

D

Z-W

Question 2

[Maximum number: 1]

This question is about the first ionisation energies of magnesium and neon.
Which row is correct?

from Mg

from Ne

p

s

s

p

p

s

S

p

Question 3

[Maximum number: 1]

Which process has the largest enthalpy change per mole?

A

All3+(g)→All4+(g)+e−\mathrm{Al} l^{3+}(\mathrm{g}) \rightarrow \mathrm{Al} l^{4+}(\mathrm{g})+\mathrm{e}^{-}

B

P5+(g)→P6+(g)+e−\mathrm{P}^{5+}(\mathrm{g}) \rightarrow \mathrm{P}^{6+}(\mathrm{g})+\mathrm{e}^{-}

C

S6+(g)→S7+(g)+e−\mathrm{S}^{6+}(\mathrm{g}) \rightarrow \mathrm{S}^{7+}(\mathrm{g})+\mathrm{e}^{-}

D

Si4+(g)→Si5+(g)+e−\mathrm{Si}^{4+}(\mathrm{g}) \rightarrow \mathrm{Si}^{5+}(\mathrm{g})+\mathrm{e}^{-}

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