Question 1Multiple choice · 1 markA* challenge
What is the electronic configuration of Mn2+?
- A [Ar] 3d3 4s2
- B [Ar] 3d4 4s1
- C [Ar] 3d5
- D [Ar] 3d7
Show answer
Answer: C
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Answer: C
Which term is described by this statement?
“A region that can hold up to two electrons of opposite spin.”
Answer: B
Across Period 3 from sodium to argon, the first ionisation energy generally increases.
1 The decrease from magnesium to aluminium occurs because the 3p electron is at a higher energy than the 3s electrons.
2 Atomic radius increases across the period.
3 The decrease from phosphorus to sulfur is due to repulsion between paired electrons in a 3p orbital.
Which statements are correct?
Answer: B
The first five successive ionisation energies of an element X, in kJ mol−1, are
496, 4562, 6910, 9543, 13354.
In which group of the Periodic Table is X?
Answer: A
The successive ionisation energies, in kJ mol−1, of a Period 3 element X are: 578, 1817, 2745, 11577.
Write an equation, with state symbols, for the second ionisation energy of X.
Deduce the group of X, explaining your reasoning.
Explain why the first ionisation energy of aluminium is lower than that of magnesium.
Explain why the first ionisation energy of sulfur is lower than that of phosphorus.
Give the full electronic configuration of aluminium.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | X⁺(g) → X²⁺(g) + e⁻ X⁺(g) → X²⁺(g) + e⁻ B1 | 1 |
| (b) | Group 13 large jump after the 3rd electron so 3 outer electrons M1 Group 13 so X is aluminium A1 | 2 |
| (c) | 3p electron higher energy, shielded by 3s the outer electron of Al is in a 3p orbital, higher in energy than 3s M1 and is shielded by the 3s electrons M1 | 2 |
| (d) | spin-pair repulsion sulfur has a pair of electrons in one 3p orbital M1 repulsion between the paired electrons makes one easier to remove M1 | 2 |
| (e) | 1s² 2s² 2p⁶ 3s² 3p¹ 1s² 2s² 2p⁶ 3s² 3p¹ B1 | 1 |
The first ionisation energies of the elements show trends across periods and down groups.
Define the first ionisation energy.
Explain why the first ionisation energy of oxygen is lower than that of nitrogen.
Write the full electronic configuration of Fe³⁺.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | energy to remove one electron from each atom in one mole of gaseous atoms energy required to remove one electron B1 from each atom in one mole of gaseous atoms B1 to form one mole of gaseous 1+ ions B1 | 3 |
| (b) | spin-pair repulsion in 2p oxygen has a pair of electrons in one 2p orbital B1 repulsion between paired electrons makes one easier to remove B1 | 2 |
| (c) | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ B1 | 1 |
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