Explain why the electrical conductivity of copper is much greater than that of manganese, despite both being transition metals in the same period.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Copper has an anomalous electron configuration of [Ar] 3d¹⁰ 4s¹, whilst manganese has the configuration [Ar] 3d⁵ 4s². At 20 °C, copper conducts electricity approximately 50 times better than manganese.
Model answer (4 marks)
Metals conduct electricity because delocalised electrons are free to move through the lattice and act as charge carriers.
Copper supplies only one valence electron to the delocalised sea (4s¹), whereas manganese supplies two (4s²). The difference in conductivity cannot be explained by valence‑electron count alone; the key factor is the extent of electron scattering.
Copper has a completely filled 3d subshell (3d¹⁰), giving a spherically symmetric and more uniform ion core. This reduces the scattering of delocalised electrons, lowering the resistance.
Therefore copper has a much lower electrical resistivity (and higher conductivity) than manganese because its delocalised electrons experience less scattering as they move through the lattice.
Copper supplies only one valence electron to the delocalised sea (4s¹), whereas manganese supplies two (4s²). The difference in conductivity cannot be explained by valence‑electron count alone; the key factor is the extent of electron scattering.
Copper has a completely filled 3d subshell (3d¹⁰), giving a spherically symmetric and more uniform ion core. This reduces the scattering of delocalised electrons, lowering the resistance.
Therefore copper has a much lower electrical resistivity (and higher conductivity) than manganese because its delocalised electrons experience less scattering as they move through the lattice.
Examiner tips
- Mention delocalised electrons as charge carriers first. Explain the role of the filled 3d shell in reducing scattering. Show the comparison of valence electrons but note it is not the decisive factor. Conclude with lower resistivity / higher conductivity.
Common mistakes
- Confusing valence‑electron count as the sole reason for conductivity. Forgetting to mention the filled 3d subshell and its effect on scattering. Using vague terms like "more electrons" without explaining scattering.
Mark scheme (4 marks)
- Metals conduct electricity because delocalised electrons are free to move through the lattice / act as charge carriers.
- Copper contributes only one valence electron to the delocalised sea (from 4s¹), whereas manganese contributes two (from 4s²), so the difference in conductivity cannot be explained by valence electron count alone; the key factor is the extent of electron scattering.
- Copper's completely filled 3d subshell (3d¹⁰) produces a spherically symmetric / more uniform ion core, resulting in less scattering of delocalised electrons and therefore lower resistance.
- Therefore copper has a much lower electrical resistivity / higher conductivity because the delocalised electrons experience less scattering as they move through the lattice.
Key terms in this question
Related
- All IB DP Chemistry Higher Level (2023 syllabus) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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