Year 12 OCR Chemistry: High-Frequency Topics & Common Mistakes | Year 12 OCR 化学：高频考点与易错题分析

📚 Year 12 OCR Chemistry: High-Frequency Topics & Common Mistakes | Year 12 OCR 化学：高频考点与易错题分析

Mastering Year 12 OCR Chemistry requires not only understanding core concepts but also identifying where students commonly lose marks. This revision article dissects the high-frequency topics and the most frequent mistakes from across the specification, allowing you to target your weaknesses and maximise your exam performance.

掌握 Year 12 OCR 化学不仅需要理解核心概念，还要能够识别考生常见的失分点。本文剖析了考纲中的高频考点与最易出错的地方，帮助你精准攻克薄弱环节，在考试中发挥最佳水平。

1. Atomic Structure & Electron Configurations | 原子结构与电子排布

Students often lose marks by ignoring the exceptional electron configurations of chromium and copper. The ground-state configuration of Cr is [Ar] 3d⁵ 4s¹, not [Ar] 3d⁴ 4s², because a half-filled d subshell provides extra stability. Similarly, Cu is [Ar] 3d¹⁰ 4s¹ instead of [Ar] 3d⁹ 4s². When forming ions, transition metals lose their 4s electrons first. For example, Fe²⁺ is [Ar] 3d⁶, not [Ar] 3d⁴ 4s². Another common error is writing the configuration of simple ions: O²⁻ gains electrons to become 1s² 2s² 2p⁶, which is isoelectronic with Ne.

常见的失分点是忽略铬和铜原子特殊的电子排布。Cr 的基态电子排布是 [Ar] 3d⁵ 4s¹，而不是 [Ar] 3d⁴ 4s²，因为 3d 轨道半充满带来了额外的稳定性。同样，Cu 为 [Ar] 3d¹⁰ 4s¹，而不是 [Ar] 3d⁹ 4s²。形成离子时，过渡金属先失去 4s 电子。例如 Fe²⁺ 的排布是 [Ar] 3d⁶，而非 [Ar] 3d⁴ 4s²。另一个常见错误是书写简单离子的排布：O²

Published by TutorHao | Year 12 Chemistry Revision Series | aleveler.com

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