IGCSE CAIE Chemistry 是综合性最强的理科——兼顾概念理解、精确计算与大量记忆。CAIE 考试 Paper 2（选择）、Paper 4（简答）和 Paper 6（实验替代）各有独特提分策略。本文系统梳理六大高分模块，助你精准发力，冲刺 A*。
一、摩尔计算：高分命门
摩尔（mole）是整个化学体系的基石。掌握 n = m / Mᵣ（物质的量 = 质量 ÷ 摩尔质量）和 n = V / 24 dm³（RTP下气体摩尔体积），就能打通 Stoichiometry 大题。解题四步法：写方程式 → 算摩尔数 → 摩尔比换算 → 求目标质量。Limiting reactant 和 percentage yield = (actual / theoretical) × 100% 是 Paper 4 必考。
The mole concept underpins all Stoichiometry. Master n = m / Mᵣ and n = V / 24 dm³, then follow the four-step method: write equation → calculate moles → apply mole ratio → find target mass. Percentage yield and limiting reactant are guaranteed in Paper 4.
二、化学键与结构
离子键（ionic）：金属与非金属间电子转移，形成 giant ionic lattice。共价键（covalent）：非金属原子共享电子。金属键（metallic）：阳离子浸泡在离域电子海中。画 dot-and-cross 图时，离子化合物必须用方括号标电荷 [Na]⁺ [:Cl:]⁻，漏一个符号整图零分。必背 Diamond vs Graphite 导电性对比：Graphite 因每碳原子仅3个价电子成键、1个离域电子可自由移动而导电；Diamond 无自由电子故不导电。
Three bond types: ionic (electron transfer, giant lattice), covalent (electron sharing), metallic (sea of delocalised electrons). Dot-and-cross diagrams demand brackets and charges for ionic compounds — one missing symbol loses all marks. Diamond vs Graphite: graphite conducts due to one delocalised electron per carbon; diamond does not.
三、平衡与速率
Le Chatelier 原理核心：系统受外界条件改变时，平衡向抵消该改变的方向移动。催化剂只加速反应、不改变平衡位置，这是 Paper 2 经典陷阱。Haber process（N₂ + 3H₂ ⇌ 2NH₃）实际条件 450°C / 200 atm / iron catalyst 是速率、产率和成本的折中。Contact process 使用 V₂O₅ 催化剂。碰撞理论答案模板：升温 → 粒子动能增大 → 碰撞频率和有效碰撞均增加 → 速率加快。关键词：more kinetic energy, more frequent collisions, activation energy。
Le Chatelier's Principle: equilibrium shifts to oppose imposed changes. Catalysts affect rate only, not equilibrium position — a classic Paper 2 trap. Haber process conditions (450°C, 200 atm, iron) balance rate, yield, and cost. Collision theory template: higher temperature → more kinetic energy → more frequent and effective collisions.
四、酸碱盐与电解
盐的制备方法：可溶性盐用 acid + insoluble base（过量固体法），不溶性盐用 precipitation，钠钾铵盐只能用 titration。电解核心：molten 时产物确定；aqueous 时 H⁺ 和 OH⁻ 参与竞争，用 reactivity series 判阴极产物，anion discharge series (SO₄²⁻ < NO₃⁻ < Cl⁻ < Br⁻ < I⁻ < OH⁻) 判阳极产物。电镀和铝的提取装置图必须会画。
Salt prep: soluble → excess solid method; insoluble → precipitation; Group I / ammonium salts → titration only. Electrolysis in aqueous solution: H⁺ and OH⁻ compete; use reactivity series for cathode, discharge series for anode. Electroplating and bauxite extraction diagrams are essential.
五、有机化学
IGCSE 有机涉及 alkanes、alkenes、alcohols、carboxylic acids 四个 homologous series。溴水实验区分 alkane/alkene：alkane 需 UV light 才褪色（substitution），alkene 常温即褪色（addition）。Addition polymerisation 产物须画 repeating unit 加方括号和下标 n。发酵方程式：C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂。Ethanol 氧化生成 ethanoic acid，用 acidified KMnO₄（紫→无色）。
Four homologous series: alkanes, alkenes, alcohols, carboxylic acids. Bromine water test: alkanes decolourise only under UV (substitution); alkenes instantly (addition). Fermentation: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. Oxidation of ethanol uses acidified KMnO₄ (purple → colourless).
六、三卷差异化策略
Paper 2（40题/45分钟）：每题67秒，卡壳即跳，全部做完再回头。排除法依次否定干扰项。Paper 4（80分/1h15m）：科学术语精确至上。解释离子化合物高熔点须包含六个关键词：strong, electrostatic, attraction, oppositely charged, ions, overcome。Paper 6（40分/1h）：画图用铅笔直尺，标注精确（如 conical flask），坐标轴标物理量和单位，数据点用 ×，best-fit line 不强求过所有点。
Paper 2: 67s per question — skip and return. Paper 4: precise terminology wins; the six keywords for ionic melting point (strong, electrostatic, attraction, oppositely charged, ions, overcome) are all essential. Paper 6: pencil and ruler for apparatus; axes need quantity and unit; best-fit line need not hit every point.
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