📚 Year 12 Cambridge Chemistry: Key Vocabulary Memorisation Guide | 剑桥12年级化学：核心词汇速记指南
Mastering terminology is half the battle in Cambridge AS Level Chemistry. This guide links each key term to a memory hook, root word or pattern so you can recall definitions quickly under exam pressure.
在剑桥 AS 化学中，掌握术语就是成功的一半。这份指南为每个核心术语搭配了记忆挂钩、词根或规律，帮助你在考试压力下迅速回忆起定义。
1. Atomic Structure & the Periodic Table | 原子结构与周期表
Atom: The smallest unit of an element that still shows its chemical properties. Think of the Greek atomos – ‘indivisible’.
原子：保持元素化学性质的最小单位。联想希腊语 atomos ——“不可分割”，就像一颗无法再切的小球。
Isotope: Atoms of the same element (same proton number) but different numbers of neutrons. ‘Iso-‘ means equal, ‘topos’ means place – they occupy the same place on the periodic table.
同位素：质子数相同但中子数不同的同种原子。“Iso-”表示“相同”，“topos”表示“位置”——它们在周期表中占据同一位置。
Relative atomic mass (Aᵣ): The weighted average mass of an element’s isotopes relative to 1/12th the mass of a carbon‑12 atom. Mnemonic: Aᵣ = r for ‘relative’, compared to C‑12.
相对原子质量 (Aᵣ)：元素同位素质量的加权平均值，以碳‑12 原子质量的 1/12 为标准。记忆：Aᵣ 中的 r 代表“相对”。
First ionisation energy: The energy needed to remove one mole of electrons from one mole of gaseous atoms. Visualise pulling an electron away against the nuclear pull.
第一电离能：从一摩尔气态原子中移走一摩尔电子所需的能量。想象把电子从原子核的引力中拉走。
Electron configuration: Written as 1s² 2s² 2p⁶ … Use the ‘filling order’ diagram or the phrase ‘1s, 2s, 2p, 3s, 3p, 4s, 3d’ as a chant.
电子排布：写为 1s² 2s² 2p⁶……可以背诵填充顺序口诀：“1s、2s、2p、3s、3p、4s、3d”。
2. Chemical Bonding & Structure | 化学键与结构
Ionic bond: Electrostatic attraction between oppositely charged ions formed by electron transfer. ‘Ionic’ reminds you of ions; a metal gives, a non‑metal takes.
离子键：通过电子转移形成的带相反电荷离子之间的静电引力。“离子”提示了带电粒子；金属给出电子，非金属获得电子。
Covalent bond: A shared pair of electrons between two non‑metal atoms. ‘Co-‘ means together; ‘valent’ relates to valence electrons.
共价键：两个非金属原子间共用的一对电子。“Co-”表示共同，“valent”与价电子有关。
Metallic bonding: Attraction between a lattice of positive metal ions and a ‘sea’ of delocalised electrons. Picture a grid of cations floating in a mobile electron sea.
金属键：正金属离子晶格与离域电子“海洋”之间的吸引力。想象阳离子网络漂浮在流动的电子海洋中。
Electronegativity: The power of an atom to attract the bonding pair of electrons in a covalent bond. Think ‘electron‑negative‑ity’ – the stronger pull makes a partial negative charge.
电负性：原子在共价键中吸引电子对的能力。想象“电子‑负电‑性”，更强的吸引力带来部分负电荷。
VSEPR theory: Valence Shell Electron Pair Repulsion. Pairs of electrons (bonding or lone) repel each other and arrange as far apart as possible. Say ‘VES‑per’ to recall the acronym.
价层电子对互斥理论 (VSEPR)：价层电子对（成键或孤对）互相排斥，并尽可能远离。念作“VES‑per”即可记住缩写。
Shapes: Linear (2 pairs, 180°), trigonal planar (3 pairs, 120°), tetrahedral (4 pairs, 109.5°). Count the electron clouds and assign the shape.
分子形状：直线形（2 对，180°）、平面三角形（3 对，120°）、四面体形（4 对，109.5°）。数一数电子云区域即可确定形状。
| Shape / 形状 | Bond angle / 键角 | Example / 示例 |
| Linear / 直线形 | 180° | BeCl₂, CO₂ |
| Trigonal planar / 平面三角形 | 120° | BF₃ |
| Tetrahedral / 四面体形 | 109.5° | CH₄ |
3. The Mole Concept & Stoichiometry | 摩尔概念与化学计量
Mole (mol): The amount of substance containing exactly 6.02 × 10²³ elementary entities. Think of a ‘mole’ as a chemist’s dozen – a huge but fixed number.
摩尔：含有恰好 6.02×10²³ 个基本单元的物质的量。把“摩尔”想象成化学家的“打”，一个极大但固定的数目。
Avogadro constant (NA): 6.02 × 10²³ mol⁻¹. It bridges the atomic and macroscopic worlds. Remember ‘Avogadro’ sounds like ‘avocado’ – a single avocado contains about one avocado, but a mole is much larger!
阿伏伽德罗常数 (Nₐ)：6.02×10²³ mol⁻¹，连接微观原子与宏观世界的桥梁。读音类似“avocado”，但一颗鳄梨只是一个，一摩尔可是海量。
Empirical formula: The simplest whole‑number ratio of atoms in a compound. Think ’empirical = elementary ratio’.
实验式：化合物中各原子最简整数比。记忆：“实验式”即“最简比例式”。
Limiting reactant: The reactant that runs out first and determines the theoretical yield. Picture a sandwich recipe: if you run out of bread, bread is the limiting ingredient.
限制反应物：最先耗尽并决定理论产率的反应物。想象做三明治，面包用完了，面包就是“限制成分”。
n = m / M
n (amount in mol) = mass (g) ÷ molar mass (g mol⁻¹)
4. Energetics & Thermochemistry | 热化学与能量学
Enthalpy change (ΔH): The heat transferred in a reaction at constant pressure. ΔH = H(products) – H(reactants). If ΔH is negative, the reaction gives out heat (exothermic).
焓变 (ΔH)：恒压条件下反应的热量变化。ΔH = 生成物焓 – 反应物焓。ΔH 为负，反应放热。
Activation energy (Eₐ): The minimum energy colliding particles need to start a reaction. Imagine a hill: Eₐ is the height you must climb before rolling down.
活化能 (Eₐ)：碰撞粒子启动反应所需的最低能量。想象一座小山，Eₐ 就是必须翻过的高度。
Standard enthalpy of combustion (ΔHc⦵): The enthalpy change when one mole of a substance burns completely in oxygen under standard conditions. All products in their standard states.
标准燃烧焓 (ΔHc⦵)：标准状态下，一摩尔物质在氧气中完全燃烧的焓变。所有产物处于标准态。
Hess’s Law: The total enthalpy change for a reaction is independent of the route taken. Draw a cycle: route 1 = route 2. Think ‘Hess’s law – hassle‑free arithmetic with arrows’.
盖斯定律：反应的总焓变与途径无关。画一个循环图，路径 1 等于路径 2。记忆：“盖斯定律——用箭头做轻松算术”。
Standard conditions: 100 kPa pressure, 298 K (25 °C), and solutions at 1 mol dm⁻³. Mark these numbers in your memory as ‘100‑298‑1’.
标准条件：100 kPa，298 K (25 °C)，溶液浓度 1 mol dm⁻³。用数字组合“100‑298‑1”帮助记忆。
5. Reaction Kinetics | 反应动力学
Rate of reaction: The change in concentration of a reactant or product per unit time. Remember: rate depends on collision frequency and successful collisions.
反应速率：单位时间内反应物或产物浓度的变化。记忆：速率取决于碰撞频率和有效碰撞。
Catalyst: A substance that speeds up a reaction without being chemically changed itself. It provides an alternative pathway with lower Eₐ. Mnemonic: ‘Cat’ – a cat runs fast, and a catalyst speeds things up.
催化剂：加快反应速率而自身化学性质不变的物质。它提供一条更低活化能的替代路径。联想：Catalyst 像“猫”（cat），跑得快。
Maxwell‑Boltzmann distribution: A curve showing the range of kinetic energies among gas molecules. Only particles with energy ≥ Eₐ can react. Adding a catalyst shifts the Eₐ line to the left, increasing the number of successful particles.
麦克斯韦‑玻尔兹曼分布：显示气体分子动能范围的曲线。只有能量 ≥ Eₐ 的粒子才能反应。催化剂使 Eₐ 线左移，成功粒子数增加。
Homogeneous catalyst: A catalyst in the same phase as the reactants. Heterogeneous catalyst: in a different phase. ‘Homo’ = same, ‘hetero’ = different.
均相催化剂：与反应物同相的催化剂。多相催化剂：与反应物不同相。“Homo”同，“hetero”异。
6. Chemical Equilibrium | 化学平衡
Dynamic equilibrium: The forward and reverse reactions occur at equal rates, so macroscopic concentrations stay constant but molecules keep reacting. Picture two identical queues moving at the same speed in opposite directions.
动态平衡：正逆反应速率相等，宏观浓度不变，但分子仍在不断反应。想象两条反向移动但速度相同的队列。
Le Chatelier’s Principle: When a system at equilibrium is disturbed, it shifts to oppose the change. Mnemonic: ‘Le Chatelier = the system likes to compensate’.
勒夏特列原理：当平衡系统受到扰动时，系统会向减弱该扰动的方向移动。记忆：“勒夏特列——系统总想补偿”。
Equilibrium constant Kc: For aA + bB ⇌ cC + dD, Kc = [C]ᶜ [D]ᵈ / [A]ᵃ [B]ᵇ. Products over reactants, raised to stoichiometric powers. Value > 1 means product‑favored.
平衡常数 Kc：对于 aA + bB ⇌ cC + dD，Kc = [C]ᶜ[D]ᵈ / [A]ᵃ[B]ᵇ。生成物浓度幂次除以反应物浓度幂次。Kc > 1 表示偏向生成物。
Effect of temperature on Kc: Only temperature changes Kc. For endothermic forward reactions, raising T increases Kc. Think ‘heat is a reactant for endo; adding heat shifts to products’.
温度对 Kc 的影响：只有温度能改变 Kc。正向吸热反应，升温使 Kc 增大。将热量视为吸热反应的反应物，加入热量使平衡向右移动。
7. Acids, Bases & pH | 酸、碱与 pH
Brønsted‑Lowry acid: A proton (H⁺) donor. Base: a proton acceptor. Use the simple rhyme: ‘Acid Donates, Base Accepts’.
布朗斯特‑劳里酸：质子 (H⁺) 给予体。碱：质子接受体。口诀：“酸给碱接”。
Conjugate acid‑base pair: Two species that differ by one proton. E.g., HCl and Cl⁻. The conjugate base of a strong acid is a very weak base.
共轭酸碱对：相差一个质子的两种物种。如 HCl 和 Cl⁻。强酸的共轭碱是极弱碱。
pH: pH = −log₁₀[H⁺]. ‘p’ stands for ‘‑log₁₀’, so pOH = −log₁₀[OH⁻]. Low pH = high [H⁺] = acidic.
pH：pH = −log₁₀[H⁺]。“p”代表“‑log₁₀”，因此 pOH = −log₁₀[OH⁻]。pH 低则 [H⁺] 高，呈酸性。
Ionic product of water, Kw: Kw = [H⁺][OH⁻] = 1.0 × 10⁻¹⁴ at 298 K. In pure water, [H⁺] = [OH⁻] = 1.0 × 10⁻⁷ mol dm⁻³.
水的离子积 Kw：Kw = [H⁺][OH⁻] = 1.0×10⁻¹⁴ (298 K)。纯水中 [H⁺] = [OH⁻] = 1.0×10⁻⁷ mol dm⁻³。
Strong vs weak acid: A strong acid fully dissociates (HCl → H⁺
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