📚 Year 8 OCR Chemistry: Key Terms Quick-Study | Year 8 OCR 化学：核心术语速记指南
Mastering chemistry starts with understanding the fundamental vocabulary. This quick-study guide covers the essential terms you will encounter in Year 8 OCR Chemistry, with clear definitions in both English and Chinese to help you memorise them effectively.
掌握化学从理解基本词汇开始。本速记指南涵盖了Year 8 OCR化学中你会遇到的核心术语，并提供清晰的中英文释义，帮助你高效记忆。
1. Atoms, Elements and Molecules | 原子、元素与分子
Everything in the universe is made of tiny particles. The key building blocks are atoms, which can combine to form elements and molecules.
宇宙万物由微小粒子构成。最基本的构件是原子，原子可以结合形成元素和分子。
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Atom: The smallest unit of an element that retains its chemical properties. It consists of a nucleus and electrons.
原子：保持元素化学性质的最小单元。它由原子核和电子组成。
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Element: A pure substance made of only one type of atom. Examples include oxygen (O) and iron (Fe).
元素：仅由一种原子组成的纯净物。例如氧(O)和铁(Fe)。
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Molecule: Two or more atoms chemically bonded together, which can be the same element (e.g. O₂) or different elements (e.g. H₂O).
分子：两个或更多原子通过化学键结合在一起的粒子，可以是同种元素(如O₂)，也可以是不同元素(如H₂O)。
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Symbol: A one- or two-letter abbreviation for an element, e.g. C for carbon, Na for sodium.
符号：元素的单字母或双字母缩写，如碳为C，钠为Na。
2. The Periodic Table | 元素周期表
The periodic table organises all known elements according to their properties.
元素周期表根据性质将所有已知元素进行排列。
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Period: A horizontal row in the periodic table. Elements in the same period have the same number of electron shells.
周期：周期表中的横行。同一周期的元素具有相同的电子层数。
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Group: A vertical column. Elements in the same group have similar chemical properties because they have the same number of electrons in their outer shell.
族：周期表中的纵列。同一族的元素化学性质相似，因为它们的最外层电子数相同。
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Metal: Elements that are typically shiny, good conductors of heat and electricity, and malleable (e.g. copper, gold).
金属：通常有光泽、导热导电性好、具有延展性的元素(如铜、金)。
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Non-metal: Elements that are poor conductors and often brittle when solid (e.g. sulfur, oxygen).
非金属：导电导热性差、固态时通常较脆的元素(如硫、氧)。
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Noble gases: Group 0 elements that are unreactive because their outer shell is full (e.g. helium, neon).
稀有气体：第0族元素，因最外层电子已满而不易反应(如氦、氖)。
3. Compounds and Chemical Formulae | 化合物与化学式
When different elements join chemically, they form compounds. A chemical formula shows the elements in a compound and their ratios.
不同元素通过化学结合会形成化合物。化学式表示化合物中的元素及其原子个数比。
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Compound: A substance made of two or more different elements chemically bonded together, e.g. water (H₂O) and carbon dioxide (CO₂).
化合物：由两种或以上不同元素通过化学键结合而成的物质，如水(H₂O)和二氧化碳(CO₂)。
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Chemical formula: A combination of symbols and numbers that shows the types and numbers of atoms in a compound. The subscript (e.g. the ‘2’ in H₂O) indicates the number of atoms.
化学式：用符号和数字表示化合物中原子种类和数目的式子。下标（如H₂O中的’2’）表示原子个数。
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Ion: A charged particle formed when an atom gains or loses electrons. Cations are positive, anions are negative.
离子：原子得或失电子后形成的带电粒子。阳离子带正电，阴离子带负电。
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Lattice: A regular repeating arrangement of particles (atoms, ions or molecules) in a solid.
晶格：固体中粒子(原子、离子或分子)有规律的重复排列。
4. Mixtures and Separation Techniques | 混合物与分离技术
Not all substances are pure; mixtures contain different substances mingled together without chemical bonding.
并非所有物质都是纯净的；混合物是由不同物质混合而成，没有发生化学结合。
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Mixture: Two or more substances that are not chemically joined and can be separated by physical methods. Air is a mixture of gases.
混合物：两种或以上物质未通过化学键结合，可通过物理方法分离。空气是一种气体混合物。
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Filtration: A separation method using a filter to separate an insoluble solid from a liquid (e.g. sand from water).
过滤：利用滤纸等过滤介质将不溶性固体与液体分离的方法(如从水中分离沙子)。
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Distillation: Separating a liquid from a mixture by boiling and condensing the vapour. Simple distillation separates a solvent from dissolved solids.
蒸馏：通过沸腾和冷凝蒸气从混合物中分离液体的方法。简单蒸馏可从溶液中分离出溶剂。
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Chromatography: A technique used to separate dissolved substances, often coloured dyes, as they move through a medium at different speeds.
色谱法：一种分离溶解物质的技术，常用于分离染料，利用不同物质在介质中移动速度的差异。
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Pure substance: A single element or compound with a fixed composition and sharp melting/boiling points.
纯净物：具有固定组成和明确熔沸点的单一元素或化合物。
5. Physical and Chemical Changes | 物理变化与化学变化
Changes to materials can be classified as physical or chemical.
物质的变化可分为物理变化和化学变化。
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Physical change: A change in which no new substance is formed. The change is often reversible, e.g. melting ice or dissolving salt in water.
物理变化：没有新物质生成的变化，通常是可逆的，如冰融化或食盐溶于水。
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Chemical change: A change that produces one or more new substances, often irreversible. Signs include colour change, gas production, or temperature change.
化学变化：生成一种或多种新物质的变化，通常不可逆。特征包括颜色改变、产生气体或温度变化。
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Reactant: A starting substance in a chemical reaction.
反应物：化学反应中起始的物质。
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Product: A substance formed in a chemical reaction.
生成物：化学反应中生成的物质。
6. Word Equations and Reactions | 文字方程式与反应
We use word equations to describe chemical reactions simply.
我们用文字方程式简单地描述化学反应。
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Word equation: An equation in which the names of the reactants and products are written in words, with an arrow showing the direction. Example: methane + oxygen → carbon dioxide + water.
文字方程式：用文字写出反应物和生成物的名称，并用箭头表示方向的方程式。例如：甲烷 + 氧气 → 二氧化碳 + 水。
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Conservation of mass: The total mass of reactants equals the total mass of products; atoms are recycled, not created or destroyed.
质量守恒：反应物的总质量等于生成物的总质量；原子重新组合，不会凭空产生或消失。
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Exothermic reaction: A reaction that releases heat energy to the surroundings (e.g. burning fuels).
放热反应：向环境释放热能的反应(如燃料燃烧)。
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Endothermic reaction: A reaction that absorbs heat energy from the surroundings (e.g. photosynthesis).
吸热反应：从环境吸收热能的反应(如光合作用)。
7. Acids and Alkalis | 酸与碱
Acids and alkalis are chemical opposites, each with distinct properties.
酸和碱在化学上性质相反，各有特点。
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Acid: A substance that produces hydrogen ions (H⁺) in water. It tastes sour and turns blue litmus paper red. Common lab acids:
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