📚 Year 9 OCR Chemistry: Vocabulary & Terminology Quick Memory Guide | Year 9 OCR 化学：词汇术语速记指南
Mastering chemistry begins with its language. This guide breaks down the essential terms you will meet in Year 9 OCR Chemistry, pairing them with simple definitions and memory tricks. By linking words to stories, pictures, and patterns, you can turn abstract vocabulary into knowledge that sticks.
学好化学，从掌握它的语言开始。本指南将 Year 9 OCR 化学中你将遇到的核心术语逐一拆解，配以简洁的定义和记忆小窍门。通过把词汇与故事、图像和规律联系起来，你可以把抽象的术语变成牢固的知识。
1. Atom, Element, Compound & Molecule | 原子、元素、化合物与分子
An atom is the smallest particle of an element that can take part in a chemical reaction. Think of it as a single Lego brick.
原子 是能参与化学反应的元素最小粒子。可以把它想象成一块乐高积木。
An element is a substance made of only one type of atom. It cannot be broken down into simpler substances by chemical means.
元素 是由同一种原子组成的物质，无法通过化学方法分解成更简单的物质。
A compound is a substance formed when atoms of two or more different elements are chemically bonded together. The properties of a compound are totally different from the elements that make it. For example, sodium is a reactive metal and chlorine is a poisonous gas, but together they form sodium chloride—table salt.
化合物 是由两种或以上不同元素的原子通过化学键结合而成的物质。化合物的性质与组成它的元素完全不同。例如，钠是活泼金属，氯是有毒气体，但两者结合却形成氯化钠——食盐。
A molecule is a group of atoms held together by covalent bonds. All compounds formed of non-metals exist as molecules, but some elements also exist as molecules, like O₂ or H₂.
分子 是由共价键结合在一起的一组原子。由非金属形成的化合物通常以分子存在，但某些单质也以分子形式存在，如 O₂ 或 H₂。
2. Subatomic Particles: Protons, Neutrons & Electrons | 亚原子粒子：质子、中子与电子
The proton is a positively charged particle found in the nucleus. Its relative mass is 1 and its charge is +1. Remember 'Pro' for Positive.
质子 是原子核中带正电的粒子，相对质量为 1，电荷为 +1。可以记作“质”谐音“正”。
The neutron has no charge (neutral) and also sits in the nucleus. Its relative mass is also 1. 'Neut' sounds like 'neutral'.
中子 不带电（中性），同样位于原子核内，相对质量也为 1。“中”即中性。
The electron is a tiny, negatively charged particle that moves around the nucleus in shells. Its relative mass is almost 0 (1/1836), and its charge is –1. Visualise electrons orbiting the nucleus like planets around the Sun.
电子 是围绕原子核在电子层中运动的极小带负电粒子，相对质量几乎为 0（1/1836），电荷为 –1。可以把电子想象成绕原子核运行的行星。
In any neutral atom, the number of protons equals the number of electrons.
在任何中性原子中，质子数等于电子数。
3. Atomic Number and Mass Number | 原子序数与质量数
The atomic number (Z) is the number of protons in an atom. It determines which element an atom is. For example, carbon has atomic number 6.
原子序数（Z）是原子中质子的数目，它决定了原子属于哪种元素。例如，碳的原子序数是 6。
The mass number (A) is the total number of protons and neutrons in the nucleus. It is always the larger of the two numbers shown with an element symbol.
质量数（A）是原子核内质子数与中子数的总和。在元素符号旁标注时，它总是较大的那个数字。
find the number of neutrons, subtract the atomic number from the mass number: neutrons = A – Z.
计算中子数的方法：中子数 = 质量数 – 原子序数（A – Z）。
4. Electron Shells and Valence Electrons | 电子层与价电子
Electrons are arranged in shells around the nucleus. The first shell can hold up to 2 electrons, the second up to 8, and the third up to 8 at this stage. The electronic configuration of sodium (11 electrons) is written as 2,8,1.
电子以电子层的形式分布在原子核周围。第一层最多容纳 2 个电子，第二层最多 8 个，现阶段第三层也按最多 8 个对待。钠（11 个电子）的电子排布写作 2,8,1。
The electrons in the outermost shell are called valence electrons. These are the electrons involved in bonding and chemical reactions. Elements in the same group of the periodic table have the same number of valence electrons, which explains similar chemical behaviour.
最外层的电子称为价电子，它们参与化学键的形成和化学反应。周期表中同族元素具有相同的价电子数，这也是它们化学性质相似的原因。
5. Ions and Ionic Bonding | 离子与离子键
An ion is a charged particle that forms when an atom gains or loses electrons. Loss of electrons creates a positive ion (cation), gain creates a negative ion (anion). The memory phrase 'CATions are PUSsy' reminds you that cations are positive (+).
离子 是原子得到或失去电子后形成的带电粒子。失去电子形成阳离子（正离子），得到电子形成阴离子（负离子）。可记为“阳”谐音“正”，与英文 CATions are POSitive 中的 P 呼应。
Ionic bonding occurs between a metal and a non-metal. Metals lose electrons to become positive ions; non-metals gain those electrons to become negative ions. The strong electrostatic attraction between opposite charges holds the ions together in a giant ionic lattice.
离子键 存在于金属与非金属之间。金属失去电子变成正离子，非金属得到电子变成负离子；异种电荷间的强静电引力将这些离子固定在巨大的离子晶格中。
Example: In sodium chloride, Na loses 1 electron to form Na⁺, and Cl gains 1 electron to form Cl⁻.
例如：在氯化钠中，钠原子失去 1 个电子形成 Na⁺，氯原子得到 1 个电子形成 Cl⁻。
6. Covalent Bonding and Simple Molecules | 共价键与简单分子
Covalent bonding their outer shells, forming a molecule. A single covalent bond is one shared pair (e.g., H–H); a double bond is two shared pairs (e.g., O=O).
共价键 存在于非金属原子之间。原子通过共享电子对来填满各自的最外层，形成分子。单根共价键由一对共享电子构成（如 H–H）；双键由两对共享电子构成（如 O=O）。
Substances made of simple molecules have low melting and boiling points because the intermolecular forces between molecules are weak, even though the covalent bonds inside the molecule are strong.
由简单分子组成的物质熔点和沸点较低，因为分子间的分子间作用力很弱，尽管分子内部的共价键很强。
7. States of Matter and Changes of State | 物质状态与状态变化
The three main states of matter are solid, liquid, and gas. In solids, particles are closely packed in a regular arrangement and only vibrate. In liquids, particles are close but can move past each other. In gases, particles are far apart and move rapidly in all directions.
物质的三态是固态、液态和气态。固态中粒子紧密排列，位置固定，只能振动；液态中粒子相互靠近但能彼此滑动；气态中粒子相距很远，朝各个方向快速运动。
Key state changes:
重要的状态变化：
- Melting – solid to liquid. Imagine ice melting into water.
- 熔化 – 固态变为液态。想象冰化成水。
- Freezing – liquid to solid. Water turning into ice.
- 凝固 – 液态变为固态。水结成冰。
- Boiling / Evaporation – liquid to gas. Boiling occurs throughout the liquid; evaporation only at the surface.
- 沸腾 / 蒸发 – 液态变为气态。沸腾在液体各处发生，蒸发仅在表面。
- Condensation – gas to liquid. Water droplets on a cold window.
- 冷凝 – 气态变为液态。冷窗户上的水珠。
- Sublimation – solid directly to gas, like dry ice (solid CO₂) turning into gas.
- 升华 – 固态直接变为气态，如干冰（固态 CO₂）变为气体。
8. The Periodic Table: Groups and Periods | 元素周期表：族与周期
The periodic table organises elements in order of increasing atomic number. A period is a horizontal row; the period number tells you how many electron shells an atom has.
元素周期表是按原子序数递增排列的元素表格。周期是横排；周期数表示该元素原子具有的电子层数。
A group is a vertical column. Elements in the same group have the same number of valence electrons and therefore similar chemical properties. For example, Group 1 elements (alkali metals) all have one outer electron and are very reactive.
族是纵列。同族元素具有相同的价电子数，因此化学性质相似。例如，第 1 族（碱金属）都只有一个外层电子，都非常活泼。
Important group names to know: Group 1 – Alkali Metals, Group 7 – Halogens, Group 0 – Noble Gases.
需要记住的重要族名：第 1 族——碱金属，第 7 族——卤素，第 0 族——稀有气体。
9. Chemical Reactions and Equations | 化学反应与方程式
A chemical reaction is a process in which new substances are formed. The starting substances are called reactants; the new substances formed are called products.
化学反应 是生成新物质的过程。起始物质称为反应物，生成的新物质称为生成物。
on uses chemical formulas and must be balanced so that the total mass of reactants equals the total mass of products (conservation of mass).
文字表达式使用反应物和生成物的名称：镁 + 氧气 → 氧化镁。符号表达式使用化学式，且必须配平，以保证反应物的总质量等于生成物的总质量（质量守恒定律）。
Law of conservation of mass: matter is neither created nor destroyed in a chemical reaction, so the mass of the products equals the mass of the reactants.
质量守恒定律：化学反应中物质既不能被创造也不能被消灭，因此生成物的总质量等于反应物的总质量。
10. Acids, Bases and pH | 酸、碱与 pH
An acid is a substance that releases hydrogen ions (H⁺) in aqueous solution. Acids have a pH less than 7. Common laboratory acids include hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and nitric acid (HNO₃).
酸 是在水溶液中释放氢离子（H⁺）的物质，其 pH 小于 7。实验室常见酸包括盐酸（HCl）、硫酸（H₂SO₄）和硝酸（HNO₃）。
A base is a substance that can neutralise an acid. An alkali is a soluble base that releases hydroxide ions (OH⁻) in water. Alkalis have a pH greater than 7. Examples include sodium hydroxide (NaOH) and potassium hydroxide (KOH).
碱 是能中和酸的物质。可溶性碱 特指溶于水后释放氢氧根离子（OH⁻）的碱，其 pH 大于 7。例如氢氧化钠（NaOH）和氢氧化钾（KOH）。
action between an acid and a base, producing a salt and water: acid + base → salt + water.
中和反应是酸与碱反应生成盐和水的过程：酸 + 碱 → 盐 + 水。
The pH scale (0–14) measures how acidic or alkaline a solution is. pH 7 is neutral. Universal indicator turns different colours at different pH values.
pH 标度（0–14）用于衡量溶液的酸碱度，pH 7 为中性。通用指示剂在不同 pH 下呈现不同颜色。
11. Mixtures, Solutions and Separation Techniques | 混合物、溶液与分离技术
A mixture consists of two or more substances not chemically combined. Each substance keeps its own properties. Air is a mixture of gases; salty water is a mixture of salt and water.
混合物 由两种或以上未发生化学结合的物质组成，各组分保留自身的性质。空气是气体的混合物；盐水是盐和水的混合物。
A solution is a homogeneous mixture where a solute dissolves in a solvent. The solute is the dissolved substance; the solvent is the liquid doing the dissolving, often water.
溶液 是一种均一混合物，其中溶质溶解在溶剂里。溶质是被溶解的物质，溶剂是起溶解作用的液体，通常是水。
Key separation methods:
重要的分离方法：
- Filtration – separates an insoluble solid from a liquid (e.g., sand from water).
- 过滤 – 将不溶性固体与液体分离（如沙与水）。
- Distillation – separates a solvent from a solution by boiling and condensing the solvent (e.g., pure water from seawater).
- 蒸馏 – 通过蒸发并冷凝溶剂，使其从溶液中分离出来（如从海水中获得纯水）。
- Chromatography – separates dissolved substances based on their different solubilities (e.g., separating the colours in ink).
- 色谱法 – 根据不同物质在溶剂中溶解度的差异来分离溶解的物质（如分离墨水中的色素）。
12. Exothermic and Endothermic Reactions | 放热反应与吸热反应
An exothermic reaction transfers energy to the surroundings, usually as heat, making the surroundings warmer. Combustion and neutralisation are exothermic. Think 'Exo' as 'Exit' – energy exits the system.
放热反应 将能量（通常以热的形式）传递给周围环境，使环境温度升高。燃烧和中和反应是放热的。记法：“放”即“放出”能量。
An endothermic reaction takes in energy from the surroundings, causing the temperature to drop. Photosynthesis and thermal decomposition are endothermic. 'Endo' sounds like 'enter' – energy enters the system.
吸热反应 从周围环境吸收能量，导致温度下降。光合作用和热分解反应是吸热的。记法：“吸”即“吸收”能量。
Energy level diagrams show the difference in energy between reactants and products. In exothermic reactions, products have lower energy; in endothermic, products have higher energy.
能级图可以显示反应物与生成物之间的能量差。放热反应中生成物的能量更低；吸热反应中生成物的能量更高。
Published by TutorHao | Chemistry Revision Series | aleveler.com
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