📚 KS3 Edexcel Chemistry: Core Knowledge Review | KS3 Edexcel 化学：核心知识点梳理
Welcome to this KS3 Edexcel Chemistry revision guide. This article summarises the core concepts you need to master, from particles and atoms to chemical reactions and environmental chemistry. Use it to reinforce your understanding and prepare for assessments.
欢迎阅读 KS3 Edexcel 化学复习指南。本文归纳了从粒子与原子到化学反应和环境化学的核心知识点，助你巩固理解，备战评估。
1. Particle Theory and States of Matter | 粒子理论与物质状态
All matter is made up of tiny particles that are constantly moving. The arrangement and movement of these particles determine the state of matter.
所有物质都由不断运动的微小粒子组成。粒子的排列和运动方式决定了物质的状态。
In solids, particles vibrate around fixed positions, giving solids a definite shape and volume.
在固体中，粒子在固定位置振动，使固体具有固定的形状和体积。
In liquids, particles are close together but can slide past each other, so liquids have a fixed volume but take the shape of their container.
在液体中，粒子紧密排列但能相互滑动，因此液体有固定体积但形状随容器而变化。
In gases, particles are far apart and move rapidly in all directions, so gases have no fixed shape or volume and can be compressed.
在气体中，粒子相距很远且快速向各个方向运动，因此气体没有固定的形状和体积，可被压缩。
Changes of state, such as melting, boiling, condensing and freezing, involve energy transfer without changing the particles themselves.
状态变化（如熔化、沸腾、冷凝、凝固）涉及能量转移，但粒子本身不变。
Diffusion is the movement of particles from an area of high concentration to an area of low concentration, and it occurs faster in gases than in liquids.
扩散是粒子从高浓度区域向低浓度区域运动的过程，在气体中比在液体中发生得更快。
2. Atoms, Elements and Compounds | 原子、元素和化合物
An atom is the smallest part of an element that can exist. Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells.
原子是元素能存在的最小微粒。原子由含质子和中子的原子核以及核外分层排布的电子组成。
A substance that consists of only one type of atom is called an element. There are about 100 different elements shown in the periodic table.
只由一种原子组成的物质称为元素。元素周期表中列出了约100种不同的元素。
Compounds are substances formed when two or more elements chemically combine in fixed proportions. The properties of a compound are different from those of its constituent elements.
化合物是两种或多种元素以固定比例化合形成的物质。化合物的性质与其组成元素的性质不同。
A mixture contains two or more substances not chemically bonded together, so they can be separated by physical methods.
混合物含有两种或多种未通过化学键结合的物质，因此可通过物理方法分离。
Chemical symbols (e.g. O for oxygen, Fe for iron) represent elements, while chemical formulae (e.g. H₂O, CO₂) represent compounds.
化学符号（如 O 代表氧，Fe 代表铁）表示元素，化学式（如 H₂O、CO₂）表示化合物。
3. The Periodic Table | 元素周期表
The periodic table arranges elements in order of increasing atomic number (number of protons). Elements with similar properties are grouped into vertical columns called groups.
元素周期表按原子序数（质子数）递增排列。性质相似的元素被归入竖直列，称为族。
The horizontal rows are called periods. As you go across a period, elements change from metals on the left to non‑metals on the right.
水平行称为周期。沿周期从左到右，元素从金属逐渐变为非金属。
Group 1 contains the alkali metals, which are very reactive and have low densities. Group 7 contains the halogens, reactive non‑metals. Group 0 (or 8) contains the noble gases, which are unreactive.
第1族为碱金属，非常活泼且密度低；第7族为卤素，是活泼的非金属；第0族（或第8族）为稀有气体，化学性质稳定。
Key information you can read from each element’s box includes its atomic number, mass number and symbol. For example, carbon has atomic number 6 and mass number 12.
从每个元素的方框中可读出的关键信息包括原子序数、质量数和符号。例如，碳的原子序数为6，质量数为12。
The periodic table helps scientists predict the properties of elements and their reactions.
元素周期表帮助科学家预测元素的性质及其反应。
4. Chemical Reactions and Equations | 化学反应与方程式
In a chemical reaction, new substances are formed, and the change is usually irreversible. Signs of a reaction include colour change, temperature change, gas production and precipitate formation.
在化学反应中，会生成新物质，且变化通常不可逆。反应的迹象包括颜色变化、温度变化、气体生成和沉淀形成。
The law of conservation of mass states that the total mass of reactants equals the total mass of products. Atoms are rearranged, not created or destroyed.
质量守恒定律指出，反应物的总质量等于生成物的总质量。原子只是重新组合，既未生成也未消灭。
Word equations show the names of reactants and products, e.g. magnesium + oxygen → magnesium oxide.
文字方程式表示反应物和生成物的名称，例如：镁 + 氧 → 氧化镁。
Symbol equations use chemical formulae and must be balanced to obey the conservation of mass, e.g. 2Mg + O₂ → 2MgO.
符号方程式使用化学式，必须配平以遵守质量守恒，例如 2Mg + O₂ → 2MgO。
Common types of reactions include combustion, oxidation, thermal decomposition and neutralisation.
常见的反应类型包括燃烧、氧化、热分解和中和反应。
5. Acids, Alkalis and pH | 酸、碱与 pH
Acids are substances that release hydrogen ions (H⁺) in water. They have a pH less than 7 and turn blue litmus paper red. Examples include hydrochloric acid (HCl) and sulfuric acid (H₂SO₄).
酸是在水中释放氢离子（H⁺）的物质，其 pH 值小于 7，使蓝色石蕊试纸变红。例如盐酸（HCl）和硫酸（H₂SO₄）。
Alkalis are soluble bases that release hydroxide ions (OH⁻) in water. They have a pH greater than 7 and turn red litmus paper blue. Examples include sodium hydroxide (NaOH) and potassium hydroxide (KOH).
碱是可溶性碱，在水中释放氢氧根离子（OH⁻），其 pH 值大于 7，使红色石蕊试纸变蓝。例如氢氧化钠（NaOH）和氢氧化钾（KOH）。
The pH scale ranges from 0 to 14, with 7 being neutral. Universal indicator shows a range of colours at different pH values.
pH 标度范围为 0 至 14，7 为中性。通用指示剂在不同 pH 值下显示一系列颜色。
Neutralisation is the reaction between an acid and an alkali to form a salt and water: acid + alkali → salt + water.
中和反应是酸和碱反应生成盐和水：酸 + 碱 → 盐 + 水。
Everyday examples of neutralisation include using antacid tablets to relieve indigestion and treating acidic soil with lime.
日常生活中的中和反应实例包括用抗酸药缓解消化不良，用石灰处理酸性土壤。
6. Metals and Reactivity | 金属与反应性
Metals are typically shiny, good conductors of heat and electricity, malleable and ductile. Non‑metals are generally dull, brittle (if solid) and poor conductors.
金属通常有光泽，是热和电的良导体，具延展性。非金属通常暗淡、脆性（固体时），导热导电性差。
The reactivity series ranks metals from most to least reactive. At KS3, the order includes: potassium, sodium, calcium, magnesium, aluminium, zinc, iron, copper, silver, gold.
金属活动性顺序将金属从最活泼到最不活泼排列。KS3 阶段常见顺序为：钾、钠、钙、镁、铝、锌、铁、铜、银、金。
Reactive metals react with acids to produce a salt and hydrogen gas. For example: zinc + hydrochloric acid → zinc chloride + hydrogen.
活泼金属与酸反应生成盐和氢气。例如：锌 + 盐酸 → 氯化锌 + 氢气。
Metals react with oxygen to form metal oxides. This is an oxidation reaction. For example: magnesium + oxygen → magnesium oxide.
金属与氧反应生成金属氧化物，这是氧化反应。例如：镁 + 氧气 → 氧化镁。
The reactivity of a metal determines how it is extracted from its ore. Very unreactive metals like gold are found native, while reactive metals require electrolysis.
金属的活泼程度决定其从矿石中提取的方法。很不活泼的金属如金以游离态存在，而活泼金属需通过电解提取。
7. Separation Techniques | 分离技术
Mixtures can be separated by physical methods based on the different properties of their components. Common techniques include filtration, evaporation, distillation and chromatography.
利用混合物中各组分性质不同，可通过物理方法进行分离。常见技术包括过滤、蒸发、蒸馏和色谱法。
Filtration is used to separate an insoluble solid from a liquid, for example sand from water. The solid remains on the filter paper while the liquid passes through.
过滤用于分离不溶性固体和液体，例如从水中分离沙子。固体留在滤纸上，液体通过。
Evaporation removes the solvent from a solution, leaving the solid solute behind. It is suitable for obtaining a soluble salt from its solution.
蒸发去除溶液中的溶剂，留下固体溶质。适用于从溶液中获取可溶性盐。
Simple distillation separates a solvent from a solution by boiling and condensing. The pure solvent is collected as distillate.
简单蒸馏通过沸腾和冷凝将溶剂从溶液中分离出来，收集到的纯溶剂称为馏出液。
Chromatography separates dissolved substances that move at different speeds through a medium. It can be used to separate dyes in ink.
色谱法分离在介质中移动速度不同的溶解物质，可用于分离墨水中的染料。
8. Materials and Their Properties | 材料及其性质
Materials can be classified into natural and synthetic. Natural materials come from living things or the Earth, while synthetic materials are manufactured by chemical processes.
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