📚 Year 7 Cambridge Chemistry: Core Concepts Review | Year 7 剑桥化学：核心知识点梳理
Welcome to this revision guide for Year 7 Cambridge Chemistry. The course introduces the fundamental concepts of matter, its changes, and the interactions between different substances. You will explore particle theory, learn to distinguish between elements, compounds and mixtures, and discover the world of acids and alkalis. This article will help you review the most important topics and prepare for your assessments.
欢迎阅读这篇 Year 7 剑桥化学复习指南。该课程介绍了物质、物质变化以及不同物质间相互作用的基本概念。你将探索粒子理论，学会区分元素、化合物和混合物，并发现酸和碱的世界。本文帮助你复习最重要的主题，为评估做好准备。
1. States of Matter and the Particle Model | 物质状态与粒子模型
All matter is made up of tiny particles. In solids, the particles are tightly packed in a regular pattern and can only vibrate in fixed positions. This explains why solids have a definite shape and volume.
所有物质都由微小粒子组成。在固体中，粒子紧密排列成规则模式，只能在固定位置振动。这解释了为什么固体有固定的形状和体积。
In liquids, the particles are still close together but can move past each other, so liquids take the shape of the container but have a fixed volume.
在液体中，粒子仍然紧密但可以彼此滑动，因此液体具有容器的形状但体积固定。
In gases, the particles are far apart and move randomly at high speeds. Gases have no fixed shape or volume and can be compressed easily.
在气体中，粒子相距很远且高速随机运动。气体没有固定形状或体积，容易被压缩。
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. It occurs in liquids and gases but not in solids because the particles are not free to move.
扩散是粒子从高浓度区域向低浓度区域运动的过程。它发生在液体和气体中而不在固体中，因为固体粒子不能自由移动。
2. Physical and Chemical Changes | 物理变化与化学变化
A physical change alters the form or appearance of a substance but does not create a new substance. Examples include melting, freezing, boiling, and dissolving. These changes are usually reversible.
物理变化改变物质的形式或外观，但不产生新物质。例如熔化、凝固、沸腾和溶解。这些变化通常是可逆的。
A chemical change results in the formation of one or more new substances with different properties. Chemical changes often involve energy changes, colour changes, gas production, or precipitate formation. They are usually irreversible.
化学变化会产生一种或多种性质不同的新物质。化学变化常伴随能量变化、颜色变化、气体产生或沉淀生成，通常不可逆。
Examples of chemical changes include rusting of iron, burning of magnesium, and the reaction between vinegar and baking soda.
化学变化的例子包括铁生锈、镁燃烧以及醋与小苏打的反应。
3. Elements, Compounds and Mixtures | 元素、化合物与混合物
An element is a pure substance that cannot be broken down into simpler substances by chemical means. Each element is made up of only one type of atom.
元素是不能通过化学方法分解成更简单物质的纯物质。每种元素只由一种原子组成。
A compound is a pure substance formed when two or more different elements chemically combine in fixed proportions. The properties of a compound are different from its constituent elements.
化合物是由两种或两种以上不同元素以固定比例化学结合而成的纯物质。化合物的性质不同于它的组成元素。
A mixture consists of two or more substances that are physically combined but not chemically bonded. Mixtures can be separated by physical methods, and the components retain their original properties.
混合物由两种或多种物理混合而非化学键合的物质组成。混合物可用物理方法分离，各组分保持原有的性质。
4. Atoms and the Periodic Table | 原子与元素周期表
An atom is the smallest particle of an element that retains the chemical properties of that element. Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells.
原子是元素最小的粒子，仍保持该元素的化学性质。原子由包含质子和中子的原子核以及核外电子层中的电子组成。
The periodic table organises all known elements according to their atomic number. Elements in the same group have similar chemical properties. Metals are found on the left, and non-metals on the right.
元素周期表根据原子序数排列所有已知元素。同一族的元素具有相似的化学性质。金属位于左侧，非金属位于右侧。
Year 7 students should be able to identify the first 20 elements and know that elements are represented by chemical symbols, such as H for hydrogen, O for oxygen, and Fe for iron.
Year 7 学生应能识别前 20 种元素，并知道元素用化学符号表示，例如氢的 H，氧的 O 和铁 Fe。
5. Metals and Non-metals | 金属与非金属
Elements can be classified as metals or non-metals based on their physical and chemical properties. Metals are typically shiny, good conductors of heat and electricity, malleable and ductile. Non-metals are usually dull, poor conductors, and brittle when solid.
根据物理和化学性质，元素可分为金属和非金属。金属通常有光泽，是热和电的良导体，具有延展性和韧性。非金属通常暗淡无光，导热导电性差，固态时易碎。
| Property (English) | 性质 (中文) |
|---|---|
| Shiny appearance | 有光泽 |
| Good conductors of heat and electricity | 热和电的良导体 |
| Malleable (can be hammered into sheets) | 有延展性（可锤打成薄片） |
| Ductile (can be drawn into wires) | 有韧性（可拉成细丝） |
| High melting and boiling points (most) | 熔点和沸点高（多数） |
| React with acids to produce hydrogen | 与酸反应产生氢气 |
Examples of metals include iron, copper, aluminium, and gold. Non-metals include oxygen, carbon, sulfur, and chlorine. Non-metals do not usually react with acids, and they often form acidic oxides when they burn.
金属的例子包括铁、铜、铝和金。非金属包括氧、碳、硫和氯。非金属通常不与酸反应，燃烧时常形成酸性氧化物。
6. Acids, Alkalis and Indicators | 酸、碱与指示剂
Acids are substances that have a sour taste and turn blue litmus paper red. Common laboratory acids include hydrochloric acid (HCl), sulfuric acid (H₂SO₄) and nitric acid (HNO₃).
酸是有酸味且能使蓝色石蕊试纸变红的物质。常见的实验室酸包括盐酸 (HCl)、硫酸 (H₂SO₄) 和硝酸 (HNO₃)。
Alkalis are soluble bases that feel soapy and turn red litmus paper blue. Examples include sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)₂).
碱
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