📚 Year 7 AQA Chemistry Core Knowledge Summary | Year 7 AQA 化学核心知识点梳理
Welcome to your Year 7 AQA Chemistry revision guide. This article brings together every core idea from the course, explaining them clearly so you can build a strong foundation. Whether you are reviewing the particle model, exploring elements and compounds, or learning about acids and alkalis, you will find the essential knowledge paired with simple explanations.
欢迎阅读Year 7 AQA化学复习指南。本文梳理了课程的所有核心概念，用清晰的方式帮助你打下扎实基础。无论你是在复习粒子模型、探索元素与化合物，还是学习酸和碱，这些基础知识都将搭配简洁的解释，让你轻松掌握。
1. Matter and the Particle Model | 物质与粒子模型
All matter is made of tiny particles. These particles can be atoms, molecules or ions, depending on the substance. The particle model helps us explain the behaviour of solids, liquids and gases.
所有物质都由微小粒子组成。这些粒子可能是原子、分子或离子，具体取决于物质种类。粒子模型帮助我们解释固体、液体和气体的行为。
There are spaces between particles, even in solids. In a solid, the particles are packed closely together in a regular arrangement. In liquids, they are close but can move past each other. In gases, the particles are far apart and move rapidly in all directions.
粒子之间都存在空隙，即使在固体中也不例外。固体中粒子紧密排列，呈规则的几何结构；液体中粒子依然很近，但可以相互滑动；气体中粒子相距很远，向各个方向快速运动。
Particles are always moving. The higher the temperature, the more kinetic energy they have, and the faster they move. This explains why substances expand when heated and contract when cooled.
粒子始终在运动。温度越高，它们的动能越大，运动也就越快。这解释了为什么物质会热胀冷缩。
2. States of Matter | 物质的三态
There are three common states of matter on Earth: solid, liquid and gas. Each state has distinct properties that can be explained by the particle model.
地球上物质常见的三种状态是固态、液态和气态。每一种状态都有独特的性质，可以用粒子模型加以解释。
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Shape | Fixed | Takes shape of container | No fixed shape |
| Volume | Fixed | Fixed | Fills the container |
| Particle arrangement | Regular, close together | Random, close together | Random, far apart |
| Movement | Vibrate in fixed positions | Move past each other | Move quickly in all directions |
The table shows that a solid keeps its own shape because particles are held in a regular pattern and can only vibrate. A liquid has a fixed volume but flows to match the shape of the container. A gas has no fixed shape or volume, because its particles move freely and spread out.
上表显示，固体能保持自身形状是因为粒子被固定在规则排列中，仅能振动。液体有固定体积，但因粒子可以相互滑动而能流动并呈容器底部形状。气体既无固定形状也无固定体积，其粒子自由运动并充满整个容器。
Changes of state, such as melting, freezing, boiling and condensation, can be understood as changes in the energy and arrangement of particles rather than changes in the particles themselves.
状态变化，如熔化、凝固、沸腾和冷凝，可以理解为粒子能量和排列方式的改变，而非粒子本身发生了改变。
3. Atoms and Elements | 原子与元素
An atom is the smallest particle of an element that can exist on its own. Every atom has a tiny nucleus containing protons and neutrons, surrounded by electrons.
原子是元素能独立存在的最小粒子。每个原子都有一个微小的原子核，由质子和中子组成，核外有电子围绕运转。
An element is a pure substance made of only one type of atom. All known elements are listed on the periodic table, and each one is represented by a unique chemical symbol, such as H for hydrogen, O for oxygen, and Fe for iron.
元素是由同一种原子组成的纯净物。所有已知元素都列在元素周期表中，每种元素都有一个独特的化学符号，例如氢(H)、氧(O)、铁(Fe)。
Some elements exist as single atoms, but many consist of molecules made of two or more atoms of the same element. For example, oxygen gas is O₂ and nitrogen gas is N₂.
有些元素以单原子形式存在，但许多元素由同种元素的两个或多个原子构成的分子组成。例如，氧气是O₂，氮气是N₂。
There are about 100 elements found in nature. Most of the Earth's mass is made of just a few elements, such as oxygen, silicon, aluminium and iron.
自然界中大约存在100种元素。地球质量的大部分仅由少数几种元素构成，如氧、硅、铝和铁。
4. The Periodic Table | 元素周期表
The periodic table arranges all elements in order of increasing atomic number (the number of protons). Elements are placed in rows called periods and columns called groups.
元素周期表按原子序数（质子数）递增的顺序排列所有元素。元素被排列在称为周期的横行和称为族的纵列中。
Elements in the same group have similar chemical properties because they have the same number of electrons in their outer shell. For example, Group 1 elements are all very reactive metals, while Group 0 (noble gases) are unreactive.
同一族元素具有相似的化学性质，因为它们最外层电子数相同。例如，第1族元素都是非常活泼的金属，而第0族（稀有气体）则很不活泼。
The table is divided into metals on the left and non‑metals on the right. A zig-zag line separates them. Metals are shiny, conduct electricity and are malleable, whereas non‑metals are often dull, brittle and poor conductors.
周期表左边是金属，右边是非金属，中间有一条锯齿形分界线。金属有光泽、能导电、具有延展性；而非金属通常暗淡、脆性且导电性差。
5. Compounds and Their Formation | 化合物及其形成
A compound is a pure substance formed when two or more different elements are chemically bonded together. The properties of a compound are different from the properties of the elements that make it.
化合物是由两种或多种不同元素通过化学键结合而成的纯净物。化合物的性质与其组成元素的性质不同。
Compounds have a fixed composition. For instance, water (H₂O) always contains two hydrogen atoms and one oxygen atom. Carbon dioxide (CO₂) always has one carbon atom and two oxygen atoms.
化合物有固定的组成。例如，水(H₂O)总是由两个氢原子和一个氧原子构成；二氧化碳(CO₂)总是由一个碳原子和两个氧原子构成。
Molecules of compounds are held together by chemical bonds, such as ionic or covalent bonds. Simple molecular compounds like water and carbon dioxide have low melting and boiling points, while giant ionic compounds like sodium chloride (NaCl) have high melting points.
化合物分子通过化学键（如离子键或共价键）结合在一起。像水和二氧化碳这样的简单分子化合物熔点和沸点较低，而像氯化钠(NaCl)这样的巨型离子化合物则熔点较高。
6. Mixtures and Separation | 混合物及其分离
A mixture consists of two or more substances that are physically combined but not chemically bonded. The components keep their original properties and can be present in any proportion.
混合物由两种或多种通过物理方式混合、未发生化学结合的物质组成。各组分保持原有性质，并且可以任意比例存在。
Common examples of mixtures include air (a mixture of gases), seawater (salt dissolved in water) and sand mixed with pebbles. Unlike compounds, mixtures can usually be separated by physical methods.
常见的混合物包括空气（气体混合物）、海水（盐溶于水）以及沙子和小石子的混合物。与化合物不同，混合物通常可以通过物理方法分离。
Different separation techniques are used depending on the properties of the components. Filtering separates an insoluble solid from a liquid. Evaporation and crystallisation obtain a dissolved solid from a solution. Simple distillation separates a solvent from a solution using differences in boiling points. Chromatography separates dissolved coloured substances.
根据组分性质不同，可采用不同的分离方法。过滤用于分离不溶性固体与液体；蒸发和结晶用于从溶液中得到溶解的固体；简单蒸馏利用沸点差异从溶液中分离出溶剂；色谱法用于分离溶解的有色物质。
7. Chemical Reactions | 化学反应
A chemical reaction involves the rearrangement of atoms to form new substances. The starting materials are called reactants, and the new substances are called products. No atoms are created or destroyed – this is the law of conservation of mass.
化学反应涉及原子重新排列形成新物质。起初的物质称为反应物，生成的新物质称为产物。反应过程中原子不会凭空产生或消失——这就是质量守恒定律。
Signs that a chemical reaction has taken place include colour change, formation of a precipitate (solid), release of gas bubbles, and energy changes (such as a rise or fall in temperature).
表明发生了化学反应的标志包括颜色变化、生成沉淀（固体）、产生气泡以及能量变化（如温度升高或降低）。
We can sum up reactions using word equations. For example, when magnesium burns in oxygen, the equation is:
我们可以用文字表达式概括化学反应。例如，镁在氧气中燃烧的表达式为：
magnesium + oxygen → magnesium oxide
Exothermic reactions release heat to the surroundings (e.g., burning fuels), while endothermic reactions absorb heat (e.g., thermal decomposition).
放热反应向周围环境释放热量（如燃料燃烧），吸热反应则吸收热量（如热分解）。
8. Acids and Alkalis | 酸和碱
An acid is a substance that releases H⁺ ions when dissolved in water. Acids have a sour taste (though you should never taste chemicals in the lab) and turn blue litmus paper red. Common laboratory acids include hydrochloric acid (HCl), sulfuric acid (H₂SO₄) and nitric acid (HNO₃).
酸是溶于水时会释放H⁺离子的物质。酸有酸味（但绝不能在实验室品尝化学品），能使蓝色石蕊试纸变红。实验室常见的酸包括盐酸(HCl)、硫酸(H₂SO₄)和硝酸(HNO₃)。
An alkali is a soluble base that releases OH⁻ ions in water. Alkalis have a bitter taste and feel slippery; they turn red litmus paper blue. Examples include sodium hydroxide (NaOH) and potassium hydroxide (KOH).
碱是可溶性碱，溶于水时释放OH⁻离子。碱有苦味且手感滑腻，能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 measures how acidic or alkaline a solution is. Acids have a pH less than 7; neutral solutions (like pure water) have a pH of 7; alkalis have a pH greater than 7. Universal indicator shows a range of colours from red for strong acids to purple for strong alkalis.
pH标度衡量溶液的酸碱性。酸的pH小于7，中性溶液（如纯水）的pH等于7，碱的pH大于7。万能指示剂能显示从强酸的红色到强碱的紫色之间的各种颜色。
When an acid reacts with an alkali, a neutralisation reaction occurs, producing a salt and water:
当酸与碱反应时，发生中和反应，生成盐和水：
hydrochloric acid + sodium hydroxide → sodium chloride + water
9. Earth's Structure and Atmosphere | 地球的结构与大气层
The Earth is made up of several layers: the inner core, outer core, mantle and crust. The crust is the thin, solid outermost layer where we live. Below it, the mantle is composed of semi‑solid rock that moves slowly, driving plate tectonics.
地球由几层结构组成：内核、外核、地幔和地壳。地壳是我们所生活的薄而坚实的最外层。地壳之下，地幔由缓慢流动的半固态岩石组成，推动着板块运动。
The atmosphere surrounding Earth is a mixture of gases, mainly nitrogen (about 78%) and oxygen (about 21%). The remaining 1% includes argon, carbon dioxide and trace gases. This composition is essential for life and influences our climate.
环绕地球的大气层是气体的混合物，主要成分是氮气（约78%）和氧气（约21%）。剩下的1%包括氩气、二氧化碳和微量气体。这一组成对生命至关重要，并影响着我们的气候。
Carbon dioxide in the atmosphere is absorbed by plants during photosynthesis and returned to the air through respiration, combustion of fossil fuels, and decomposition. The balance of these processes maintains a stable level of CO₂, though human activities are increasing it, leading to global warming.
大气中的二氧化碳被植物通过光合作用吸收，又通过呼吸作用、化石燃料燃烧和分解作用回到空气中。这些过程的平衡维持着稳定的CO₂水平，但人类活动正在增加其浓度，导致全球变暖。
10. Practical Skills and Safety | 实验技能与安全
Working safely in the laboratory is a key part of Year 7 chemistry. You must always wear safety goggles and a lab coat, tie back long hair, and never eat or drink in the lab. Read hazard labels carefully and use the correct amounts of chemicals.
在实验室中安全工作Year 7化学的关键组成部分。你必须始终佩戴护目镜和实验服，将长发束起，不要在实验室饮食。仔细阅读危险标签，并使用正确剂量的化学品。
Using a Bunsen burner requires care: use a yellow safety flame when not heating and allow the burner to cool before touching it. Safety flames are visible and cooler, while a blue roaring flame provides intense heat.
使用本生灯时需小心：不加热时使用黄色的安全火焰，并等它冷却后再触碰。安全火焰可见且温度较低，而蓝色咆哮火焰可提供剧烈加热。
When measuring and recording results, always use appropriate units, such as cm³ for volume, g for mass, and °C for temperature. Record data accurately in a table and repeat measurements to improve reliability. Identify the independent, dependent and control variables in any experiment you plan.
测量和记录结果时，务必使用合适的单位，如体积用cm³，质量用g，温度用℃。准确记录数据于表格中，并重复测量以提高可靠性。在计划实验时，你能识别出自变量、因变量和控制变量。
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