📚 Year 7 AQA Chemistry: High-Frequency Topics and Common Pitfalls | Year 7 AQA 化学：高频考点与易错题分析
Welcome to our focused revision guide for Year 7 AQA Chemistry. This article pulls together the most frequently tested topics and digs into the typical mistakes students make. By understanding these high-frequency ideas and where errors creep in, you can sharpen your knowledge and approach your exams with greater confidence.
欢迎阅读Year 7 AQA化学重点复习指南。本文汇集了最高频的考点，并深入分析学生常犯的错误。吃透这些核心概念，纠正常见误区，能帮助你巩固知识，更加自信地面对考试。
1. The Particle Model and States of Matter | 粒子模型与物质状态
The particle model is a cornerstone for explaining properties of solids, liquids and gases. Solid particles are tightly packed in a regular pattern and only vibrate in fixed positions. Liquid particles are still close but arranged randomly, so they can flow over one another. Gas particles are far apart, moving rapidly in all directions. When state changes occur—melting, freezing, evaporating, condensing, sublimation—energy is transferred, but the particles themselves do not change in size or number. A classic exam question asks you to draw particle diagrams for each state. A common mistake is drawing bigger particles for a gas or leaving unrealistic gaps in a solid.
粒子模型是解释固、液、气性质的基础。固体粒子紧密排列成规则图案，只在固定位置振动；液体粒子仍然紧密但随机分布，因此能够相互流动；气体粒子相距很远，朝各个方向快速运动。当发生状态变化（熔化、凝固、蒸发、凝结、升华）时，能量发生了转移，但粒子本身的大小和数量不变。经典考题常要求画出各状态的粒子图。常见错误是把气体粒子画得更大，或在固体中留出不现实的空隙。
When explaining properties such as why solids cannot be poured or why gases can be compressed, always link your answer to particle arrangement and energy. For example, a gas can be compressed because there is plenty of space between its particles. Remember that mass is conserved during a change of state—particle diagrams must contain the identical number of particles in each state.
解释性质（如固体为什么不能倾倒、气体为什么可以被压缩）时，一定要联系粒子的排列和能量。例如，气体可以被压缩是因为粒子之间有很大的空间。记住，状态变化时质量守恒——每种状态的粒子图中粒子数量必须相同。
2. Elements, Compounds and Mixtures | 元素、化合物和混合物
Distinguishing between elements, compounds and mixtures is a high-frequency assessment area. An element contains only one type of atom. A compound consists of two or more different types of atoms chemically bonded in a fixed ratio. A mixture consists of two or more substances (elements or compounds) that are not chemically joined and can be separated by physical techniques. Students often misclassify water as an element (it is a compound, H₂O) or air as a compound (it is a mixture of gases). When drawing particle models, a compound shows molecules of identical composition; a mixture shows different particles jumbled together.
区分元素、化合物和混合物是高频考点。元素只包含一种原子；化合物由两种或多种不同原子通过化学键结合而成，具有固定比例；混合物由两种或多种物质（元素或化合物）组成，没有化学结合，可通过物理方法分离。学生常将水误认为元素（它是化合物 H₂O），或者将空气当作化合物（它是气体混合物）。画粒子模型时，化合物展现出成分相同的分子，混合物则展示不同粒子混杂在一起。
Purity is another key idea: a pure substance has a sharp, specific melting and boiling point, while an impure mixture melts or boils over a range of temperatures. This concept is often explored in the context of separating mixtures. Make sure you can interpret particle diagrams and explain why a pure sample provides a single sharp melting point.
纯度是另一个关键概念：纯净物具有特定的固定熔点与沸点，而不纯的混合物在一个温度区间内熔化或沸腾。这个知识点常与混合物分离结合考查。确保你能读懂粒子图，并解释为什么纯净样品具有单一的固定熔点。
3. Common Element Symbols and the Periodic Table | 常见元素符号与周期表
You must be able to recall the names and symbols of the first 20 elements, plus a handful beyond that such as iron (Fe), copper (Cu), zinc (Zn) and lead (Pb). The rule of capitalisation is crucial: the first letter is always uppercase, the second lowercase if present. Writing ‘CO’ means carbon monoxide (a compound), whereas ‘Co’ is cobalt. ‘Na’ is sodium; ‘NA’ or ‘nA’ would lose marks. The periodic table is broadly divided into metals (left and middle) and non-metals (right). Year 7 questions often ask you to identify an element as a metal or non-metal based on its position or its properties such as conductivity and lustre.
你需要记住前20号元素以及铁（Fe）、铜（Cu）、锌（Zn）、铅（Pb）等常见元素的名称和符号。大小写规则至关重要：第一个字母大写，若有第二个字母则小写。写‘CO’表示一氧化碳（化合物），而‘Co’是钴。‘Na’代表钠，写成‘NA’或‘nA’会丢分。周期表大致分为金属（左边和中间）和非金属（右边）。7年级考题经常要求根据位置或导电性、光泽等性质判断某元素是金属还是非金属。
A typical exam question: “Give the name of the element with the symbol K.” Answer: potassium. “What is the symbol for calcium?” Answer: Ca, not CA. Also be prepared to link symbols to simple properties; for instance, copper is used in electrical wiring because it is a metal that conducts electricity and can be drawn into wires.
典型考题：“写出符号为K的元素名称。”答案：钾。“钙的元素符号是什么？”答案：Ca，而不是CA。还要能将符号与简单性质联系起来；例如，铜用于电线，因为它是金属，导电且可以拉成丝。
4. Naming Compounds and Chemical Formulae | 化合物命名与化学式
Simple compounds formed between a metal and a non-metal are named with the metal first and the non-metal ending in ‘-ide’, e.g. magnesium oxide (MgO), sodium chloride (NaCl). For two non-metals, the element that is more like a metal often goes first, but at Year 7 you mainly work with common compounds like carbon dioxide (CO₂) and water (H₂O). Chemical formulae use subscript numbers to show how many atoms of each element are present. A widespread mistake is writing NaCl₂ for sodium chloride, because students wrongly assume sodium has a 2+ charge. In reality, sodium forms Na⁺ and chloride forms Cl⁻, giving a 1:1 ratio.
金属与非金属形成的简单化合物，命名时金属在前，非金属以“-ide”结尾，如氧化镁（MgO）、氯化钠（NaCl）。两种非金属结合时，金属性较强的元素通常写在前面，不过7年级主要接触的是二氧化碳（CO₂）和水（H₂O）等常见化合物。化学式用下标数字表示每种元素的原子个数。一个普遍错误是把氯化钠写成NaCl₂，因为学生误以为钠带2+电荷。实际上钠是Na⁺，氯是Cl⁻，比例为1:1。
Exam tasks frequently ask you to count atoms in a formula like CaCO₃. The correct answer is 5 atoms: 1 calcium, 1 carbon, 3 oxygen. Be careful with brackets: magnesium hydroxide Mg(OH)₂ means one Mg and two OH groups (two O and two H atoms). Although brackets may not be tested in depth at Year 7, it is helpful to be aware.
考试常要求计算化学式中的原子个数，如CaCO₃中有5个原子：1个钙、1个碳、3个氧。注意括号：氢氧化镁 Mg(OH)₂表示1个Mg和2个OH基团（2个O和2个H）。虽然7年级不一定深入考查括号，但了解这些很有帮助。
5. Separating Mixtures: Filtration, Evaporation, Distillation, Chromatography | 分离混合物：过滤、蒸发、蒸馏、色谱
Filtration separates an insoluble solid from a liquid; for example, sand from water. Evaporation removes the solvent from a solution to leave a solid solute,
Published by TutorHao | Year 7 Chemistry Revision Series | aleveler.com
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