📚 Year 7 WJEC Chemistry: Summer Preparation and Bridging Course | Year 7 WJEC 化学：暑期预习与衔接课程
Starting Year 7 is an exciting step, and science opens the door to understanding the world around us. Chemistry is the study of substances, their properties, and how they change. This bridging guide will help you feel confident and curious before you walk into your first WJEC Chemistry lesson. You will explore matter, reactions, and the tiny particles that make up everything.
进入七年级是一个令人激动的阶段，科学为我们打开了理解周围世界的大门。化学是研究物质及其性质和变化规律的学科。这份衔接指南将帮助你在走进第一节 WJEC 化学课之前，建立信心并激发好奇心。你将探索物质、化学反应以及构成万物的微小粒子。
1. What is Chemistry? | 什么是化学？
Chemistry is the branch of science that investigates what materials are made of, their properties, and how they can be changed into new substances. In Year 7, you will begin to see that everything around you – the air you breathe, the water you drink, and your own body – is made of chemicals. Chemistry helps us make new medicines, clean water, and fuels that power vehicles.
化学是研究物质由什么构成、具有哪些性质以及如何转变成新物质的一门科学。在七年级，你将开始认识到周围的一切——你呼吸的空气、喝的水和自己的身体——都是由化学物质组成的。化学帮助我们制造新药物、净化水以及驱动车辆的燃料。
Think of chemists as detectives. They ask questions such as: Why does bread rise? Why do metals rust? How can we make a cake fluffy? Chemistry is full of experiments where you mix, heat, and observe, and the skills you learn will be useful in everyday life.
把化学家想象成侦探。他们会问：为什么面包会膨胀？为什么金属会生锈？我们如何让蛋糕变得松软？化学就是通过混合、加热、观察来进行的实验，你学到的技能在日常生活中也非常有用。
2. States of Matter | 物质的三种状态
Matter is any substance that has mass and takes up space. On Earth, matter commonly exists in three states: solid, liquid, and gas. Solids have a fixed shape and volume because their particles are tightly packed in a regular pattern. Liquids have a fixed volume but take the shape of their container, and their particles are close together but can slide past each other. Gases have no fixed shape or volume and spread out to fill any container; their particles are far apart and move rapidly in all directions.
物质是任何具有质量并占据空间的物体。在地球上，物质通常以三种状态存在：固体、液体和气体。固体具有固定的形状和体积，因为它们的粒子紧密排列成规则的结构。液体有固定的体积，但会取容器的形状，其粒子紧密但能彼此滑动。气体没有固定的形状和体积，会扩散并充满整个容器；其粒子相距很远，并朝各个方向快速运动。
Changes of state – melting, freezing, boiling, condensing, and sublimation – happen when a substance is heated or cooled. Heat energy makes particles move faster and overcome attractive forces, causing a solid to melt into a liquid or a liquid to boil into a gas. In the WJEC Year 7 course, you will learn to label these changes on a simple heating or cooling curve.
状态的变化——熔化、凝固、沸腾、冷凝和升华——发生在物质受热或冷却时。热能会让粒子运动加快，克服吸引力，使固体熔化成液体，或液体沸腾成气体。在 WJEC 七年级课程中，你将学会在简单的加热或冷却曲线上标注这些变化。
Solid ⇌ Liquid ⇌ Gas
3. The Particle Model | 粒子模型
The particle model is a way of thinking about how particles behave in solids, liquids, and gases. It helps explain why a solid holds its shape, why liquids flow, and why gases can be squeezed into a smaller volume. All substances are made of tiny particles that are constantly moving. In a solid, the particles vibrate in fixed positions. In a liquid, the particles are in contact but can move around each other. In a gas, the particles move freely and are far apart.
粒子模型是一种思考粒子在固体、液体和气体中行为的方式。它有助于解释为什么固体保持形状、液体能流动，以及气体能被压缩到更小的体积。所有物质都是由不断运动的微小粒子构成的。在固体中，粒子在固定位置振动。在液体中，粒子相互接触但可以彼此绕行。在气体中，粒子自由运动且相隔很远。
This model is powerful because it can also explain pressure, diffusion, and expansion. When a gas is heated, its particles gain energy and move faster, hitting the walls of their container harder – this increases pressure. Diffusion is the spreading of particles from an area of high concentration to an area of low concentration, and you can smell perfume across a room because perfume particles are diffusing through the air.
这个模型很强大，因为它还能解释压强、扩散和膨胀。当气体被加热时，其粒子获得能量并运动得更快，更强烈地撞击容器壁——这就增大了压强。扩散是粒子从高浓度区域向低浓度区域的散布，你能在房间的另一边闻到香水味，正是因为香水粒子在空气中扩散。
4. Elements, Compounds and Mixtures | 元素、化合物和混合物
Everything we see is made from elements, which are substances that contain only one type of atom. About 118 elements are known, and they are arranged in the Periodic Table. Each element has a symbol; for example, O for oxygen, Fe for iron, and C for carbon. Compounds are substances made from two or more different elements chemically bonded together. Water (H₂O) is a compound of hydrogen and oxygen. Mixtures are combinations of substances that are not chemically joined, like a salad or a jar of pebbles and sand.
我们看到的一切都是由元素组成的，元素是只包含一种原子的物质。已知约有118种元素，它们被排列在元素周期表中。每种元素都有一个符号；例如 O 代表氧，Fe 代表铁，C 代表碳。化合物是由两种或多种不同元素通过化学键结合而成的物质。水 (H₂O) 是氢和氧的化合物。混合物是没有通过化学方式结合在一起的物质组合，就像沙拉或一罐沙子和鹅卵石。
You can tell the difference by trying to separate them. A compound can only be broken down into its elements by chemical reactions, like using electrolysis to split water into hydrogen and oxygen. A mixture can be separated using physical methods such as filtering or evaporating. In Year 7, you will learn to draw simple particle diagrams showing elements as single circles, compounds as joined circles, and mixtures as different circles mixed but not bonded.
你可以通过尝试分离它们来区分。化合物只能通过化学反应分解成元素，比如用电解把水分解成氢气和氧气。混合物可以通过过滤、蒸发等物理方法分离。在七年级，你将学会绘制简单的粒子图，把元素画成单独的圆圈，化合物画成连接在一起的圆圈，混合物画成不同圆圈混在一起但没有连接。
5. Introducing Chemical Reactions | 化学反应的初步认识
A chemical reaction is a process where one or more substances (reactants) change into new substances (products). Signs of a chemical reaction include a colour change, a temperature change (the mixture gets hot or cold), a gas being produced (bubbles or fizzing), or a precipitate forming (a solid appearing from liquids). In a reaction, atoms rearrange themselves to make new bonds; no atoms are lost or made, which is why the mass stays the same in a closed system.
化学反应是一种过程，其中一种或多种物质（反应物）转变成新的物质（生成物）。化学反应的迹象包括颜色变化、温度变化（混合物变热或变冷）、产生气体（气泡或嘶嘶声）、或生成沉淀（液体中出现固体）。在反应中，原子重新排列形成新的键；原子既不会消失也不会凭空产生，这就是为什么在封闭系统中质量保持不变。
ll learn to write such equations using the names of chemicals and to recognise common reactions like burning (combustion) and the reaction of acids with carbonates. Always remember that a chemical change is different from a physical change, like melting or dissolving, because new substances are formed.
文字方程式是表示反应的简单方式。例如：甲烷 + 氧气 → 二氧化碳 + 水。你将学习使用化学物质的名称来书写这样的方程式，并识别常见的反应，如燃烧（可燃物与氧气反应）以及酸与碳酸盐的反应。始终要记住，化学变化不同于物理变化（如熔化或溶解），因为化学变化中会形成新物质。
6. Acids and Alkalis | 酸和碱
Acids are a group of chemicals that taste sour (but never taste chemicals in a lab!) and can be corrosive. Common laboratory acids include hydrochloric acid, sulfuric acid, and citric acid. Alkalis are substances that feel soapy and are the chemical opposite of acids; they can also be corrosive. Everyday alkalis include soap, bleach, and baking powder. In Year 7, you will learn to use indicators, which are substances that change colour in acids and alkalis. Litmus turns red in acid and blue in alkali. Universal indicator gives a full pH range from 1 (strong acid) to 14 (strong alkali), with 7 being neutral.
酸是一类化学品，尝起来酸（但在实验室里绝对不要尝任何化学品！）且可能具有腐蚀性。实验室常见的酸有盐酸、硫酸和柠檬酸。碱是一种摸起来滑腻的物质，是酸的化学对立面；它们同样可能具有腐蚀性。日常生活中的碱包括肥皂、漂白剂和发酵粉。在七年级，你将学习使用指示剂，指示剂是能在酸和碱中改变颜色的物质。石蕊试纸在酸中变红，在碱中变蓝。通用指示剂则能给出从 1（强酸）到 14（强碱）的完整 pH 范围，其中 7 为中性。
oxide → sodium chloride + water. Understanding pH helps us in gardening (soil pH), in health (stomach acid), and in safety (handling cleaning products). You will do simple practicals using well plates and indicator papers to investigate the pH of household items.
当酸与碱反应时，会发生中和反应，生成盐和水。例如：盐酸 + 氢氧化钠 → 氯化钠 + 水。理解 pH 有助于我们进行园艺（土壤 pH）、保健（胃酸）以及安全操作（处理清洁产品）。你将使用点滴板和 pH 试纸进行简单的实验操作，来探究家用物品的酸碱度。
7. Separation Techniques | 分离技术
Chemists often need to separate mixtures to obtain pure substances. You will meet several techniques in Year 7: filtration, evaporation, distillation, and chromatography. Filtration is used to separate an insoluble solid from a liquid, for example, sand from water, using filter paper in a funnel. The solid trapped on the paper is the residue, and the liquid that passes through is the filtrate.
化学家经常需要分离混合物以获得纯净物质。你将在七年级接触到几种技术：过滤、蒸发、蒸馏和色谱法。过滤用于将不溶性固体从液体中分离，比如用漏斗中的滤纸将沙子从水中分离。留在滤纸上的固体是残渣，透过滤纸的液体是滤液。
Evaporation is used to obtain a soluble solid from a solution by heating the solution until the liquid boils off, leaving solid crystals behind – common when getting salt from salty water. Distillation goes further by cooling the vapour to collect the pure liquid, and it is used to separate a solvent from a solution. Simple distillation can separate pure water from ink. Chromatography separates dissolved substances, like the different colours in black ink, as they travel up absorbent paper at different speeds. Each technique relies on differences in physical properties like boiling point, particle size, or solubility.
蒸发用于从溶液中获得可溶性固体，通过加热溶液使液体沸腾蒸发，留下固体晶体——常见于从盐水中获取食盐。蒸馏则更进一步，通过冷却蒸气来收集纯液体，用于从溶液中分离溶剂。简单蒸馏可以将纯水从墨水中分离出来。色谱法可以分离溶解的物质，例如黑色墨水中的不同颜色，因为它们以不同的速度在吸水纸上向上移动。每种技术都依赖于物理性质的差异，如沸点、颗粒大小或溶解度。
8. Combustion, Oxidation and Useful Reactions | 燃烧、氧化和有用的反应
Combustion is a chemical reaction in which a fuel reacts with oxygen and releases energy as heat and light. For complete combustion of a hydrocarbon, the products are carbon dioxide and water. However, if there is not enough oxygen, incomplete combustion can produce carbon monoxide (a toxic gas) and soot (carbon particles). In the WJEC curriculum, you explore the fire triangle: heat, fuel, and oxygen. Remove any side of the triangle, and the fire goes out. This is how fire extinguishers and fire blankets work.
燃烧是一种化学反应，燃料与氧气反应并以热和光的形式释放能量。对于碳氢化合物的完全燃烧，产物是二氧化碳和水。然而，如果氧气不足，不完全燃烧会产生一氧化碳（一种有毒气体）和烟灰（碳颗粒）。在 WJEC 课程中，你会探索火三角：热量、燃料和氧气。只要去掉三角形的任何一边，火就会熄灭。这就是灭火器和灭火毯的工作原理。
Oxidation is a broader term for reactions where a substance gains oxygen. Rusting is a slow oxidation of iron in the presence of both water and oxygen, forming hydrated iron(III) oxide. You will learn that rusting can be prevented by using barriers such as paint, oil, or plastic, or by sacrificial protection (attaching a more reactive metal like zinc). These ideas connect chemistry to real-world problems like protecting ships and bridges.
氧化是一个更广义的术语，指物质获得氧的反应。铁锈是铁在水和氧气同时存在下发生的缓慢氧化，生成水合氧化铁。你将学习到可以通过使用油漆、油或塑料等隔离层，或者通过牺牲性保护（附着一种更活泼的金属如锌）来防止生锈。这些概念将化学与现实世界的问题联系起来，如保护船舶和桥梁。
9. Working Safely in the Laboratory | 实验室安全操作
Before you carry out any experiment, you must know the safety rules. In Year 7, you will learn about common hazard symbols, such as flammable, corrosive, toxic, and irritant. Always wear safety goggles to protect your eyes, tie back long hair, and tuck in ties or loose clothing. Never eat or drink in the lab, and wash your hands after handling chemicals.
在进行任何实验之前，你必须了解安全规则。在七年级，你将学习常见的安全标志，如易燃、腐蚀性、有毒和刺激性。始终佩戴护目镜保护眼睛，把长发束起来，塞好领带或宽松衣物。不要在实验室里饮食，处理化学品后要洗手。
You will be taught how to use a Bunsen burner correctly. The air hole should be closed for a safety flame (yellow, cool) and opened for a roaring flame (blue, hot). When heating a test tube, point it away from yourself and others, and move it gently in and out of the flame. Knowing how to handle glassware and how to report spills or breakages is just as important as understanding the chemistry itself.
你还会学习如何正确使用本生灯。气孔关闭时产生安全火焰（黄色、低温），打开时产生强火焰（蓝色、高温）。加热试管时，要将管口朝向远离自己和他人，并轻轻地在火焰中来回移动。知道如何处理玻璃器皿以及如何报告溢出或破损，和理解化学知识本身同样重要。
10. Skills for Success: Observation, Recording and Tables | 成功的关键技能：观察、记录和表格
Chemistry is not just about knowing facts; it is also about how you think and work scientifically. You will develop skills in making careful observations – noticing colour changes, bubbling, temperature shifts, and smells (wafting, not sniffing directly). Always write down what you see, not what you expect to see. Good observations use precise language, such as “a white precipitate formed” rather than “it went cloudy.”
化学不仅仅是记住事实，还在于你如何科学地思考和工作。你将培养细致观察的能力——注意颜色变化、冒泡、温度变化和气味（用手扇闻，不可直接凑近闻）。始终记录你所看到的，而不是你预期看到的。好的观察会使用精确的语言，例如“生成了白色沉淀”而不是“它变浑浊了”。
You will learn to organise data in neatly drawn results tables, with column headings that include the quantity and the unit, for example “Temperature (°C)” or “Time (s).” Then you can plot graphs, often line graphs for continuous data or bar charts for categoric data. These skills will be assessed in every topic, so practising them over the summer, perhaps by keeping a simple kitchen science diary, will give you a head start.
你会学习将数据整理在绘制整齐的表格中，列标题要包括数量和单位，例如“温度 (°C)”或“时间 (s)”。然后你可以绘制图表，连续数据通常用折线图，分类数据用条形图。这些技能在每个主题中都会被评估，所以在暑假里练习，比如记一份简单的厨房科学日记，会让你走在前头。
11. Tips for Summer Preparation | 暑期准备小贴士
You do not need to memorise a textbook over the holidays. Instead, build curiosity. Watch a kettle boil and think about changes of state. Bake a cake and notice signs of a chemical reaction – bubbles from baking powder, a colour change in the crust. Try a simple separation: mix salt and sand, then add water and filter. These everyday experiences will make the classroom concepts feel familiar and enjoyable.
你不需要在假期里背教科书。相反，要培养好奇心。观察烧水壶，想想物质状态的变化。烤一个蛋糕，留意化学反应的迹象——泡打粉产生的气泡、面包皮的颜色变化。尝试简单的分离实验：把盐和沙子混合，加水然后过滤。这些日常体验会让课堂概念变得熟悉且有趣。
Review the particle model by drawing the particles in an ice cube, a glass of water, and steam. Learn the symbols of the first 20 elements of the Periodic Table as if they were a secret code – you will use them throughout secondary school. Practice writing word equations for simple burning or neutralisation reactions. A little pre-reading can make you feel ready and reduce any first-day nerves.
通过画冰块、一杯水和蒸汽中的粒子来复习粒子模型。把元素周期表前20个元素的符号当成秘密代码来学习——你在整个中学阶段都会用到它们。练习书写简单的燃烧或中和反应的文字方程式。一点预习阅读就能让你感到准备充分，减少开学第一天的紧张。
12. Key Vocabulary to Learn | 需要掌握的关键词汇
Building a strong scientific vocabulary will help you follow lessons and express your ideas. Create flashcards for words like: element, compound, mixture, atom, molecule, particle, diffusion, solution, solvent, solute, soluble, insoluble, filtrate, residue, pH, indicator, neutralisation, combustion, oxidation, reactant, product, and exothermic (releases heat).
建立扎实的科学词汇量将帮助你跟上课程并表达自己的想法。为以下词语制作闪卡：元素、化合物、混合物、原子、分子、粒子、扩散、溶液、溶剂、溶质、可溶的、不可溶的、滤液、残渣、酸碱度、指示剂、中和、燃烧、氧化、反应物、生成物，以及放热（释放热量）。
A good way to learn is to group related words. For example, you can group “solute + solvent = solution” and “filtrate and residue” from filtration. Use each new word in a sentence: “The indicator changed colour because the solution was acidic.” e terms, the more confident you will feel in discussions and in writing up investigations.
一个好办法是把相关的词语归类。例如，你可以将“溶质+溶剂=溶液”归为一组，以及过滤中的“滤液和残渣”。用每个新词造句：“指示剂变了颜色，因为溶液是酸性的。”你越早熟悉这些术语，在讨论和撰写实验报告时就会越自信。
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