📚 Year 7 WJEC Chemistry: Core Knowledge Essentials | Year 7 WJEC 化学：核心知识点梳理
Welcome to your Year 7 WJEC Chemistry journey. In this article, we will systematically sort out the core knowledge you need to master, from the particle model to chemical reactions and key practical skills. Each section pairs an English explanation with its Chinese counterpart so that you can build both subject understanding and bilingual confidence.
欢迎来到 Year 7 WJEC 化学的学习之旅。本文将系统地梳理你需要掌握的核心知识点，从粒子模型到化学反应以及关键的实验技能。每个部分都以英中对照的方式呈现，帮助你在建立学科理解的同时提升双语能力。
1. The Particle Model of Matter | 物质的粒子模型
All substances are made of tiny particles. These particles are constantly moving, and the way they are arranged and move explains the properties of solids, liquids and gases.
所有物质都由微小的粒子组成。这些粒子不停地运动，它们的排列方式和运动状态决定了固体、液体和气体的性质。
In the particle model, particles in a solid are packed closely together in a regular pattern. They vibrate in fixed positions and cannot move around freely, which gives solids a definite shape and volume.
在粒子模型中，固体中的粒子紧密地排列成规则的图案。它们在固定的位置上振动，不能自由移动，因此固体有固定的形状和体积。
In a liquid, the particles are still close together but are arranged irregularly. They can slide past one another, allowing liquids to flow and take the shape of the bottom of their container, though they keep a constant volume.
在液体中，粒子仍然彼此靠近，但排列不规则。它们可以相互滑动，使液体能够流动并呈现容器底部的形状，同时保持恒定的体积。
In a gas, the particles are far apart and move randomly at high speed. Gases have no fixed shape or volume and will spread out to fill any container.
在气体中，粒子相距较远并且高速无规则运动。气体没有固定的形状和体积，会扩散并充满整个容器。
2. States of Matter and Changes of State | 物质状态与状态变化
The three common states of matter are solid, liquid and gas. Changing from one state to another involves adding or removing energy, usually as heat.
物质的三种常见状态是固态、液态和气态。从一种状态转变为另一种状态需要增加或减少能量，通常以热的形式。
Melting is the change from solid to liquid. It occurs at the melting point, and the particles gain enough energy to break free from their fixed positions but still stay close together.
熔化是从固态变为液态的过程，在熔点温度下发生，粒子获得足够的能量摆脱固定位置，但仍然彼此靠近。
Evaporation and boiling both change liquid to gas. Evaporation happens at the surface at any temperature, while boiling occurs throughout the liquid at the boiling point.
蒸发和沸腾都是液体变为气体的过程。蒸发可以在任何温度下在液体表面发生，而沸腾在沸点温度下在液体的内部和表面同时发生。
Condensation is the reverse process, where a gas turns into a liquid when it is cooled. The particles lose energy and move closer together. Freezing is the change from liquid to solid.
冷凝是相反的过程，气体冷却时变为液体。粒子失去能量并靠得更近。凝固是从液态变为固态的过程。
3. Atoms, Elements and the Periodic Table | 原子、元素与周期表
All matter is made up of atoms. An atom is the smallest particle of an element that can take part in a chemical reaction. An element is a substance made of only one type of atom.
所有物质都由原子组成。原子是参与化学反应的元素的最小粒子。元素是由同一种原子组成的纯物质。
There are about 118 different elements, and they are arranged in the periodic table. Each element has a unique chemical symbol, such as H for hydrogen, O for oxygen, and Fe for iron.
大约有 118 种不同的元素，它们排列在元素周期表中。每种元素都有一个独特的化学符号，例如 H 代表氢，O 代表氧，Fe 代表铁。
In the periodic table, metals are found on the left and in the centre, while non-metals are located on the right. Elements in the same vertical column, called a group, have similar chemical properties.
在周期表中，金属位于左侧和中间，非金属位于右侧。位于同一竖列（称为族）的元素具有相似的化学性质。
4. Compounds and Chemical Formulae | 化合物与化学式
When atoms of two or more different elements chemically combine, they form a compound. A compound has properties that are very different from the elements it is made from.
当两种或多种不同元素的原子通过化学方式结合时，就形成了化合物。化合物的性质与构成它的元素截然不同。
A chemical formula tells us the types and numbers of atoms in a compound. For example, water is H₂O, meaning each molecule contains two hydrogen atoms and one oxygen atom. Carbon dioxide is CO₂.
化学式表示化合物中原子的种类和数目。例如水是 H₂O，意味着每个分子含有两个氢原子和一个氧原子。二氧化碳是 CO₂。
Naming simple compounds often follows easy rules: when a metal reacts with a non-metal, the metal's name comes first, and the non-metal's name changes to end in '-ide', like sodium chloride (NaCl).
简单化合物的命名通常遵循规则：当金属与非金属反应时，金属的名称在前，非金属的名称改为以 “-ide” 结尾，例如 sodium chloride（氯化钠，NaCl）。
5. Mixtures and Separation Techniques | 混合物与分离技术
A mixture contains two or more different substances that are not chemically joined. The components in a mixture keep their own properties and can be separated by physical methods.
混合物包含两种或多种未通过化学方式结合的不同物质。混合物中的成分保持其原有的性质，并且可以通过物理方法进行分离。
Filtration is used to separate an insoluble solid from a liquid. The mixture is poured through filter paper; the liquid passes through, leaving the solid residue behind.
过滤用于将不溶性固体从液体中分离出来。将混合物倒入滤纸中，液体通过滤纸，固体残渣留在滤纸上。
Evaporation and crystallisation can obtain a soluble solid from a solution. By heating the solution gently, the solvent evaporates, leaving solid crystals behind. Chromatography separates dissolved coloured substances.
蒸发和结晶可以从溶液中得到可溶性固体。通过缓慢加热溶液，溶剂蒸发，留下固体晶体。色谱法用于分离溶解的有色物质。
Distillation is another powerful technique. Simple distillation separates a liquid from a solid solution by boiling and condensing, while fractional distillation can separate two or more liquids with different boiling points.
蒸馏是另一种有效的方法。简单蒸馏通过沸腾和冷凝将液体从固体溶液中分离出来，而分馏可以分离两种或多种沸点不同的液体。
6. Physical and Chemical Changes | 物理变化与化学变化
A physical change does not produce any new substances. Changes of state, dissolving, and breaking into pieces are all physical changes, and they are usually easy to reverse.
物理变化不会产生任何新物质。状态变化、溶解以及破碎成碎片都属于物理变化，通常容易逆转。
A chemical change, or chemical reaction, creates at least one new substance. Signs of a chemical reaction include colour change, temperature change, gas production (bubbles), or the formation of a precipitate.
化学变化（即化学反应）会产生至少一种新物质。化学反应的迹象包括颜色变化、温度变化、生成气体（气泡）或形成沉淀。
During a chemical reaction, atoms are rearranged. No atoms are lost or gained, so the total mass stays the same. This is the law of conservation of mass, which you will explore later.
在化学反应过程中，原子重新排列。原子不会凭空消失或增加，因此总质量保持不变。这就是质量守恒定律，你将在以后深入学习。
7. Introduction to Acids and Alkalis | 酸和碱的初步认识
Acids are a group of chemicals that taste sour and are corrosive. Common examples include citric acid in lemons and vinegar, which contains acetic acid. In the laboratory, we handle dilute hydrochloric acid safely.
酸是一类味道酸涩且具有腐蚀性的化学物质。常见的例子包括柠檬中的柠檬酸和含有醋酸的食醋。在实验室中，我们安全地使用稀盐酸。
Alkalis are soluble bases. They feel soapy and can also be corrosive. Household examples include sodium hydroxide in oven cleaners and ammonia in some cleaning products.
碱是可溶性的碱类物质。它们摸起来有滑腻感，也具有腐蚀性。常见家用例子包括烤箱清洁剂中的氢氧化钠和某些清洁产品中的氨。
and an alkali is: acid + alkali → salt + water. This is called a neutralisation reaction.
酸和碱反应的简单文字方程式为：酸 + 碱 → 盐 + 水。这被称为中和反应。
8. Neutralisation Reactions | 中和反应
Neutralisation happens when an acid and an alkali are mixed in just the right amounts to cancel each other's properties. The resulting solution is neither acidic nor alkaline but neutral, with a pH of about 7.
当酸和碱以恰好适当的比例混合，互相抵消彼此的性质时，就发生了中和反应。得到的溶液既不是酸性也不是碱性，而是中性的，pH 约为 7。
Everyday uses of neutralisation include treating indigestion with antacid tablets, which contain weak alkalis to neutralise excess stomach acid. Farmers also use lime (calcium oxide) to neutralise acidic soil.
中和反应在日常生活中的应用包括用抗酸药片治疗消化不良，这些药片含有弱碱性物质来中和过多的胃酸。农民也使用石灰（氧化钙）来中和酸性土壤。
In lab work, you can carry out neutralisation step by step using an indicator to monitor the pH change until the mixture turns neutral. Universal indicator shows a green colour at neutral.
在实验室中，你可以逐步进行中和，使用指示剂来监测 pH 值的变化，直到混合物变为中性。通用指示剂在中性时显示绿色。
9. The pH Scale and Indicators | pH 标度与指示剂
The pH scale measures how acidic or alkaline a solution is. It ranges from 0 to 14: values below 7 are acidic, exactly 7 is neutral, and values above 7 are alkaline. The lower the pH, the stronger the acid; the higher the pH, the stronger the alkali.
pH 标度用来衡量溶液的酸性或碱性程度。其范围从 0 到 14：低于 7 为酸性，等于 7 为中性，高于 7 为碱性。pH 值越低，酸性越强；pH 值越高，碱性越强。
Indicators are substances that change colour depending on the pH. Litmus paper turns red in acid and blue in alkali. Universal indicator gives a full spectrum of colours, making it easier to estimate pH values.
指示剂是能根据 pH 值改变颜色的物质。石蕊试纸在酸性条件下变红，在碱性条件下变蓝。通用指示剂呈现出全色系的颜色变化，更容易估计 pH 值。
You can also prepare a natural indicator using red cabbage. The juice turns pinkish in acids, green or blue in alkalis, and stays purple in neutral solutions.
你还可以用红甘蓝制备天然指示剂。这种汁液在酸中呈粉红色，在碱中呈绿色或蓝色，在中性溶液中保持紫色。
10. Metals and Non-metals | 金属与非金属
Elements can be broadly classified as metals or non-metals based on their physical and chemical properties. Most elements are metals.
根据物理和化学性质，元素可以大致分为金属和非金属。大多数元素是金属。
Typical metal properties include being shiny, good conductors of heat and electricity, malleable (can be hammered into sheets) and ductile (can be drawn into wires). Examples are iron, copper, aluminium and gold.
金属的典型性质包括：有光泽，是热和电的良导体，具有延展性（可被锤成薄片）和韧性（可拉成丝）。例子有铁、铜、铝和金。
Non-metals are generally dull, brittle when solid, and poor conductors of heat and electricity. Carbon, sulfur and oxygen are non-metals. Many non-metals are gases at room temperature.
非金属通常暗淡无光，固态时脆性大，是热和电的不良导体。碳、硫和氧是非金属。许多非金属在室温下是气体。
Metals react with oxygen to form metal oxides, which are often basic. Non-metals react with oxygen to form non-metal oxides, which are often acidic. This difference helps us understand the chemistry of our environment.
金属与氧气反应生成金属氧化物，这些氧化物通常是碱性的。非金属与氧气反应生成非金属氧化物，这些氧化物通常是酸性的。这种差异有助于我们理解环境的化学。
11. Earth's Atmosphere and Resources | 地球大气与资源
The Earth's atmosphere is a mixture of gases. The two main components are nitrogen (about 78%) and oxygen (about 21%). The remaining 1% includes argon, carbon dioxide and traces of other gases.
地球大气是一种气体混合物。两种主要成分是氮气（约 78%）和氧气（约 21%）。剩下的 1% 包括氩气、二氧化碳和痕量的其他气体。
Many useful materials come from the Earth's crust, including ores containing metals. We obtain metals by extracting them from ores through chemical reactions. For instance, iron is extracted from iron ore using carbon in a blast furnace.
许多有用的材料来自地壳，包括含有金属的矿石。我们通过化学反应从矿石中提取金属。例如，铁是通过在高炉中用碳还原铁矿石获得的。
Crude oil is another vital resource, formed from the remains of ancient sea creatures. It is a mixture of hydrocarbons and can be separated into useful fractions such as petrol and diesel by fractional distillation.
原油是另一种重要的资源，由古代海洋生物的遗骸形成。它是碳氢化合物的混合物，可以通过分馏分离成汽油和柴油等有用的馏分。
Limestone is a natural resource used to make building materials like cement and concrete. Understanding these resources helps us use them sustainably.
石灰石是一种天然资源，用于制造水泥和混凝土等建筑材料。了解这些资源有助于我们可持续地利用它们。
12. Key Skills: Scientific Enquiry and Safety | 关键技能：科学探究与安全
Working scientifically is at the heart of Year 7 Chemistry. You will learn to plan an investigation by identifying variables: the independent variable you change, the dependent variable you measure, and the control variables you keep the same.
以科学的方式开展探究是 Year 7 化学的核心。你将学习通过识别变量来规划调查：你改变的独立变量，你测量的因变量，以及你保持不变的控制变量。
Making careful observations and recording data in clear tables is essential. Always use proper units, such as grams for mass, degrees Celsius for temperature, and cm³ for volume. Results are often presented in bar charts or line graphs.
仔细观察并将数据记录在清晰的表格中至关重要。始终使用合适的单位，例如质量用克，温度用摄氏度，体积用立方厘米。结果常用条形图或折线图呈现。
Safety in the laboratory must come first. Always wear safety goggles, tie back long hair, and never taste chemicals. Know the hazard symbols for corrosive, flammable and toxic substances. When heating a test tube, point it away from yourself and others.
实验室安全必须放在首位。始终佩戴护目镜，扎起长发，绝不可尝化学药品。要认识腐蚀性、易燃和有毒物质的危险标志。加热试管时，管口要背离自己和他人。
Finally, evaluate your experiments by discussing whether your data is reliable and if any improvements could be made. Science is not just about knowing facts, but about asking questions and testing ideas.
最后，通过讨论数据是否可靠以及是否可以改进来评估你的实验。科学不仅仅是了解事实，更是提出问题和检验想法。
Published by TutorHao | Chemistry Revision Series | aleveler.com
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