📚 Year 8 WJEC Chemistry: Key Terminology Memorisation Guide | Year 8 WJEC 化学：关键术语速记指南
Mastering scientific vocabulary is the secret to feeling confident in every chemistry lesson and exam. This guide unpacks all the essential Year 8 WJEC terms, pairing each one with a clear definition, a practical example, and a memory trick that makes the word stick. By the end, you will be able to decode chemical language and use it like a pro.
掌握科学词汇是让你在每节化学课和考试中都充满自信的秘诀。这份指南拆解了所有 Year 8 WJEC 的核心术语，为每个词配上了清晰的定义、实用的例子和能让单词牢牢记住的记忆技巧。读完它，你就能像行家一样破译和使用化学语言了。
1. States of Matter | 物质状态
All substances are made of tiny particles. The arrangement and energy of these particles explain why a material appears as a solid, liquid, or gas.
所有物质都由微小粒子组成。粒子的排列方式和能量大小解释了一种材料为何呈现为固态、液态或气态。
Solid: Particles are packed in a fixed, regular pattern and can only vibrate on the spot. This gives a solid a definite shape and a definite volume.
固体：粒子以固定的规则图案紧密排列，只能在原地振动。这让固体具有确定的形状和确定的体积。
Liquid: Particles are still touching but are arranged randomly and can slide past one another. A liquid has a fixed volume but takes the shape of its container.
液体：粒子仍然相互接触，但排列无序，可以彼此滑动。液体有固定的体积，但形状随容器变化。
Gas: Particles are far apart, move rapidly in all directions, and only interact when they collide. A gas has no fixed shape or volume and will spread to fill any container.
气体：粒子相距很远，朝各个方向快速运动，只在碰撞时相互作用。气体没有固定的形状或体积，会扩散并充满任何容器。
Melting is solid → liquid; freezing is liquid → solid. Boiling and evaporation turn liquid → gas; condensation turns gas → liquid. Sublimation is a direct change from solid to gas, bypassing the liquid stage (e.g. solid carbon dioxide, dry ice).
熔化是固态→液态；凝固是液态→固态。沸腾和蒸发让液态→气态；冷凝让气态→液态。升华是从固态直接变成气态，跳过液态阶段（如固体二氧化碳，干冰）。
2. Atoms and Elements | 原子与元素
An atom is the smallest particle of an element that can take part in a chemical reaction. Everything around you is built from about 100 different types of atom.
原子是能参与化学反应的元素的最小粒子。你周围的一切都由大约 100 种不同类型的原子构建而成。
An element is a pure substance made of only one type of atom. Each element is listed on the Periodic Table and represented by a chemical symbol, such as O for oxygen, Fe for iron, and Na for sodium.
元素是仅由一种原子组成的纯净物。每种元素都列在元素周期表中，用一个化学符号表示，例如 O 代表氧，Fe 代表铁，Na 代表钠。
Every atom has a central nucleus containing protons (positive charge) and neutrons (no charge). Tiny electrons (negative charge) orbit the nucleus in shells.
每个原子都有一个位于中心的原子核，里面有质子（带正电）和中子（不带电）。微小的电子（带负电）在核外的电子层上运动。
Memory tip: Think of the nucleus as the sun and electrons as planets circling it. The atomic number tells you the number of protons, which is unique to every element.
记忆提示：把原子核想象成太阳，电子就像绕它运行的行星。原子序数表示质子数，每个元素都独一无二。
3. Compounds and Mixtures | 化合物与混合物
A compound is a substance formed when two or more different elements are chemically bonded together. The properties of a compound are completely different from the elements that make it. For instance, sodium is a reactive metal and chlorine is a poisonous gas, but together they form sodium chloride – table salt.
化合物是由两种或更多不同元素通过化学键结合在一起形成的物质。化合物的性质与组成它的元素完全不同。比如，钠是一种活泼金属，氯是一种有毒气体，但它们结合在一起形成氯化钠——食盐。
A mixture consists of two or more substances (elements or compounds) that are physically mixed but not chemically joined. Air is a mixture of nitrogen, oxygen, carbon dioxide and other gases. The components keep their own properties and can be separated by physical means.
混合物由两种或多种物质（元素或化合物）物理混合而成，它们并没有通过化学键结合。空气就是氮气、氧气、二氧化碳和其他气体的混合物。各组分保持原有性质，可以通过物理方法分离。
Key difference: Compounds require chemical reactions to break apart; mixtures can be separated using techniques like filtration or distillation. The formula of a compound, like H₂O, shows the exact ratio of atoms; a mixture has no fixed formula.
关键区别：化合物需要通过化学反应才能分解；混合物可以用过滤或蒸馏等技术分离。化合物的化学式（如 H₂O）显示了精确的原子比例；混合物没有固定的化学式。
4. Physical and Chemical Changes | 物理变化与化学变化
A physical change alters the appearance or state of a substance but does not create a new substance. Examples include melting ice, tearing paper, and dissolving sugar in water. These changes are usually easy to reverse.
物理变化会改变物质的外观或状态，但不会生成新物质。例子包括冰融化、撕纸和糖溶于水。这些变化通常很容易逆转。
A chemical change (or chemical reaction) produces at least one new substance with different properties from the reactants. Signs of a chemical reaction include a colour change, a gas being released (bubbles), a precipitate (solid) forming, or a noticeable temperature change.
化学变化（或化学反应）会产生至少一种与反应物性质不同的新物质。化学反应的标志包括颜色改变、有气体放出（气泡）、生成沉淀（固体）或明显的温度变化。
In a chemical change, it is often difficult or impossible to get the original substances back simply by reversing the conditions. Iron rusting and baking a cake are both examples of chemical changes.
在化学变化中，通常很难或不可能仅通过逆转条件就得到原来的物质。铁生锈和烤蛋糕都是化学变化的例子。
5. Chemical Reactions | 化学反应
A chemical reaction always involves reactants (starting substances) turning into products (new substances). We write a word equation to show the change: methane + oxygen → carbon dioxide + water.
化学反应总是涉及反应物（起始物质）转变为生成物（新物质）。我们用文字表达式来表示这一变化：甲烷 + 氧气 → 二氧化碳 + 水。
The law of conservation of mass says that atoms are never created or destroyed in a chemical reaction. The total mass of the reactants always equals the total mass of the products. That is why we must balance chemical equations later on.
质量守恒定律告诉我们，原子在化学反应中既不会被创造也不会被消灭。反应物的总质量总是等于生成物的总质量。这就是我们以后必须配平化学方程式的原因。
Some reactions release heat energy to the surroundings – they are called exothermic. Others absorb heat, making their container feel colder – these are endothermic. A simple hand-warmer uses an exothermic reaction, while an ice pack often uses an endothermic one.
有些反应会向周围放出热量，称为放热反应。另一些反应会吸收热量，使容器变冷，称为吸热反应。简易暖手宝利用的是放热反应，而冰袋通常利用吸热反应。
6. Acids and Alkalis | 酸与碱
An acid is a substance that releases hydrogen ions (H⁺) when dissolved in water. They taste sour and can be corrosive. Common laboratory acids include hydrochloric acid, sulfuric acid, and nitric acid. Citrus fruits contain citric acid.
酸是一种溶于水时释放氢离子（H⁺）的物质。它们尝起来是酸的，可能有腐蚀性。实验室常见的酸有盐酸、硫酸和硝酸。柑橘类水果含有柠檬酸。
An alkali is a soluble base that releases hydroxide ions (OH⁻) in water. Alkalis feel soapy and are also corrosive. Examples include sodium hydroxide (in drain cleaner) and calcium hydroxide (limewater). Bases are substances that can neutralise acids; alkalis are bases that dissolve in water.
碱是一种可溶性的、在水中释放氢氧根离子（OH⁻）的物质。碱有滑腻感，也具有腐蚀性。例子包括氢氧化钠（用于下水道清洁剂）和氢氧化钙（石灰水）。碱是能中和酸的物质；而可溶性碱就是碱。
The pH scale (0–14) measures how acidic or alkaline a solution is. Values below 7 are acidic, 7 is neutral (pure water), and above 7 are alkaline. Indicators n an acid reacts with an alkali to produce a salt and water: acid + alkali → salt + water.
pH 标度（0–14）用来衡量溶液的酸碱度。pH 小于 7 为酸性，等于 7 为中性（纯水），大于 7 为碱性。指示剂，如石蕊试纸或万用指示剂，会变色以指示 pH 值。酸和碱反应生成盐和水的过程叫做中和：酸 + 碱 → 盐 + 水。
7. The Periodic Table | 元素周期表
The Periodic Table organises all known elements in order of increasing atomic number. The vertical columns are called groups; elements in the same group have similar chemical properties because they have the same number of electrons in their outer shell.
元素周期表按原子序数递增的顺序排列所有已知元素。纵列称为族；同一族的元素化学性质相似，因为它们最外层电子数相同。
Horizontal rows are called periods. As you move across a period, the elements change from metals on the left to non-metals on the right. Most elements are metals – they are shiny, good conductors of heat and electricity, malleable and ductile. Non-metals are generally dull, brittle, and poor conductors.
横行称为周期。在同一周期中，元素从左边的金属逐渐变为右边的非金属。大多数元素是金属——它们有光泽，是热和电的良导体，具有延展性。非金属通常暗淡、易碎，是热和电的不良导体。
Dmitri Mendeleev first arranged elements by atomic mass and left gaps for undiscovered elements, predicting their properties. Today we arrange by atomic number. A memory trick for the first 20: 'Harry He Likes Beer But Could Not Obtain Food' – H, He, Li, Be, B, C, N, O, F.
德米特里·门捷列夫最早按原子量排列元素，并为尚未发现的元素留出空位，预测了它们的性质。今天我们按原子序数排列。前 20 个元素的记忆技巧：'Happy Henry Likes Beer But Could Not Obtain Four Nuts' – H, He, Li, Be, B, C, N, O, F, Ne...
8. Separation Techniques | 分离技术
Filtration separates an insoluble solid from a liquid using filter paper. The solid stays on the paper (residue) and the liquid passes through (filtrate). It is used to separate sand from water.
过滤利用滤纸将不溶性固体与液体分离。固体留在滤纸上（残渣），液体通过（滤液）。它用于分离沙子与水。
Evaporation removes a soluble solid from a solution by heating until the liquid turns into vapour, leaving the solid behind. Crystallisation is a gentler technique: the solution is heated to form a saturated solution, then cooled so large crystals form.
蒸发通过加热将溶液中的可溶性固体分离出来，液体变成蒸汽，固体残留下来。结晶是一种更温和的技术：将溶液加热形成饱和溶液，然后冷却，析出大晶体。
Distillation is used to separate a solvent from a solution or to separate liquids with different boiling points. The liquid boils, the vapour is cooled and condensed back into a liquid, and collected. Chromatography separates different solutes that dissolve in the same solvent, often used to analyse inks or food colourings.
蒸馏用于从溶液中分离溶剂，或分离沸点不同的液体。液体沸腾，蒸汽被冷却冷凝回液体，并被收集。色谱法分离溶解在同一种溶剂中的不同溶质，常用于分析墨水或食用色素。
9. Key Laboratory Equipment | 关键实验设备
Knowing the names of apparatus helps you follow instructions and work safely. A beaker is a wide cylindrical container used for mixing, heating, and holding liquids. A conical flask (Erlenmeyer flask) has a narrow neck to reduce splashes during mixing.
熟悉仪器名称有助于你遵循指令并安全操作。烧杯是一种宽口圆柱形容器，用于混合、加热和盛放液体。锥形瓶（三角烧瓶）瓶颈较窄，可减少混合时液体飞溅。
A test tube is a small glass tube used to hold or heat tiny amounts of substances. A Bunsen burner provides a clean, adjustable flame for heating. It is often used with a tripod and gauze to support apparatus above the flame.
试管是一种小型玻璃管，用于盛放或加热微量物质。本生灯提供清洁、可调节的火焰用于加热，通常与三脚架和石棉网配合使用，将仪器支撑在火焰上方。
An evaporating dish is used to evaporate liquids from a solution gently. A measuring cylinder measures liquid volumes accurately. Always read the bottom of the meniscus at eye level for a precise reading.
蒸发皿用于从溶液中温和地蒸发液体。量筒用于准确量取液体体积。读数时视线应与液面的弯月面底部保持水平，以获得准确读数。
10. Common Chemical Formulas and Symbols | 常见化学式与符号
Each element has a one- or two-letter symbol, always starting with a capital letter. The formula of a compound shows the symbols of the elements and the ratio of atoms. For example, H₂O means two hydrogen atoms bonded to one oxygen atom.
每种元素都有一个一字母或两字母的符号，始终以大写字母开头。化合物的化学式标示了元素符号和原子比例。例如，H₂O 表示两个氢原子与一个氧原子键合。
| Substance | Formula | Memory clue |
|---|---|---|
| Water | H₂O | 'Two H's and one O make H₂O flow' |
| Carbon dioxide | CO₂ | 'C and two O's – what plants use to grow' |
| Oxygen gas | O₂ | 'Two atoms together as a diatomic molecule' |
| Hydrogen gas | H₂ | 'Lightest gas, comes in pairs' |
| Sodium chloride | NaCl | 'Na from natrium, Cl from chlorine – table salt' |
| Hydrochloric acid | HCl | 'H + Cl – found in stomach acid' |
| Sulfuric acid | H₂SO₄ | 'Battery acid – handle with care' |
Recognising these common formulas will speed up your equation writing. Note that many non-metal gases exist as diatomic molecules: H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂. Remember the mnemonic 'Have No Fear Of Ice Cold Beer' to recall the seven diatomic elements.
识别这些常见化学式能加快你书写方程式的速度。请注意，许多非金属气体以双原子分子形式存在：H₂、N₂、O₂、F₂、Cl₂、Br₂、I₂。可以用一句口诀 'Have No Fear Of Ice Cold Beer' 来记住这七种双原子元素。
11. Memory Tricks for Terminology | 术语记忆技巧
Use word associations to lock in definitions. For exothermic, think 'ex-it' – heat exits. Endothermic sounds like 'enter' – heat enters. This visual cue helps you never confuse the two.
利用词语联想来牢记定义。对于放热（exothermic），想想 'ex-it'——热量出去（exit）。吸热（endothermic）听起来像 'enter'——热量进入。这个视觉提示能让你永远不会混淆这两个概念。
For the difference between a compound and a mixture, picture a cake (compound) where the ingredients are chemically changed and cannot be separated back into flour and eggs. A salad is a mixture – you can still pick out the tomatoes.
要区分化合物和混合物，可以想象蛋糕（化合物），其原料已经发生了化学变化，无法再变回面粉和鸡蛋。而沙拉是混合物——你依然可以把西红柿挑出来。
Create silly stories for the reactivity or properties of groups. For Group 1 (alkali metals), which react violently with water: 'Lithium is little, sodium shouts, potassium explodes!' This pattern helps you recall that reactivity increases down the group.
为各族元素的反应性或性质编一些夸张的故事。对于遇水剧烈反应的第 1 族（碱金属）：'锂轻轻冒泡，钠高声尖叫，钾轰然爆炸！' 这个模式能帮你记住从上到下反应性增强。
Flashcards are your friends. Write the term on one side and the definition plus a doodle on the other. The doodle creates a mental image, which is much stickier than words alone.
闪卡是好帮手。一面写术语，另一面写定义并加上简笔画。简笔画会形成心理图像，这比单单文字更容易记住。
12. Quick Self-Test Glossary | 快速自测词汇表
Cover the right column and translate the English terms into your own words. Then check the Chinese definition to see if you got all the key points. Revisit any term that feels shaky.
盖住右栏，试着用自己的话说出每个英文术语的含义，然后对照中文定义检查是否抓住了所有要点。对任何感到模糊的术语都要回头复习。
| English Term | 简洁中文定义 |
|---|---|
| Atom | 元素的最小粒子 |
| Element | 仅由一种原子组成的纯净物 |
| Compound | 不同元素化学键合形成的物质 |
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