📚 Year 8 SQA Chemistry: Key Terms Quick Memorisation Guide | 八年级 SQA 化学：关键术语速记指南
Mastering the vocabulary of chemistry is the first step to truly understanding the subject. In Year 8 SQA Science, chemistry introduces a range of new words that describe matter, changes, and laboratory techniques. This guide will help you memorise key terms quickly through clear definitions, examples, and simple memory hooks. From 'atom' to 'pH', you will build a solid foundation for all future chemistry learning.
掌握化学词汇是真正理解这门学科的第一步。在八年级 SQA 科学课程中，化学会引入一系列描述物质、变化和实验技术的新词汇。本指南将通过清晰的定义、实例和简单的记忆线索，帮助你快速记住关键术语。从'原子'到'pH'，你将为今后的化学学习打下坚实基础。
1. States of Matter | 物质状态
There are three common states of matter: solid, liquid and gas. Solids have a fixed shape and volume because particles are tightly packed in a regular pattern. Liquids have a fixed volume but take the shape of the container; their particles are close together but can move past each other. Gases have no fixed shape or volume; particles are far apart and move rapidly in all directions. The changes between these states – melting, freezing, boiling, condensation and sublimation – are physical changes.
物质有三种常见状态：固态、液态和气态。固体有固定的形状和体积，因为粒子紧密排列成规则的结构。液体有固定的体积，但会随容器改变形状；其粒子虽然紧挨着，但可以相互滑动。气体没有固定的形状或体积；粒子相距很远，并朝各个方向快速运动。这些状态之间的变化——熔化、凝固、沸腾、冷凝和升华——都属于物理变化。
| State | Particle arrangement | Shape/Volume | Memory hook |
|---|---|---|---|
| Solid | Tightly packed, regular | Fixed shape & volume | Soldiers standing to attention |
| Liquid | Close, can slide | Fixed volume, no fixed shape | Dancers on a crowded floor |
| Gas | Far apart, random | No fixed shape or volume | Children in a playground |
状态/粒子排列/形状与体积/记忆钩子（中文对应）：固体—紧密规则排列—固定形状与体积—像立正的士兵；液体—紧挨可滑动—固定体积无定形—像舞池中的人群；气体—相距很远随意运动—无定形无定体积—像操场上的孩子。
2. Physical vs Chemical Changes | 物理变化与化学变化
A physical change alters the state or appearance of a substance but does not create a new substance. Examples include melting ice, boiling water, dissolving sugar or cutting paper. These changes are often easy to reverse. A chemical change (chemical reaction) produces one or more new substances and is usually difficult to reverse. Signs of a chemical change include colour change, temperature change, gas bubbles, and formation of a precipitate (an insoluble solid). Burning wood, rusting iron and baking a cake are chemical changes.
物理变化会改变物质的状态或外观，但不会产生新物质。例如冰融化、水沸腾、糖溶解或剪纸。这些变化通常容易逆转。化学变化（化学反应）会产生一种或多种新物质，并且通常难以逆转。化学变化的迹象包括颜色改变、温度变化、产生气泡以及生成沉淀（不溶性固体）。木头燃烧、铁生锈和烤蛋糕都属于化学变化。
Memory tip: 'Physical is like moving furniture – same stuff, different look. Chemical is like baking – you cannot get the flour back.'
记忆窍门：'物理变化就像挪家具——东西还是那些，样子变了。化学变化则像烘焙——你没法把面粉变回来。'
3. Atoms, Elements, Molecules & Compounds | 原子、元素、分子与化合物
An atom is the smallest particle of an element that can take part in a chemical reaction. An element is a pure substance made of only one type of atom – all the atoms have the same number of protons. Examples: oxygen (O), iron (Fe), gold (Au). A molecule is two or more atoms chemically bonded together; they can be the same element (O₂) or different elements (H₂O). A compound is a substance made from two or more different elements chemically bonded in fixed proportions. All compounds are molecules, but not all molecules are compounds (e.g. O₂ is a molecule but not a compound).
原子是元素中能参与化学反应的最小微粒。元素是由同一种原子组成的纯净物——所有原子具有相同的质子数。例如：氧 (O)、铁 (Fe)、金 (Au)。分子是两个或更多原子通过化学键结合在一起的粒子；这些原子可以是同种元素（如 O₂），也可以是不同元素（如 H₂O）。化合物是由两种或以上不同元素以固定比例通过化学键结合而成的物质。所有化合物都是分子，但并非所有分子都是化合物（例如 O₂ 是分子而非化合物）。
Memory trick: ' two or more different atoms chemically joined. A molecule is just a group of atoms stuck together, like a team.'
记忆窍门：'元素 = 一种原子；化合物 = 两种或以上不同的原子化学结合在一起。分子就是一组粘在一起的原子，像一个团队。'
4. The Periodic Table: Groups and Periods | 元素周期表：族与周期
The periodic table organises all known elements. 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. Horizontal rows are called periods. Metals are on the left and centre, non-metals on the right. Important groups for Year 8: Group 1 – alkali metals (very reactive, e.g. sodium Na), Group 7 – halogens (reactive non-metals, e.g. chlorine Cl), Group 0 (or 8) – noble gases (unreactive, e.g. helium He).
元素周期表将所有已知元素组织起来。竖列称为族；同一族的元素具有相似的化学性质，因为它们最外层电子数相同。横行称为周期。金属位于左侧和中间，非金属在右侧。八年级需掌握的重要族：第1族——碱金属（非常活泼，如钠 Na），第7族——卤素（活泼非金属，如氯 Cl），第0族（或第8族）——稀有气体（不活泼，如氦 He）。
Quick recall: 'Group 1 – one electron in outer shell, very keen to react. Group 7 – seven electrons, one short of a full shell. Group 0 – full outer shell, happy and stable.'
快速记忆：'第1族——最外层一个电子，非常想反应。第7族——最外层七个电子，差一个就满了。第0族——最外层已满，稳定又满足。'
5. Mixtures and Pure Substances | 混合物与纯净物
A pure substance contains only one type of element or compound. It has a fixed melting and boiling point. A mixture contains two or more different substances that are not chemically bonded. Each part of a mixture keeps its own properties. Air is a mixture of gases (nitrogen, oxygen, carbon dioxide); seawater is a mixture of water and dissolved salts. Mixtures can be separated by physical methods such as filtration, distillation and chromatography.
纯净物只含有一种元素或化合物，具有固定的熔点和沸点。混合物则包含两种或以上未发生化学结合的不同物质，其中各组分仍保留自身的性质。空气是气体混合物（氮气、氧气、二氧化碳）；海水是水和溶解盐类的混合物。混合物可通过过滤、蒸馏、色谱等物理方法分离。
Memory: 'A pure substance is like a football team wearing identical kits. A mixture is like fans of different teams sitting together – they are just mixed, not joined.'
记忆：'纯净物像穿着相同球衣的足球队。混合物则像不同球队的球迷坐在一起——只是混在一块，并没有结合。'
6. Separation Techniques | 分离技术
Different mixtures require different methods to be separated. Filtration separates an insoluble solid from a liquid (e.g. sand from water). Evaporation removes a liquid to leave a dissolved solid behind (e.g. salt from salt water). Distillation separates a liquid from a solution based on boiling points; the liquid evaporates and is then condensed back. Chromatography separates dissolved substances that move at different speeds through paper (e.g. separating ink colours).
不同的混合物需要不同的方法进行分离。过滤用于将不溶性固体从液体中分离出来（例如沙和水的分离）。蒸发通过去除液体留下溶解的固体（例如从盐水中获得盐）。蒸馏根据沸点的不同将液体从溶液中分离；液体先蒸发再冷凝回收。色谱法根据溶解物质在纸上移动速度的不同来进行分离（例如分离墨水颜色）。
| Technique | What it separates | Key equipment |
|---|---|---|
| Filtration | Insoluble solid + liquid | Filter funnel, filter paper |
| Evaporation | Soluble solid + liquid | Evaporating dish, heat source |
| Distillation | Liquid + dissolved solid / two liquids with different boiling points | Liebig condenser, flask, thermometer |
| Chromatography | Dissolved colours / substances | Chromatography paper, solvent |
技术/分离对象/关键仪器（中文）：过滤—不溶性固体与液体—漏斗、滤纸；蒸发—可溶性固体与液体—蒸发皿、热源；蒸馏—液体与溶解固体/沸点不同的两种液体—冷凝管、烧瓶、温度计；色谱法—溶解的颜色/物质—色谱纸、溶剂。
7. Acids, Alkalis and the pH Scale | 酸、碱与 pH 标度
An acid is a substance that releases hydrogen ions (H⁺) in water. They taste sour (but never taste in the lab!) and turn blue litmus paper red. Examples: hydrochloric acid (HCl), sulfuric acid (H₂SO₄), citric acid in lemons. An alkali is a soluble base that releases hydroxide ions (OH⁻) in water. Alkalis feel soapy and turn red litmus paper blue. Examples: sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)₂). The pH scale (0– ral, pH > 7 alkaline. Universal indicator shows a rainbow of colours from red (strong acid) to purple (strong alkali).
酸是在水中释放氢离子（H⁺）的物质。它们尝起来酸酸的（但切勿在实验室品尝！），并能使蓝色石蕊试纸变红。例如：盐酸 (HCl)、硫酸 (H₂SO₄)、柠檬中的柠檬酸。碱是可溶性碱，在水中释放氢氧根离子（OH⁻）。碱有滑腻感，能使红色石蕊试纸变蓝。例如：氢氧化钠 (NaOH)、氢氧化钙 (Ca(OH)₂)。pH 标度（0–14）用于衡量溶液的酸碱度：pH < 7 为酸性，pH = 7 为中性，pH > 7 为碱性。通用指示剂会呈现从红（强酸）到紫（强碱）的彩虹色。
Memory phrase: 'Acid – H⁺ present; Alkali – OH⁻ present. Low pH = acid, high pH = alkali, seven is neutral just like heaven.'
记忆口诀：'酸含 H⁺，碱含 OH⁻。pH 低为酸，高为碱，七是中性像晴天。'
8. Chemical Reactions and Word Equations | 化学反应与文字方程式
A chemical reaction happens when substances (reactants) change into new substances (products). We can model this with a word equation: Reactant + Reactant → Product. The arrow means 'reacts to form' ydroxide + hydrochloric acid → sodium chloride + water. Word equations describe the substances involved without needing formulae. Always check that the reaction makes sense by listing the names correctly.
当物质（反应物）转变成新物质（生成物）时，就发生了化学反应。我们可以用文字方程式来表示：反应物 + 反应物 → 生成物。箭头表示“反应生成”。例如：镁 + 氧气 → 氧化镁。另一个常见的反应是酸 + 碱 → 盐 + 水；这叫作中和反应。氢氧化钠 + 盐酸 → 氯化钠 + 水。文字方程式不需要化学式，直接描述参与反应的物质。书写时一定要确保名称正确，反应合理。
Tip: Think of a word equation like a recipe – you list the ingredients (reactants) and what you cook (products).
小贴士：把文字方程式想象成一份食谱——列出食材（反应物）和做好的菜肴（生成物）。
9. Solutions, Solvents and Solubility | 溶液、溶剂与溶解度
A solution is a mixture where a solute dissolves in a solvent. The solute is the substance that dissolves (e.g. salt), and the solvent is the liquid that does the dissolving (e.g. water). A saturated solution contains the maximum amount of solute that can dissolve at that temperature. Solubility (often in g per 100g water) tells us how much solute will dissolve. Solubility usually increases with temperature for solids in water, but for gases it decreases as temperature rises.
溶液是溶质溶解在溶剂中形成的混合物。溶质是被溶解的物质（如盐），溶剂是进行溶解的液体（如水）。饱和溶液含有该温度下所能溶解的最大溶质量。溶解度（通常以克/100克水表示）告诉我们能溶解多少溶质。对于固体在水中的溶解，溶解度通常随温度升高而增大；但对于气体，温度越高溶解度越低。
Memory aid: ' vent = Solution. Solvent is the large excess, like water in a cup of tea dissolving sugar.'
记忆辅助：'溶质 + 溶剂 = 溶液。溶剂是大量存在的那个，好比茶水里溶解糖的液体。'
10. Rates of Reaction | 反应速率
The rate of reaction tells us how fast reactants are used up or products are made. Four main factors affect the rate: temperature (higher temp → faster particles → more collisions), concentration (more particles in the same volume → more collisions), surface area (smaller pieces → more area exposed → faster reaction), and catalysts (substances that speed up reactions without being used up). A common example: marble chips (calcium carbonate) react faster with acid when powdered because of greater surface area.
反应速率表示反应物消耗或产物生成的快慢。影响速率的四个主要因素是：温度（温度越高 → 粒子运动越快 → 碰撞更多）、浓度（相同体积内粒子越多 → 碰撞越多）、表面积（颗粒越小 → 暴露面积越大 → 反应越快）和催化剂（能加快反应而自身不被消耗的物质）。一个常见例子是：大理石碎片（碳酸钙）与酸反应，粉末状比块状快得多，因为表面积更大。
Remember: 'Faster reactions need more successful collisions – increase temp, conc or surface area, or add a catalyst.'
记住：'加快反应需要更多的有效碰撞——提高温度、浓度或表面积，或者加入催化剂。'
11. Key Metals and Non-metals | 主要金属与非金属
Elements are broadly divided into metals and non-metals. Metals are typically shiny, good conductors of heat and electricity, malleable (can be hammered into sheets) and ductile (can be drawn into wires). Examples: iron (Fe), copper (Cu), aluminium (Al), gold (Au). Non-metals are generally dull, brittle, do not conduct electricity (except graphite, a form of carbon). Examples: oxygen (O), sulfur (S), chlorine (Cl), carbon (C). A few elements like silicon are called semi-metals (metalloids).
元素大致分为金属和非金属。金属通常有光泽，是热和电的良导体，具有延展性（可锤打成薄片）和韧性（可拉成丝）。例如：铁 (Fe)、铜 (Cu)、铝 (Al)、金 (Au)。非金属则一般暗淡、脆性，不导电（石墨除外，它是碳的一种形态）。例如：氧 (O)、硫 (S)、氯 (Cl)、碳 (C)。少数元素如硅被称为半金属（类金属）。
Memory: 'Metals are strong, shiny and kind to electricity; non-metals are opposite – dull and unfriendly to current.'
记忆：'金属强壮、闪亮、导电友好；非金属相反——暗淡、对电流不友好。'
12. Common Laboratory Apparatus | 常见实验仪器
Being able to name and use basic equipment is essential. Below is a quick-reference table of apparatus you will encounter in Year 8 chemistry.
能够正确说出并使用基本仪器是一项重要技能。以下是你将在八年级化学中遇到的仪器快速参考表。
| Apparatus (English) | 仪器（中文） | Main use |
|---|---|---|
| Beaker | 烧杯 | Holding, mixing or heating liquids |
| Conical flask | 锥形瓶 | Mixing by swirling, titrations |
| Measuring cylinder | 量筒 | Measuring approximate volumes of liquids |
| Test tube | 试管 | Holding small samples for heating
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