📚 KS3 Cambridge Chemistry: Vocabulary & Terminology Quick Memorisation Guide | KS3 Cambridge 化学：词汇术语速记指南
Welcome to your quick memorisation guide for KS3 Cambridge Chemistry! Mastering scientific vocabulary is the foundation for understanding key concepts and performing well in assessments. This guide breaks down essential terms into easy-to-remember chunks, using word origins, mnemonics, comparisons and visual associations. Let’s make those tricky words stick.
欢迎来到KS3剑桥化学词汇速记指南！掌握科学词汇是理解核心概念、在考试中取得好成绩的基础。本指南把重要的术语拆解成易于记忆的模块，运用词源、助记、对比和联想，帮助你牢牢记住这些看似复杂的单词。
1. Atoms, Elements and Compounds | 原子、元素和化合物
An atom is the smallest particle of an element that can exist. It comes from the Greek atomos, meaning ‘indivisible’. Think of it as the ultimate single building block — you cannot cut an atom of an element into something simpler and still have that element.
原子是元素能够存在的最小粒子。这个词来源于希腊语 atomos，意为“不可分割”。你可以把它想象成最基本的积木——你无法把一个元素的原子切割成更简单的东西而依然保持该元素。
An element is a pure substance made of only one type of atom. All known elements are listed on the Periodic Table. A compound is a substance formed when two or more different elements are chemically joined together. The atoms are bonded in fixed proportions, and the compound has very different properties from the elements it contains. Water (H₂O) is a compound made from hydrogen and oxygen.
元素是由同一种原子组成的纯物质。所有已知元素都列在元素周期表上。化合物是由两种或更多不同元素通过化学键结合而成的物质。原子以固定的比例结合，化合物的性质与组成它的元素完全不同。水（H₂O）就是由氢和氧组成的化合物。
Memory tip: Element = ‘elementary’ – the simplest form, one type of atom. Compound = ‘com-‘ (together) + ‘pound’ (from Latin ponere, to put) – elements put together. Picture a key and a lock joining to make a new object.
记忆窍门：Element（元素）与 elementary（基础的）相关——最简单的形式，只有一种原子。Compound（化合物）= com-（一起）+ pound（来自拉丁语放置）——元素放在一起。可以想象一把钥匙和一把锁组合成一个新物体。
2. The Periodic Table | 元素周期表
The Periodic Table arranges all elements in order of increasing atomic number. The word ‘periodic’ means repeating patterns occur at regular intervals. When elements are placed in rows (periods) and columns (groups), elements with similar chemical properties fall into the same group. Dmitri Mendeleev famously left gaps for undiscovered elements and predicted their properties.
元素周期表按照原子序数递增的顺序排列所有元素。“周期”一词意味着规律性的模式会定期重复出现。当元素排成行（周期）和列（族）时，化学性质相似的元素会落在同一族中。门捷列夫曾著名地留出空格留给尚未发现的元素，并预测了它们的性质。
Quick reminder: Periods go across →, groups go down ↓. The table is like a library where elements with similar ‘behaviour’ sit on the same shelf (group).
快速提醒：周期横向排列→，族纵向排列↓。周期表就像一个图书馆，行为相似的元素安放在同一个书架（族）上。
3. Groups and Periods | 族与周期
Each group shares the same number of electrons in its outer shell. Group 1 are the alkali metals — very reactive, soft, stored under oil. Group 7 are the halogens — reactive non-metals, including chlorine and iodine. Group 0 (or 8) are the noble gases — unreactive, full outer shells. The period number tells you the number of electron shells an atom has.
同一族的元素最外层电子数相同。第1族是碱金属——非常活泼、质地软、保存在油中。第7族是卤素——活泼的非金属，包括氯和碘。第0族（或第8族）是稀有气体——不活泼，最外层电子已满。周期数告诉我们原子拥有的电子层数量。
Memory aid: Group 1 = one electron in the outer shell, eager to lose it; Group 7 = seven outer electrons, eager to gain one. Noble gases are ‘noble’ because they do not need to react — they already feel complete.
记忆辅助：第1族最外层有1个电子，极想失去；第7族最外层有7个电子，极想获得1个。稀有气体之所以“高贵”，是因为它们不需要反应——它们已经感到完美了。
4. Molecules and Ions | 分子与离子
A molecule is a group of two or more atoms held together by covalent bonds. Molecules can be elements (like O₂, N₂) or compounds (like H₂O, CO₂). An ion is an atom or group of atoms that has gained or lost electrons, giving it a net electric charge. Positive ions are cations, negative ions are anions.
分子是由共价键结合的两个或更多原子的集团。分子可以是单质（如O₂、N₂），也可以是化合物（如H₂O、CO₂）。离子是得到或失去电子而带上净电荷的原子或原子团。带正电的离子叫阳离子，带负电的离子叫阴离子。
Easy recall: molecule = ‘mole’ (mass) + ‘cule’ (small) – a tiny mass. Ion = from Greek ienai ‘to go’; ions go towards electrodes. Cation has a ‘t’ that looks like a plus sign: ca+ion! Anion has an ‘n’ for negative.
轻松牢记：molecule（分子）= mole（质量）+ cule（小）——极小的质量。Ion（离子）源自希腊语“走”；离子走向电极。Cation（阳离子）中有一个像加号的字母 t：ca+ion！Anion（阴离子）中有 n，代表 negative。
5. Mixtures and Pure Substances | 混合物与纯物质
A mixture consists of two or more substances that are not chemically joined together. Each substance keeps its original properties, and you can separate them by physical techniques such as filtration or distillation. Mixtures have variable composition — think of sand and salt mixed together.
混合物由两种或多种没有通过化学键结合的物质组成。每种物质保持原有的性质，你可以用过滤或蒸馏等物理方法将它们分开。混合物的组成不固定——想一想沙子和盐混合在一起的情景。
A pure substance is either a single element or a single compound. It has a fixed, sharp melting point and boiling point. Pure water boils exactly at 100°C (at sea level) and melts at 0°C, while a mixture melts over a range of temperatures.
纯物质要么是单一元素，要么是单一化合物。它有固定、明确的熔点和沸点。纯水在海平面恰好100°C沸腾、0°C融化，而混合物会在一段温度范围内熔化。
Memory phrase: Mixture = mixed – you can unmix it physically. Pure = single thing – no extras.
记忆口诀：混合物 = 混在一起的——你能用物理方法把它们分开。纯物质 = 单一的东西——没有额外成分。
6. Physical and Chemical Changes | 物理变化与化学变化
A physical change is one where no new substance is made. The material changes its state or shape but its chemical identity stays the same. Examples include melting ice, boiling water, dissolving sugar in water, and bending a metal rod. Physical changes are usually reversible.
物理变化是指没有新物质生成的变化。材料的状态或形状改变，但其化学身份不变。例子包括冰融化成水、水沸腾、糖溶于水、弯曲金属棒。物理变化通常是可逆的。
A chemical change (chemical reaction) produces one or more new substances. Signs of a chemical change include a colour change, a gas being given off (effervescence), formation of a precipitate, an energy change (heat, light) and an irreversible process. Burning wood and rusting iron are chemical changes.
化学变化（化学反应）会产生一种或多种新物质。化学变化的迹象包括颜色改变、有气体放出（气泡）、生成沉淀、能量变化（热、光）以及过程不可逆。木材燃烧和铁生锈都是化学变化。
Remember: Physical = no new substance, Chemical = new substance. Think of physical as rearranging furniture in a room — the room is still the same room. Chemical is like knocking down a wall — you’ve made something different.
牢记：物理变化 = 无新物质，化学变化 = 有新物质。物理变化好比在房间里重新布置家具——房间还是同一个房间。化学变化就像拆掉一面墙——你创造了不同的空间。
7. Reactions: Reactants and Products | 反应物与生成物
In a chemical reaction, the starting substances are called reactants. The substances formed at the end are products. We represent reactions using word equations and symbol equations. The arrow (→) means ‘produces’ or ‘yields’.
在化学反应中，起始物质叫反应物，最终生成的物质叫生成物。我们使用文字方程式和符号方程式来表示反应。箭头（→）表示“生成”或“产生”。
The law of conservation of mass states that no atoms are created or destroyed in a chemical reaction. The total mass of reactants equals the total mass of products. This is why we must balance symbol equations, making the number of each type of atom equal on both sides.
质量守恒定律指出，化学反应中原子既不凭空产生也不凭空消失。反应物的总质量等于生成物的总质量。因此我们必须配平符号方程式，使得两边每种原子的数目相等。
Visual trick: The arrow is like a bridge from ‘before’ to ‘after’. Reactants react, products have been produced.
视觉技巧：箭头就像一座从“之前”到“之后”的桥。反应物进行反应，生成物被生产出来。
8. Acids, Bases and Alkalis | 酸、碱与碱溶液
An acid is a substance with a pH less than 7. Acids release hydrogen ions (H⁺) when dissolved in water. Common laboratory acids include hydrochloric acid (HCl), sulfuric acid (H₂SO₄) and nitric acid (HNO₃). Acids taste sour and turn blue litmus paper red.
酸是pH小于7的物质。酸溶于水时会释放出氢离子（H⁺）。实验室常见的酸包括盐酸（HCl）、硫酸（H₂SO₄）和硝酸（HNO₃）。酸有酸味，能把蓝色石蕊试纸变红。
A base is any substance that neutralises an acid to form a salt and water. An alkali is a soluble base that releases hydroxide ions (OH⁻) in water. Alkalis feel soapy and turn red litmus paper blue. Common alkalis include sodium hydroxide (NaOH) and potassium hydroxide (KOH).
碱（base）是能够中和酸生成盐和水的任何物质。碱溶液（alkali）是可溶性碱，溶于水释放氢氧根离子（OH⁻）。碱溶液手感滑腻如肥皂，能使红色石蕊试纸变蓝。常见的碱溶液有氢氧化钠（NaOH）和氢氧化钾（KOH）。
Mnemonics: Acid starts with ‘A’ and attacks (reactive). Alkali contains ‘kali’ — think of ‘kalium’, the old name for potassium, often found in bases. Litmus test: Blue to Red = Acid (BRA). Red to Blue = Alkali (RBA).
助记符：Acid（酸）以 A 开头，具有攻击性。Alkali（碱溶液）中含有“kali”——想到钾的旧名 kalium，常出现在碱中。石蕊测试：蓝变红是酸（英文首字母BRA），红变蓝是碱（RBA）。
9. pH Scale and Neutralisation | pH 值与中和反应
The pH scale measures how acidic or alkaline a solution is. It ranges from 0 (strong acid) to 14 (strong alkali), with 7 being neutral. Universal indicator turns a range of colours: red in strong acids, green in neutral, purple in strong alkalis.
pH 标度衡量溶液的酸碱程度，范围从0（强酸）到14（强碱），7为中性。通用指示剂会显示一系列颜色：强酸中为红色，中性时呈绿色，强碱中呈紫色。
Neutralisation is the reaction between an acid and an alkali (or base) that produces a salt and water. The general equation is:
中和反应是酸与碱溶液（或碱）之间的反应，生成盐和水。通式为：
Acid + Alkali → Salt + Water
For example, hydrochloric acid reacts with sodium hydroxide to form sodium chloride (common salt) and water:
例如，盐酸与氢氧化钠反应生成氯化钠（食盐）和水：
HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
Memory link: Neutralisation brings the pH towards neutral. Think of it as balancing an acid ‘negative’ and an alkali ‘positive’ to become ‘neutral’.
记忆联系：中和反应将pH值趋近于中性。就像平衡酸的“负极”和碱的“正极”，最终达到“中性”。
10. State Symbols and Equations | 状态符号与化学方程式
State symbols indicate the physical state of each substance in a reaction. They are written in parentheses after the chemical formula:
- (s) = solid
- (l) = liquid
- (g) = gas
- (aq) = aqueous (dissolved in water, from Latin aqua)
The symbol (aq) is only used when water is the solvent.
状态符号表明反应中各物质的物理状态，写在化学式后的括号内：
- (s) = 固体
- (l) = 液体
- (g) = 气体
- (aq) = 水溶液（溶于水，来自拉丁语 aqua）
只有当溶剂是水时才使用 (aq)。
A balanced symbol equation has the same number of each type of atom on both sides. For instance, the combustion of methane:
配平的符号方程式两边每种原子的数目相等。例如，甲烷的燃烧：
CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l)
Memorising state symbols: Solid = shape, Liquid = flow, Gas = invisible, Aqueous = aquatic. Think of (aq) as ‘aquarium’.
记住状态符号：固体有形，液体流动，气体看不见，水溶液（aq）联想到 aquarium（水族馆）。
11. Separation Techniques | 分离技术
Separation techniques are used to separate mixtures without changing the chemical nature of the components. Choosing the right method depends on the physical properties of the substances involved.
分离技术用于将混合物分开，而不改变成分的化学性质。选择正确的方法取决于所涉物质的物理性质。
Filtration separates an insoluble solid from a liquid. The mixture is poured through filter paper; the solid (residue) stays and the liquid (filtrate) passes through. Evaporation and crystallisation separate a soluble solid from a solution. Evaporating the solvent leaves solid crystals behind. Crystallisation is more gentle and produces larger, purer crystals.
过滤用于分离不溶性固体和液体。混合物倒入滤纸，固体（残渣）留在纸上，液体（滤液）通过。蒸发与结晶用于从溶液中分离可溶性固体。蒸发溶剂得到固体晶体。结晶法更温和，可产生更大、更纯的晶体。
Simple distillation separates a solvent from a solution, or liquids with very different boiling points. The mixture is heated, the more volatile component vaporises first, is cooled and condensed back into liquid, and collected as distillate. Chromatography separates mixtures of soluble substances, like coloured inks. A mobile phase carries the mixture over a stationary phase; substances travel at different speeds, producing a chromatogram.
简单蒸馏用于分离溶剂与溶液，或沸点相差很大的液体。加热混合物，较易挥发的组分先汽化，经冷却冷凝回到液态，收集为馏出液。色谱法用于分离可溶性物质的混合物，如彩色墨水。流动相带着混合物经过固定相；各物质移动速度不同，形成色谱图。
Quick check: Filtration – size matters (large particles trapped). Dist
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