📚 Year 7 CCEA Chemistry: Bridging Guide for Academic Progression | Year 7 CCEA化学：升学衔接指南
As you finish Year 7, you have built a strong foundation in CCEA Chemistry. This bridging guide revisits key concepts from the particle model to acids, and shows how they will support your learning in Year 8. Use it to consolidate your knowledge and prepare confidently for the next stage.
完成Year 7的学习，你已经为CCEA化学打下了坚实的基础。本衔接指南回顾从粒子模型到酸和碱的重要概念，并展示它们如何帮助你迎接Year 8的化学学习。用它来巩固知识，自信地迈向新阶段。
1. The Particle Model | 粒子模型
Everything around you is made of tiny particles that are far too small to see. These particles are always moving.
你周围的一切都由极微小的粒子组成，这些粒子一直在运动。
The energy of the particles determines whether a substance is a solid, liquid or gas.
粒子的能量决定了物质是固体、液体还是气体。
In solids, particles are packed closely together and can only vibrate in place.
在固体中，粒子紧密排列，只能在原地振动。
In gases, particles have lots of energy, move randomly and spread far apart.
气体中粒子能量很高，无规则运动且彼此远离。
2. States of Matter | 物质的状态
Solids have a fixed shape and volume because particles are held tightly in a regular arrangement.
固体有固定的形状和体积，因为粒子被紧紧地固定在规则的排列中。
Liquids take the shape of their container but keep a fixed volume; particles can slide past each other.
液体与容器形状一致但体积不变；粒子可以相互滑动。
Gases fill the entire volume of a container; their particles move freely and exert pressure when they hit the walls.
气体充满整个容器；粒子自由运动，撞击容器壁时产生压力。
Changes of state, such as melting, boiling, freezing and condensation, are reversible physical changes.
状态变化（熔化、沸腾、凝固和冷凝）是可逆的物理变化。
3. Atoms, Elements and the Periodic Table | 原子、元素与周期表
An atom is the smallest particle of an element that can exist. All substances are made of atoms.
原子是元素能够存在的最小粒子。所有物质都由原子构成。
An element is a pure substance made of only one type of atom. There are about 100 elements shown on the periodic table.
元素是只由一种原子组成的纯净物。周期表中列出了大约100种元素。
Each element has a unique chemical symbol, for example, O for oxygen, Fe for iron and Na for sodium.
每种元素都有独特的化学符号，例如氧是O，铁是Fe，钠是 Na。
In Year 8, you will learn more about how elements are arranged in groups and periods, and what the atomic number means.
在Year 8，你会学习元素如何按族和周期排列，以及原子序数的含义。
4. Compounds and Mixtures | 化合物与混合物
A compound forms when two or more different elements chemically join together. The properties of a compound are different from the elements it contains.
当两种或多种不同元素化学结合在一起时就形成化合物。化合物的性质与组成它的元素不同。
A mixture contains two or more substances that are not chemically bonded. Each substance keeps its own properties.
混合物包含两种或多种未发生化学结合的物质。每种物质保持自身性质。
Here is a quick comparison:
快速对比如下：
| Feature | Compound | Mixture |
|---|---|---|
| Composition | Elements chemically bonded in fixed ratio | Substances mixed but not bonded |
| Separation | Only by chemical reactions | By physical techniques (filtration, etc.) |
| Properties | Different from elements | Similar to individual substances |
Common examples: water (H₂O) is a compound, while salty water is a mixture.
常见例子：水(H₂O)是化合物，而盐水是混合物。
5. Separating Techniques | 分离技术
Filtration separates an insoluble solid from a liquid. The solid stays on the filter paper as the liquid passes through.
过滤用于分离不溶性固体和液体。固体留在滤纸上，液体通过。
Evaporation removes the solvent to leave behind a dissolved solid, for example, obtaining salt from salt solution.
蒸发除去溶剂，留下溶解的固体，例如从盐溶液中得到盐。
Simple distillation separates a solvent from a solution by boiling and condensing the vapor. This gives pure water from salt water.
简单蒸馏通过沸腾和冷凝蒸汽从溶液中分离溶剂，可以从盐水中得到纯水。
Chromatography separates mixtures of coloured substances, such as inks or food dyes, based on how they move on paper.
色谱法根据有色物质在纸上移动的距离分离混合物，比如墨水或食用色素。
6. Acids and Alkalis | 酸和碱
Acids are substances with a sour taste (in dilute food forms) and turn blue litmus paper red. Common lab acids include hydrochloric acid and sulfuric acid.
酸有酸味（在食品稀释形式中），能使蓝色石蕊试纸变红。实验室常见的酸有盐酸和硫酸。
Alkalis are soluble bases that feel soapy and turn red litmus paper blue. Sodium hydroxide is a typical alkali.
碱是可溶的、有滑腻感并能将红色石蕊试纸变蓝的物质。氢氧化钠是典型的碱。
The pH scale measures how acidic or alkaline a solution is. It runs from 0 (very acidic) to 14 (very alkaline), with 7 being neutral.
pH标度衡量溶液的酸碱性。范围从0（强酸性）到14（强碱性），7为中性。
Universal indicator gives a range of colours across the pH scale, helping us compare strengths of acids and alkalis.
通用指示剂在pH标度上呈现一系列颜色，帮助我们比较酸和碱的强弱。
7. Neutralisation | 中和反应
Neutralisation happens when an acid reacts with an alkali to produce a salt and water.
当酸与碱反应生成盐和水时，就发生了中和反应。
The general word equation is: acid + alkali → salt + water
通用文字方程式是：酸 + 碱 → 盐 + 水
For example: hydrochloric acid + sodium hydroxide → sodium chloride + water
例如：盐酸 + 氢氧化钠 → 氯化钠 + 水
Neutralisation has everyday uses, such as treating acidic soil with lime (an alkali) or relieving indigestion with antacid tablets.
中和在日常生活中有很多应用，比如用石灰（碱）改良酸性土壤，或用抗酸药片缓解消化不良。
8. Signs of a Chemical Reaction | 化学反应的迹象
You have learned that a chemical reaction makes new substances. Look for these signs to know if a reaction has taken place:
你已经知道化学反应会生成新物质。通过以下迹象可以判断是否发生了化学反应：
– Colour change: a new colour appears that was not there before.
– 颜色变化：出现原本没有的颜色。
– Gas production: bubbles or fizzing, often without heating.
– 产生气体：出现气泡或嘶嘶声，通常无需加热。
– Precipitate: a solid forms when two clear solutions are mixed
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