📚 Formula & Theorem Quick Reference Handbook | 公式定理速查手册
This handbook gathers the essential scientific rules, principles and 'formulae' you will meet in Year 7 AQA Chemistry. Understanding these key ideas - from the particle model to acid reaction patterns - helps you explain observations, predict outcomes and write equations correctly. Keep it handy for quick revision.
本手册汇集了你在 Year 7 AQA 化学中会遇到的科学规则、原理与“公式”。理解粒子模型、质量守恒、酸反应规律等核心概念，能帮助你解释现象、预测结果并正确书写化学方程式。请随时翻阅，速查速记。
1. States of Matter and Particle Model | 物质状态与粒子模型
All substances are made of tiny particles. The way these particles are arranged and move determines whether a material is a solid, a liquid or a gas.
所有物质都由微小粒子构成。粒子的排列方式和运动状态决定了该物质是固体、液体还是气体。
In solids, particles are closely packed in a regular pattern and can only vibrate in fixed positions. This gives solids a fixed shape and volume.
在固体中，粒子紧密排列成规则的结构，只能在固定位置振动，因此固体有固定的形状和体积。
In liquids, particles are still close together but are not in a fixed arrangement; they can slide past each other. Liquids have a fixed volume but take the shape of their container.
在液体中，粒子依然相互靠近但排列不固定，它们可以相互滑动。液体有固定的体积，但形状随容器而变。
In gases, particles are far apart and move rapidly in all directions. Gases have no fixed shape or volume and can be compressed easily.
在气体中，粒子相距很远并快速向各个方向运动。气体没有固定的形状和体积，容易被压缩。
Changing state involves adding or removing energy. Melting, boiling, condensing and freezing are physical reversals - no new substance is made.
状态变化涉及能量的吸收或释放。熔化、沸腾、凝结和凝固都是物理过程，可以逆转，没有新物质生成。
2. Physical and Chemical Changes | 物理变化与化学变化
A physical change alters the appearance or state of a material but does not create new chemical substances. Examples include dissolving sugar in water or melting ice.
物理变化改变物质的外形或状态，但不产生新的化学物质。例如糖溶于水或冰融化。
A chemical change (chemical reaction) always produces at least one new substance with different properties. Signs include colour change, fizzing, temperature change or formation of a precipitate.
化学变化（化学反应）总是生成至少一种性质不同的新物质。常见迹象有颜色改变、冒泡、温度变化或生成沉淀。
Chemical changes are usually difficult to reverse. Word equations and symbol equations are used to represent what happens to the atoms during a reaction.
化学变化通常难以逆转。我们用文字方程式和符号方程式来表示反应中原子的重新组合。
3. Elements, Compounds and Mixtures | 元素、化合物与混合物
An element is a pure substance made of only one type of atom. All known elements are listed on the Periodic Table.
元素是仅由一种原子组成的纯净物。所有已知元素都列在元素周期表中。
A compound contains two or more different elements chemically combined in fixed proportions. Compounds have properties that are different from the elements they are made from.
化合物含有两种或多种不同元素，以固定的比例化学结合。化合物的性质与构成它的元素性质不同。
A mixture consists of two or more substances (elements or compounds) that are not chemically joined. The components keep their own properties and can be separated by physical techniques.
混合物由两种或多种物质（元素或化合物）组成，它们之间没有化学结合。各组分保持自身性质，可以用物理方法分离。
A key theorem: every pure compound has a definite composition by mass - the same elements always combine in the same mass ratio. This is the law of constant composition.
一个重要的定律：每一种纯净化合物都有确定的组成，即相同的元素总是以相同的质量比结合。这就是定组成定律。
4. Chemical Symbols, Formulae and Naming | 化学符号、化学式与命名
Every element has a unique chemical symbol, e.g. H for hydrogen, O for oxygen, Fe for iron. The first letter is always a capital letter; if there is a second letter, it is lowercase.
每种元素都有一个独特的化学符号，如 H 代表氢，O 代表氧，Fe 代表铁。首字母必须大写，若有第二个字母则小写。
The formula of a compound shows which elements are present and the ratio of atoms. Subscript numbers indicate how many atoms of each element: H₂O means 2 hydrogen atoms and 1 oxygen atom.
化合物的化学式表示所含元素及其原子个数比。下标数字表示每种原子的数目：H₂O 表示 2 个氢原子和 1 个氧原子。
a metal combines with a non-metal, the metal name is kept and the non-metal ending becomes '-ide'. For example, sodium + chlorine → sodium chloride.
简单化合物的命名：金属与非金属化合时，保留金属名称，非金属词尾改为“-ide”。例如钠和氯生成氯化钠。
To write a formula from ions, we use the 'cross-over' method. Charges are swapped and simplified if needed.
由离子符号书写化学式时，我们使用“交叉法”，将离子所带电荷数交叉作为对方下标，并化简。
For Aᵐ⁺ and Bⁿ⁻ , formula = AₙBₘ (simplify to smallest whole number ratio)
对于 Aᵐ⁺ 和 Bⁿ⁻，化学式为 AₙBₘ（化简为最简整数比）
| Ion / 离子 | Charge / 电荷 |
|---|---|
| Na⁺ | 1+ |
| Mg²⁺ | 2+ |
| Al³⁺ | 3+ |
| Cl⁻ | 1− |
| O²⁻ | 2− |
5. Law of Conservation of Mass | 质量守恒定律
In a chemical reaction, atoms are rearranged but not created or destroyed. Therefore, the total mass of the reactants always equals the total mass of the products.
在化学反应中，原子只是重新排列，既不会被创造也不会被消灭。因此，反应物的总质量总是等于生成物的总质量。
Total mass of reactants = Total mass of products
反应物的总质量 = 生成物的总质量
If a reaction seems to lose mass, it is usually because a gas has escaped into the air. If mass increases, it is often because a gas from the air has combined with the reactants. All experiments that appear to break the law can be explained by careful measurement of gases.
如果反应看上去质量减少，通常是因为生成的气体逸散到了空气中。如果质量增加，往往是空气中的某种气体参与了反应。所有看似违背质量守恒的实验，都可以通过对气体的精确测量来解释。
6. Writing Word Equations and Simple Formulae | 书写文字方程式与简单化学式
rd equation summarises a reaction in words: reactant + reactant → product. The arrow means 'makes' or 'produces'.
文字方程式用词语概括一个反应：反应物 + 反应物 → 生成物。箭头表示“生成”。
State symbols are often added to show the physical state: (s) solid, (l) liquid, (g) gas, (aq) aqueous (dissolved in water).
常常加入状态符号以表示物质的物理状态：(s) 固体, (l) 液体, (g) 气体, (aq) 水溶液。
2MgO(s). Balancing ensures the number of atoms of each element is the same on both sides.
示例：镁 + 氧气 → 氧化镁。符号方程式：2Mg(s) + O₂(g) → 2MgO(s)。配平保证每种元素的原子数目在等式两边相等。
oxygen → carbon dioxide + water. This word equation is very useful when studying burning.
一个常见的燃烧规律：燃料 + 氧气 → 二氧化碳 + 水。在学习燃烧时，这个文字方程式非常有用。
7. Acids, Alkalis and the pH Scale | 酸、碱与 pH 值
Acids are substances that release hydrogen ions (H⁺) in water. Common laboratory acids include hydrochloric acid (HCl), sulfuric acid (H₂SO₄) and nitric acid (HNO₃).
酸是在水中释放氢离子（H⁺）的物质。实验室常见的酸有盐酸（HCl）、硫酸（H₂SO₄）和硝酸（HNO₃）。
Alkalis are soluble bases that release hydroxide ions (OH⁻) in water. Sodium hydroxide (NaOH) is a typical alkali.
碱是可溶的、在水中释放氢氧根离子（OH⁻）的物质。氢氧化钠（NaOH）是一种常见的碱。
The pH scale runs from 0 to 14. Values below 7 are acidic, 7 is neutral, and above 7 are alkaline. Universal indicator turns different colours across the range.
pH 值范围从 0 到 14。小于 7 为酸性，等于 7 为中性，大于 7 为碱性。通用指示剂在不同 pH 值下会显示不同颜色。
| Indicator / 指示剂 | Acid colour / 酸性颜色 | Neutral / 中性 | Alkali colour / 碱性颜色 |
|---|---|---|---|
| Litmus / 石蕊 | Red / 红 | Purple / 紫 | Blue / 蓝 |
| Phenolphthalein / 酚酞 | Colourless / 无色 | Colourless / 无色 | Pink / 粉红 |
| Methyl orange / 甲基橙 | Red / 红 | Orange / 橙 | Yellow / 黄 |
8. Reactions of Acids (General Equations) | 酸的反应通式
Acids follow predictable patterns when they react with certain substances. These general equations are extremely powerful - once you know the type of reactant, you can predict the products.
酸与特定物质反应时遵循可预测的规律。掌握这些通式非常有用——一旦知道反应物类型，你就能预测生成物。
Acid + Metal → Salt + Hydrogen
酸 + 金属 → 盐 + 氢气
id + zinc → zinc chloride + hydrogen. The salt takes its name from the metal and the acid.
示例：盐酸 + 锌 → 氯化锌 + 氢气。盐的名称由金属和酸根决定。
Acid + Metal Oxide → Salt + Water
酸 + 金属氧化物 → 盐 + 水
Neutralisation with a base: sulfuric acid + copper oxide → copper sulfate + water.
与碱的中和反应：硫酸 + 氧化铜 → 硫酸铜 + 水。
Acid + Metal Carbonate → Salt + Water + Carbon Dioxide
酸 + 金属碳酸盐 → 盐 + 水 + 二氧化碳
Fizzing (effervescence) is observed as CO₂ gas is produced. The test for carbon dioxide is bubbling through limewater, which turns milky.
当产生 CO₂ 气体时，可观察到冒泡（起泡）。检验二氧化碳的方法是将气体通入石灰水，石灰水变浑浊。
9. Separation Techniques | 分离技术
Mixtures can be separated using physical methods that depend on differences in properties such as boiling point, particle size or solubility.
混合物可以通过物理方法分离，这些方法依赖于沸点、粒子大小或溶解度等性质的差异。
Filtration separates an insoluble solid from a liquid. The solid stays on the filter paper (residue) while the liquid passes through (filtrate).
过滤用于分离不溶性固体和液体。固体留在滤纸上（残渣），液体通过滤纸（滤液）。
Evaporation removes the solvent from a solution, leaving the solid solute behind. Crystallisation produces large, pure crystals by gentle heating and cooling.
蒸发将溶液中的溶剂除去，留下固体溶质。结晶法通过缓慢加热和冷却获得大而纯净的晶体。
Distillation separates a liquid from a solution or a mixture of liquids with different boiling points. The liquid with the lower boiling point evaporates first, is then condensed and collected as the distillate.
蒸馏从溶液或沸点不同的液体混合物中分离出液体。沸点较低的液体首先蒸发，然后冷凝，以馏出液形式收集。
Chromatography separates dissolved substances as they travel at different speeds through a stationary phase. It is often used to separate coloured dyes or inks.
色谱法利用不同溶解物质在固定相中移动速度的差异实现分离。常用于分离有色染料或墨水。
10. Introduction to the Periodic Table | 元素周期表简介
The Periodic Table organises all known elements in order of increasing atomic number. Elements with similar chemical properties are placed in the same vertical column, called a group.
元素周期表按原子序数递增的顺序排列所有已知元素。化学性质相似的元素被放在同一纵列，称为族。
Horizontal rows are called periods. As you move across a period, the properties of elements change gradually from metallic to non-metallic.
横排称为周期。在同一周期中，从左至右元素的性质逐渐从金属性变为非金属性。
Metals are on the left and centre; non-metals are on the right. The dividing line often starts near boron (B) and steps down to polonium (Po). Group 1 contains very reactive alkali metals; Group 7 contains reactive halogens; Group 0 (or 8) contains unreactive noble gases.
金属位于左侧和中间，非金属位于右侧。分界线通常从硼（B）附近开始，阶梯延伸到钋（Po）。第 1 族是极活泼的碱金属；第 7 族是活泼的卤素；第 0 族（或第 8 族）是惰性的稀有气体。
Knowing an element's position helps you predict its physical state at room temperature, its reactivity and the type of compounds it will form.
知道元素在周期表中的位置，有助于预测它在室温下的状态、活泼性以及会形成哪类化合物。
The arrangement of electrons in shells (2,8,8 for the first elements) underpins the Periodic Table's structure. This will be explored in more depth later.
电子按壳层排布（前几周期为 2,8,8）奠定了周期表结构的基础，后续学习将进一步深入。
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