📚 Year 7 SQA Chemistry: Quick Reference Handbook of Formulas and Principles | SQA 化学：公式定理速查手册（Year 7）
This quick reference handbook brings together the essential formulas, rules and principles you need for Year 7 SQA Chemistry. From the particle model of matter to balancing equations and exploring acids and alkalis, every key idea is presented as a concise statement with paired English and Chinese explanations. Use it to revise for class tests, complete homework, or simply check your understanding of the foundations of chemistry.
这份速查手册汇集了 Year 7 SQA 化学所需的核心公式、规则和原理。从物质的粒子模型到方程式配平，再到酸与碱的探索，每一条关键知识都以简洁的陈述形式呈现，并配有英文和中文双语解释。你可以用它来准备课堂测验、完成家庭作业，或者随时检验自己对化学基础的理解。
1. Law of Conservation of Mass | 质量守恒定律
In a chemical reaction, the total mass of the reactants is always equal to the total mass of the products. No atoms are created or destroyed; they are simply rearranged.
在化学反应中，反应物的总质量始终等于生成物的总质量。原子不会凭空产生或消失，它们只是重新组合排列。
This means that if you measure the mass of everything before a reaction and again after it, the numbers will match exactly – provided nothing escapes into the surroundings.
这意味着如果你在反应前后测量所有物质的质量，数值将会完全相等——前提是没有任何物质逸散到周围环境中。
2. Particle Model of Matter | 物质的粒子模型
All matter is made of tiny, moving particles. The arrangement and movement of these particles determine whether a substance is a solid, liquid or gas.
所有物质都由不断运动的微小粒子构成。粒子的排列方式和运动状态决定了物质是固体、液体还是气体。
In solids, particles are packed closely in a fixed pattern and only vibrate; in liquids, particles are close together but can slide past each other; in gases, particles are far apart and move rapidly in all directions.
在固体中，粒子紧密排列成固定结构，只能振动；在液体中，粒子彼此靠近但可以滑动；在气体中，粒子相距很远，朝各个方向快速运动。
3. Simple Atomic Structure | 简单的原子结构
An atom consists of a central nucleus containing protons and neutrons, surrounded by electrons orbiting in shells. Protons carry a positive charge, electrons carry a negative charge, and neutrons have no charge.
原子由一个含有质子和中子的中心原子核以及绕核分层排布的电子组成。质子带正电，电子带负电，中子不带电。
The number of protons (the atomic number) defines which element an atom belongs to. In a neutral atom, the number of electrons equals the number of protons.
质子数（原子序数）决定了原子属于哪种元素。在中性原子中，电子数等于质子数。
4. Electron Shell Filling Rules (First 20 Elements) | 电子层填充规则（前20号元素）
Electrons occupy shells around the nucleus. The first shell can hold up to 2 electrons, the second shell up to 8 electrons, and the third shell also up to 8 electrons for the first 20 elements.
电子占据原子核外的电子层。第一层最多容纳 2 个电子，第二层最多容纳 8 个电子，对于前 20 号元素，第三层也最多容纳 8 个电子。
Electrons fill the lowest energy shells first. For example, oxygen (atomic number 8) has an electronic configuration of 2,6.
电子优先填充低能级电子层。例如，氧（原子序数 8）的电子排布为 2,6。
5. Writing Chemical Formulas – The Cross‑Over Method | 书写化学式——交叉相乘法
When two elements combine to form a compound, the charges on their ions must balance. Use the cross‑over method: write the symbol of each ion, swap the numerical value of their charges, and write them as subscripts.
当两种元素结合形成化合物时，它们离子的电荷必须平衡。使用交叉相乘法：写出每种离子的符号，交换电荷的数值，并把它们作为下标。
For example, aluminium (Al³⁺) and oxide (O²⁻) give Al₂O₃. The 3 from aluminium becomes the subscript for oxygen, and the 2 from oxygen becomes the subscript for aluminium.
例如，铝离子（Al³⁺）和氧离子（O²⁻）结合得到 Al₂O₃。铝的电荷数 3 成为氧的下标，氧的电荷数 2 成为铝的下标。
6. Naming Compounds | 化合物的命名规则
A compound made from two elements has a name ending in ‘-ide’. A compound containing a metal, a non‑metal and oxygen often ends in ‘-ate’ or ‘-ite’.
由两种元素组成的化合物名称以“-ide”结尾。含有金属、非金属和氧的化合物名称通常以“-ate”或“-ite”结尾。
Sodium chloride (NaCl) is the ‘-ide’ of sodium and chlorine. Copper sulfate (CuSO₄) is the ‘-ate’ from copper, sulfur and oxygen. The ‘-ite’ ending indicates one less oxygen atom than the ‘-ate’, e.g. sodium sulfite (Na₂SO₃).
氯化钠（NaCl）是钠和氯的“-ide”。硫酸铜（CuSO₄）是铜、硫和氧组成的“-ate”。“-ite”结尾表示比对应的“-ate”少一个氧原子，例如亚硫酸钠（Na₂SO₃）。
7. State Symbols in Equations | 方程式中的状态符号
Balanced chemical equations use state symbols in brackets to show the physical state of each substance: (s) for solid, (l) for liquid, (g) for gas, and (aq) for aqueous solution (dissolved in water).
配平的化学方程式使用括号内的状态符号表示每种物质的物理状态：(s) 表示固体，(l) 表示液体，(g) 表示气体，(aq) 表示水溶液（溶于水）。
(aq) + H₂(g). State symbols help chemists communicate precisely how a reaction is carried out.
例如：2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)。状态符号帮助化学家精确地传达反应是如何进行的。
8. Balancing Chemical Equations | 化学方程式配平
An equation must have the same number of each type of atom on both sides. Balance equations by placing whole numbers (coefficients) in front of the formulas – never change the subscripts inside a formula.
方程式两边每种原子的数目必须相等。通过在化学式前面放置整数（系数）来配平——切勿改动化学式内部的下标。
in front of H₂ and a 2 in front of H₂O: 2H₂ + O₂ → 2H₂O. Check: 4 H and 2 O on each side.
配平 H₂ + O₂ → H₂O 时，在 H₂ 前面放 2，在 H₂O 前面放 2：2H₂ + O₂ → 2H₂O。检查：每边各有 4 个 H 原子和 2 个 O 原子。
9. pH Scale and Universal Indicator | pH 标度与通用指示剂
The pH scale (0–14) measures how acidic or alkaline a solution is. pH values below 7 are acidic, pH 7 is neutral, and values above 7 are alkaline.
pH 标度（0–14）用于衡量溶液的酸碱度。pH 值小于 7 为酸性，pH 7 为中性，大于 7 为碱性。
Universal indicator gives a range of colours across the pH scale: red for strong acids, green for neutral, and purple for strong alkalis. Each step on the scale represents a tenfold change in acidity or alkalinity.
通用指示剂在整个 pH 标度上显示一系列颜色：强酸呈红色，中性呈绿色，强碱呈紫色。标度上每变化 1 个单位，酸碱度就相差 10 倍。
10. Neutralisation Reaction | 中和反应
i to produce a salt and water. The general word equation is: acid + alkali → salt + water.
酸与碱反应生成盐和水。一般的文字方程式为：酸 + 碱 → 盐 + 水。
(aq) + NaOH(aq) → NaCl(aq) + H₂O(l). The pH moves towards 7 as neutralisation takes place.
例如，盐酸与氢氧化钠反应生成氯化钠和水：HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)。随着中和反应的进行，pH 值趋向于 7。
11. Reactivity Series (Metals) | 金属活动性顺序
The reactivity series lists metals in order of how vigorously they react. A more reactive metal can displace a less reactive metal from its compound.
活动性顺序按照金属反应的剧烈程度排列。较活泼的金属可以把较不活泼的金属从其化合物中置换出来。
A simple mnemonic for the order: Potassium, Sodium, Calcium, Magnesium, Aluminium, (Carbon), Zinc, Iron, (Hydrogen), Copper, Silver, Gold. Carbon and hydrogen are included for displacement comparisons.
一个简单的记忆顺序是：钾、钠、钙、镁、铝、（碳）、锌、铁、（氢）、铜、银、金。把碳和氢纳入顺序是为了比较置换反应。
12. Factors Affecting Reaction Rate | 影响反应速率的因素
The rate of a chemical reaction can be increased by: raising the temperature, increasing the concentration of a reactant (or pressure of gases), increasing the surface area of a solid, or adding a catalyst.
提高化学反应的速率可以通过：升高温度、增大反应物的浓度（或气体压强）、增大固体的表面积、或加入催化剂。
These factors give particles more energy or bring them into closer contact, so that successful collisions happen more often. A catalyst speeds up a reaction without being used up itself.
这些因素使粒子获得更多能量，或者使它们接触更紧密，从而增加有效碰撞的频率。催化剂能加快反应速率，而自身在反应后不消耗。
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