📚 Year 10 WJEC Chemistry: Core Concepts Revision | WJEC Year 10 化学核心知识点梳理
This article covers the essential topics in the WJEC Year 10 Chemistry syllabus, offering a structured overview of key concepts, from atomic structure to reaction rates. Each section pairs English and Chinese explanations to strengthen understanding and bilingual competence.
本文梳理了WJEC考试局Year 10化学学科的核心知识点，系统涵盖原子结构、化学键、酸碱反应、电解、反应速率等重要主题。每个知识点均以英中双语对照讲解，帮助学习者巩固理解并提升双语能力。
1. Atomic Structure and the Periodic Table | 原子结构与元素周期表
Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells. The atomic number equals the number of protons, while the mass number is the total of protons and neutrons. Electrons occupy specific energy levels: 2 in the first shell, 8 in the second, and 8 in the third for the first 20 elements.
原子由包含质子和中子的原子核以及核外电子构成。原子序数等于质子数，质量数是质子数与中子数之和。电子排布在特定的电子层中：第1层最多2个电子，第2层最多8个，前20号元素的第3层最多8个。
Elements are arranged in the Periodic Table in order of increasing atomic number. Groups (vertical columns) contain elements with the same number of outer electrons, which determines their chemical properties. Periods (horizontal rows) indicate the number of electron shells.
元素在周期表中按原子序数递增的顺序排列。族（纵列）中的元素具有相同的最外层电子数，这决定了它们的化学性质。周期（横行）表示电子层数。
The Periodic Table is divided into metals, non‑metals, and semi‑metals (metalloids). Group 1 are the alkali metals, Group 2 the alkaline earth metals, Group 7 the halogens, and Group 0 the noble gases. Transition metals lie between Groups 2 and 3.
周期表分为金属、非金属和半金属（准金属）。第1族为碱金属，第2族为碱土金属，第7族为卤素，第0族为稀有气体。过渡金属位于第2族与第3族之间。
2. Chemical Bonding: Ionic, Covalent, and Metallic | 化学键：离子键、共价键与金属键
Ionic bonding occurs between metals and non‑metals. Metal atoms lose electrons to form positive ions (cations), while non‑metal atoms gain electrons to form negative ions (anions). The strong electrostatic attraction between oppositely charged ions forms a giant ionic lattice. Ionic compounds have high melting points and conduct electricity when molten or dissolved.
离子键存在于金属与非金属之间。金属原子失去电子形成阳离子，非金属原子得到电子形成阴离子。带相反电荷离子间的强静电引力构成巨型离子晶格。离子化合物熔点高，在熔融或溶于水时可导电。
Covalent bonding involves the sharing of electron pairs between non‑metal atoms. Simple molecular substances like H₂O, CO₂, and NH₃ have strong covalent bonds within molecules but weak intermolecular forces between molecules, resulting in low melting and boiling points. They do not conduct electricity.
共价键涉及非金属原子之间共用电子对。简单的分子物质，如 H₂O、CO₂ 和 NH₃，分子内共价键强，但分子间作用力弱，因此熔点和沸点较低。它们不导电。
Metallic bonding consists of positive metal ions surrounded by a 'sea' of delocalised electrons. This structure allows metals to conduct electricity and heat, be malleable and ductile. Alloys are made by mixing other elements into a metal, disrupting the regular lattice and making the alloy harder.
金属键由正金属离子浸在“离域电子海洋”中构成。这种结构使金属能够导电、导热，并具有延展性。合金通过在金属中混入其他元素制得，这会打乱规则的晶格，使合金更硬。
3. Giant Covalent Structures | 巨型共价结构
Some non‑metal elements form giant covalent (macromolecular) structures. Diamond has each carbon atom bonded to four others in a tetrahedral arrangement, making it extremely hard, with a very high melting point, and it does not conduct electricity.
某些非金属元素形成巨型共价（高分子）结构。金刚石中每个碳原子与另外四个碳原子以四面体方式键合，使其极硬、熔点极高，且不导电。
Graphite consists of carbon atoms arranged in layers of hexagonal rings. Each carbon forms three covalent bonds, leaving one delocalised electron per atom. These delocalised electrons allow graphite to conduct electricity, while weak forces between layers enable them to slide, making graphite soft and slippery.
石墨由碳原子排列成六边形环层状结构。每个碳原子形成三个共价键，剩余一个离域电子。这种离域电子使石墨能导电，而层间微弱的力使其可滑动，因此石墨柔软且滑腻。
Silicon dioxide (silica, SiO₂) also has a giant covalent structure, similar to diamond, with each silicon bonded to four oxygens and each oxygen to two silicons. It is hard, has a high melting point, and does not conduct electricity.
二氧化硅（SiO₂）也具有巨型共价结构，类似金刚石，每个硅原子与四个氧原子键合，每个氧原子与两个硅原子键合。它硬度大、熔点高、不导电。
4. Writing Formulae and Balancing Equations | 化学式的书写与方程式配平
Chemical formulae show the types and numbers of atoms in a compound. For ionic compounds, the total positive charge must equal the total negative charge. For example, sodium chloride: Na⁺ and Cl⁻ give NaCl; magnesium oxide: Mg²⁺ and O²⁻ give MgO; aluminium oxide: Al³⁺ and O²⁻ give Al₂O₃.
化学式表示化合物中原子的种类和数目。对于离子化合物，正负电荷总数必须相等。例如，氯化钠：Na⁺ 与 Cl⁻ 得 NaCl；氧化镁：Mg²⁺ 与 O²⁻ 得 MgO；氧化铝：Al³⁺ 与 O²⁻ 得 Al₂O₃。
Word equations and balanced symbol equations represent chemical reactions. A balanced equation has the same number of each type of atom on both sides. State symbols: (s) solid, (l) liquid, (g) gas, (aq) aqueous solutions.
文字表达式和配平的符号方程式用于表示化学反应。配平后的方程式两边每种原子的数目相等。状态符号：(s) 固体，(l) 液体，(g) 气体，(aq) 水溶液。
e total mass of reactants equals the total mass of products (Law of Conservation of Mass).
例如：2Mg(s) + O₂(g) → 2MgO(s)。反应物的总质量等于生成物的总质量（质量守恒定律）。
5. The Mole Concept and Calculations | 物质的量（摩尔）概念与计算
constant). The molar mass (M) is the mass of one mole in grams per mole (g/mol), numerically equal to the relative atomic mass (Aᵣ) or relative formula mass (Mᵣ).
摩尔是物质的量的单位。1 摩尔任何物质含有 6.02 × 10²³ 个粒子（阿伏伽德罗常数）。摩尔质量（M）是 1 摩尔物质的质量，单位为 g/mol，数值上等于相对原子质量（Aᵣ）或相对式量（Mᵣ）。
number of moles (n) = mass (m) / molar mass (M)
核心关系式：n = m / M。由此可计算反应物和产物的质量。WJEC 还会涉及滴定和气体摩尔体积，但 Year 10 阶段主要掌握用摩尔计算物质质量和简单反应的计量关系。
Example: What mass of magnesium oxide forms when 4.8 g of magnesium burns in excess oxygen? tion 2Mg + O₂ → 2MgO shows a 1:1 mole ratio, so 0.2 mol MgO gives mass = 0.2 × 40 = 8.0 g.
使用摩尔可以计算反应质量。例：4.8 g 镁在过量氧气中燃烧，生成多少氧化镁？Mᵣ(MgO)=40，n(Mg)=4.8/24=0.2 mol。方程式 2Mg + O₂ → 2MgO 显示 1:1 摩尔比，因此 0.2 mol MgO 的质量 = 0.2×40=8.0 g。
6. Acids, Bases, and pH Scale | 酸、碱与pH值
Acids are substances that release hydrogen ions (H⁺) in water. Common acids: hydrochloric acid (HCl), sulfuric acid (H₂SO₄), nitric acid (HNO₃). The pH scale measures acidity or alkalinity: values below 7 are acidic, 7 is neutral, above 7 are alkaline.
酸是在水中能释放氢离子（H⁺）的物质。常见酸：盐酸 (HCl)、硫酸 (H₂SO₄)、硝酸 (HNO₃)。pH 标度衡量酸碱度：pH 小于 7 为酸性，7 为中性，大于 7 为碱性。
(NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)₂). The neutralisation reaction: H⁺(aq) + OH⁻(aq) → H₂O(l).
碱能中和酸生成盐和水。可溶性碱称为碱（alkali），在水中释放氢氧根离子 (OH⁻)。例如：氢氧化钠 (NaOH)、氢氧化钾 (KOH)、氢氧化钙 (Ca(OH)₂)。中和反应：H⁺(aq) + OH⁻(aq) → H₂O(l)。
Indicators change colour across the pH range. Litmus turns red in acid, blue in alkali. Universal indicator shows a spectrum of colours from red (strong acid) to purple (strong alkali).
指示剂在不同pH范围内变色。石蕊遇酸变红，遇碱变蓝。通用指示剂显示从红色（强酸）到紫色（强碱）的色谱。
7. Salts and their Preparation | 盐的制备
Salts are ionic compounds formed when the hydrogen of an acid is replaced by a metal or ammonium ion. Soluble salts can be prepared by reacting an acid with: a metal (for reactive metals, not too vigorous), a metal oxide (or hydroxide), or a metal carbonate.
盐是酸中的氢被金属或铵离子取代后形成的离子化合物。可溶性盐可通过酸与下列物质反应制备：金属（活泼金属但反应不宜过剧）、金属氧化物（或氢氧化物）或金属碳酸盐。
llising by evaporating some water and cooling. The equation: CuO(s) + H₂SO₄(aq) → CuSO₄(aq) + H₂O(l).
例如：将过量氧化铜加入温热的硫酸中，滤去多余固体，蒸发部分水分后冷却结晶，可得硫酸铜晶体。方程式：CuO(s) + H₂SO₄(aq) → CuSO₄(aq) + H₂O(l)。
ing solutions of barium chloride and sodium sulfate: BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq).
不溶性盐通过沉淀反应制备，混合两种含有目标离子的溶液即可。例如，硫酸钡可通过氯化钡溶液与硫酸钠溶液混合得到：BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)。
8. Electrolysis | 电解
Electrolysis is the decomposition of an ionic compound by passing an electric current through its molten state or aqueous solution. The positive anode attracts anions; the negative cathode attracts cations. At the electrodes, ions lose or gain electrons – oxidation at the anode, reduction at the cathode.
电解是将电流通过熔融态或水溶液中的离子化合物使其分解的过程。阳极（正极）吸引阴离子；阴极（负极）吸引阳离子。在电极上离子发生失得电子反应——阳极发生氧化，阴极发生还原。
hode produces lead metal (Pb²⁺ + 2e⁻ → Pb), anode produces bromine gas (2Br⁻ → Br₂ + 2e⁻).
电解熔融溴化铅：阴极生成金属铅 (Pb²⁺ + 2e⁻ → Pb)，阳极生成溴气 (2Br⁻ → Br₂ + 2e⁻)。
For aqueous solutions, water can also be oxidised or reduced. At the cathode: if the metal is more reactive than hydrogen, hydrogen gas is produced; if less reactive, the metal is discharged. At the anode: halide ions (Cl⁻, Br⁻, I⁻) are discharged as the halogen; otherwise, oxygen gas is produced from water.
在水溶液中，水也可以被氧化或还原。阴极：若金属比氢活泼，则产生氢气；若不如氢活泼，则金属单质析出。阳极：卤素离子（Cl⁻, Br⁻, I⁻）优先放电生成卤素单质；否则水放电产生氧气。
Electrolysis is used to extract reactive metals like aluminium from aluminium oxide (bauxite). The Hall‑Héroult process uses molten Al₂O₃ dissolved in cryolite to lower the melting point and save energy.
电解用于提炼活泼金属，如从氧化铝（铝土矿）中提取铝。霍尔‑埃鲁工艺将氧化铝溶解在冰晶石中以降低熔点并节约能源。
9. Energy Changes in Reactions | 反应中的能量变化
Chemical reactions involve energy transfer. Exothermic reactions release heat to the surroundings (temperature increases), e.g. combustion, neutralisation, and many oxidation reactions. Endothermic reactions absorb heat from the surroundings (temperature decreases), e.g. thermal decomposition of calcium carbonate and the reaction of citric acid and sodium hydrogencarbonate.
化学反应伴随能量转移。放热反应向环境释放热量（温度升高），如燃烧、中和和许多氧化反应。吸热反应从环境吸收热量（温度降低），如碳酸钙热分解和柠檬酸与碳酸氢钠的反应。
Reaction profiles show energy changes. In exothermic reactions, products have lower energy than reactants; in endothermic reactions, products are higher. The activation energy is the minimum energy required for a reaction to start.
反应过程图显示能量变化。放热反应中产物能量低于反应物；吸热反应中产物能量更高。活化能是引发反应所需的最低能量。
onds − energy released when forming bonds. If bond breaking energy is greater, the reaction is endothermic; if bond making releases more, it is exothermic.
断键吸热；成键放热。总能量变化 = 断键吸收的能量 − 成键释放的能量。若断键吸收的能量更大，则为吸热反应；反之则为放热反应。
10. Rate of Reaction | 反应速率
The rate of a reaction is the speed at which reactants are used up or products are formed. It can be measured by collecting a gas volume over time, measuring mass change, or observing the time for a change (e.g. colour change, precipitate appearance).
反应速率指反应物被消耗或产物生成的快慢。可通过收集气体体积随时间变化、测量质量变化或观察某一变化所需时间（如颜色变化、沉淀出现）来测量。
e particles per volume), surface area of solids (smaller particle size → greater surface area), and temperature (higher temperature → particles move faster and more collisions have energy ≥ activation energy).
影响反应速率的因素：溶液浓度（浓度越高，碰撞越频繁）、气体压强（压强越大，单位体积粒子数越多）、固体表面积（颗粒越小，表面积越大）和温度（温度越高，粒子运动越快，更多碰撞能量达到活化能）。
Catalysts increase the rate of reaction by providing an alternative pathway with a lower activation energy, without being used up. Enzymes are biological catalysts. A specific example: manganese(IV) oxide will catalyse the decomposition of hydrogen peroxide.
催化剂通过提供活化能较低的替代路径来提高反应速率，自身在反应前后保持不变。酶是生物催化剂。具体例子：二氧化锰催化过氧化氢分解。
11. Reactivity Series and Extraction of Metals | 金属活动性顺序与金属提炼
The reactivity series ranks metals by their tendency to form positive ions. For WJEC the order is: Potassium, Sodium, Calcium, Magnesium, Aluminium, Zinc, Iron, Tin, Lead, (Hydrogen), Copper, Silver, Gold. More reactive metals displace less reactive metals from their compounds.
金属活动性顺序根据金属形成阳离子的趋势排序。WJEC 常用顺序：钾、钠、钙、镁、铝、锌、铁、锡、铅、（氢）、铜、银、金。更活泼的金属可从化合物中置换出较不活泼的金属。
pper: Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s). Iron can also displace copper from its salts.
置换反应可用于比较活动性。例如，锌加入硫酸铜溶液中可置换出铜：Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s)。铁也能从铜盐溶液中置换出铜。
Extraction methods depend on a metal's reactivity. Metals below carbon in the series are extracted by reduction with carbon (e.g. iron from iron(III) oxide in a blast furnace). Metals above carbon (like potassium, sodium, calcium, magnesium, aluminium) are extracted by electrolysis of their molten compounds. Copper can be extracted by roasting its sulfide ore followed by reduction, then purified by electrolysis.
提炼方法取决于金属的活动性。活动性在碳之后的金属可用碳还原法提炼（如高炉中用一氧化碳还原氧化铁）。活动性在碳之前的金属（如钾、钠、钙、镁、铝）需通过电解其熔融化合物提炼。铜可通过焙烧硫化矿再还原得到，随后用电解法精炼。
12. Testing for Gases and Ions | 气体和常见离子的检验
WJEC Year 10 students must know simple tests for common gases: Oxygen relights a glowing splint; hydrogen gives a 'squeaky pop' with a lit splint; carbon dioxide turns limewater milky; chlorine bleaches damp litmus paper. Ammonia turns damp red litmus paper blue.
WJEC Year 10 学生需掌握常见气体的检验：氧气可使带火星的木条复燃；氢气在点燃的木条靠近时发出“咻”的爆鸣声；二氧化碳使石灰水变浑浊；氯气使湿润的蓝色石蕊试纸漂白。氨气使湿润的红色石蕊试纸变蓝。
Flame tests identify metal ions: lithium gives a crimson flame, sodium yellow, potassium lilac, calcium orange‑red, and copper green. Some cations form coloured precipitates with sodium hydroxide: Cu²⁺ pale blue, Fe²⁺ green, Fe³⁺ reddish‑brown. Al³⁺ and Zn²⁺ form white precipitates that dissolve in excess NaOH.
焰色反应可鉴别金属离子：锂呈洋红色，钠呈黄色，钾呈浅紫色，钙呈砖红色，铜呈绿色。某些阳离子与氢氧化钠溶液反应生成有色沉淀：Cu²⁺ 淡蓝色，Fe²⁺ 绿色，Fe³⁺ 红褐色。Al³⁺ 和 Zn²⁺ 则生成白色沉淀，并溶于过量 NaOH。
Anion tests: carbonates fizz with acid, producing CO₂ (test with limewater); halides (Cl⁻, Br⁻, I⁻) tested by adding dilute nitric acid followed by silver nitrate: chloride gives white precipitate, bromide cream, iodide yellow. Sulfate ions (SO₄²⁻) give a white precipitate with barium chloride after acidification with HCl.
阴离子检验：碳酸盐遇酸产生气泡并放出 CO₂（用石灰水检验）；卤素离子（Cl⁻, Br⁻, I⁻）先用稀硝酸酸化，再加硝酸银溶液：氯离子生成白色沉淀，溴离子浅黄色，碘离子黄色。硫酸根离子（SO₄²⁻）在酸化后与氯化钡溶液生成白色沉淀。
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