📚 IGCSE Chemistry: Key Topics Summary | IGCSE 化学：关键考点归纳
This article provides a concise summary of the most important topics in IGCSE Chemistry. It is designed to help you review fundamental principles, common equations, and core concepts before your exams. Each section pairs English explanations with Chinese translations to support bilingual learners.
本文简明归纳了 IGCSE 化学中最关键的考点。旨在帮助你在考前回顾基本原理、常见方程式与核心概念。每个小节均以中英文对照呈现，便于双语学习者理解和记忆。
1. States of Matter and Changes of State | 物质状态与状态变化
Solid, liquid and gas are the three states of matter. Particles in a solid are tightly packed in a regular pattern and can only vibrate. In a liquid, particles are close together but can move past each other, allowing the liquid to flow. Gas particles are far apart and move randomly at high speeds. The kinetic particle theory explains these behaviours in terms of particle arrangement and energy.
物质有三种状态：固体、液体和气体。固体粒子紧密排列、位置固定，仅能振动；液体粒子相互靠近但可滑动，因此液体能够流动；气体粒子间距很大，快速无规则运动。粒子运动理论从粒子排列和能量的角度解释了这些性质。
Changes of state include melting, freezing, boiling, evaporation, condensation and sublimation. At the melting point or boiling point, the temperature stays constant even though heat is still being supplied, because the energy is used to overcome the forces between particles rather than to raise the kinetic energy. Evaporation differs from boiling: it occurs only at the surface and can happen at any temperature below the boiling point.
状态变化包括熔化、凝固、沸腾、蒸发、凝结和升华。在熔点或沸点时，尽管持续加热，温度却保持不变，因为此时能量用于克服粒子间作用力，而不是增加动能。蒸发不同于沸腾：它只发生在液体表面，且在低于沸点的任何温度下均可发生。
Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. The rate of diffusion is higher in gases than in liquids, and increases with temperature because particles have more kinetic energy. A smaller relative molecular mass also leads to faster diffusion.
扩散是粒子从高浓度区域向低浓度区域的运动。气体中的扩散速率高于液体，且随温度升高而加快，因为粒子动能增大。相对分子质量较小也会使扩散更快。
2. Atomic Structure and the Periodic Table | 原子结构与周期表
An atom consists of a nucleus containing protons and neutrons, surrounded by electrons arranged in shells. Protons are positively charged, neutrons are neutral, and electrons are negatively charged. The atomic number (Z) is the number of protons, which determines the element. The mass number (A) is the total number of protons and neutrons. Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
原子由含质子和中子的原子核以及核外分层排布的电子构成。质子带正电，中子不带电，电子带负电。原子序数 (Z) 等于质子数，决定了元素的种类。质量数 (A) 是质子数和中子数之和。同位素是质子数相同而中子数不同的同种元素原子。
Electrons occupy specific energy levels or shells. The first shell holds up to 2 electrons, the second up to 8, and the third up to 8 in the IGCSE model. The electronic configuration of an element determines its chemical properties and its position in the Periodic Table. The valency electrons are those in the outermost shell.
电子填充在特定的电子层。第一层最多容纳 2 个电子，第二层最多 8 个，第三层最多 8 个（IGCSE 模型）。元素的电子排布决定其化学性质和它在周期表中的位置。最外层的电子为价电子。
The Periodic Table arranges elements in order of increasing atomic number. Groups are vertical columns; elements in the same group have the same number of outer electrons and similar chemical properties. Periods are horizontal rows; across a period the number of outer electrons increases. Metals are on the left and centre, non-metals on the right. Group 1 alkali metals are very reactive, Group 7 halogens are reactive non-metals, and Group 0 noble gases are unreactive due to full outer shells.
周期表按原子序数递增的顺序排列元素。族是纵列；同族元素最外层电子数相同，化学性质相似。周期是横行；同一周期从左到右最外层电子数增加。金属位于左侧和中部，非金属在右侧。第 1 族碱金属非常活泼，第 7 族卤素是活泼非金属，第 0 族稀有气体因最外层填满而极不活泼。
3. Chemical Bonding and Structure | 化学键与结构
Atoms bond together to achieve a stable electronic configuration, usually that of a noble gas. The three main types of bonding are ionic, covalent and metallic. Ionic bonding occurs between a metal and a non-metal. The metal atom loses electrons to become a positive ion (cation), while the non-metal atom gains electrons to become a negative ion (anion). The oppositely charged ions are held together by strong electrostatic forces of attraction in a giant ionic lattice.
原子通过化学键结合以达到稳定的电子构型，通常为稀有气体结构。三种主要化学键类型为离子键、共价键和金属键。离子键形成于金属与非金属之间。金属原子失去电子成为阳离子，非金属原子得到电子成为阴离子。带相反电荷的离子在巨型离子晶格中通过强静电引力结合在一起。
Ionic compounds have high melting and boiling points because a large amount of energy is needed to break the strong ionic bonds throughout the lattice. They conduct electricity when molten or dissolved in water because the ions become free to move, but do not conduct when solid. They are often soluble in water and form crystals.
离子化合物具有高熔点和高沸点，因为需要大量能量来破坏整个晶格中的强离子键。它们在熔融或溶于水时能导电，因为离子可自由移动；但在固态时不导电。它们通常可溶于水，形成晶体。
Covalent bonding occurs between non-metal atoms. The atoms share pairs of electrons to gain full outer shells. Covalent bonds can form simple molecular structures (such as H₂O, CO₂, CH₄) with weak intermolecular forces and low melting points, or giant covalent structures (such as diamond, graphite, silicon dioxide) with very high melting points. Graphite conducts electricity because each carbon atom has one delocalised electron; diamond does not conduct as all electrons are used in bonds.
共价键形成于非金属原子之间。原子通过共享电子对来获得满壳层。共价键可形成简单分子结构（如 H₂O、CO₂、CH₄），分子间作用力弱，熔点低；或形成巨型共价结构（如金刚石、石墨、二氧化硅），熔点极高。石墨能导电，因为每个碳原子有一个离域电子；金刚石的所有电子都用于成键，故不导电。
Metallic bonding is the attraction between positive metal ions and a sea of delocalised electrons. This structure allows metals to conduct electricity and heat, be malleable and ductile, and have high melting points (though some, like mercury, are liquids). Alloys are mixtures of metals with other elements, which disrupt the regular lattice and make the material harder and less malleable.
金属键是金属阳离子与离域电子海之间的吸引力。这种结构使金属能够导电导热、具有延展性和高熔点（尽管有些如汞为液态）。合金是金属与其他元素的混合物，扰乱了规则的晶格，使材料更硬、延展性降低。
4. Stoichiometry and the Mole Concept | 化学计量与摩尔概念
The relative atomic mass (Aᵣ) of an element is the average mass of its atoms compared to 1/12 of the mass of a carbon‑12 atom. Relative molecular/formula mass (Mᵣ) is the sum of the Aᵣ of all atoms in a formula. One mole of a substance contains 6.02 × 10²³ particles (Avogadro constant). The mass of one mole of a substance in grams is equal to its Mᵣ.
元素的相对原子质量 (Aᵣ) 是其原子平均质量与碳‑12 原子质量的 1/12 之比。相对分子/式量 (Mᵣ) 是一个化学式中所有原子的 Aᵣ 之和。一摩尔物质含有 6.02 × 10²³ 个粒子（阿伏伽德罗常数）。一摩尔物质的质量（以克计）等于其 Mᵣ。
The amount of substance (in mol) can be calculated from mass and molar mass: n = m / M. For gases at room temperature and pressure (r.t.p.), one mole occupies 24 dm³. The concentration of a solution in mol dm⁻³ is given by: c = n / V (where V is in dm³). Percentage yield, empirical formula and molecular formula calculations are essential skills.
物质的量（摩尔）可由质量和摩尔质量计算：n = m / M。在室温常压下，一摩尔气体体积为 24 dm³。溶液的浓度（mol dm⁻³）为：c = n / V（V 单位为 dm³）。产率、实验式和分子式的计算是必备技能。
Empirical formula is the simplest whole‑number ratio of atoms in a compound, found from experimental mass or percentage data. Molecular formula is a multiple of the empirical formula, determined using Mᵣ. Balancing chemical equations ensures that the number of atoms of each element is conserved.
实验式是化合物中各原子的最简整数比，可通过实验质量或百分含量求得。分子式是实验式的整数倍，利用 Mᵣ 确定。配平化学方程式确保各元素原子数守恒。
5. Chemical Reactions and Energy Changes | 化学反应与能量变化
Chemical reactions involve the rearrangement of atoms. Signs of a chemical change include colour change, gas evolution, precipitate formation, and temperature change. Exothermic reactions release heat energy to the surroundings (temperature increases), while endothermic reactions absorb heat energy (temperature decreases). Bond breaking is endothermic; bond making is exothermic.
化学反应涉及原子的重新排列。化学变化的标志包括颜色变化、气体产生、沉淀生成和温度变化。放热反应向环境释放热量（温度升高），吸热反应吸收热量（温度降低）。断键需吸热，成键则放热。
Enthalpy change (ΔH) can be measured by simple calorimetry. Energy released or absorbed can be calculated using q = mcΔT, where m is mass of solution, c is specific heat capacity (usually 4.2 J g⁻¹ °C⁻¹ for water), and ΔT is temperature change. Then divide by moles to find ΔH in kJ mol⁻¹. Common exothermic reactions include combustion, neutralisation and displacement. Photosynthesis and thermal decomposition are endothermic.
焓变 (ΔH) 可通过简单量热法测定。释放或吸收的能量可用 q = mcΔT 计算，m 为溶液质量，c 为比热容（水通常取 4.2 J g⁻¹ °C⁻¹），ΔT 为温度变化。再除以物质的量即得 ΔH (kJ mol⁻¹)。燃烧、中和和置换反应通常是放热的；光合作用和热分解是吸热的。
Reaction rate is affected by concentration, temperature, surface area of solids, and use of catalysts. Increasing concentration, temperature or surface area increases the frequency of successful collisions, increasing the rate. Catalysts provide an alternative pathway with lower activation energy, speeding up both forward and backward reactions without being used up. Understanding collision theory is key.
反应速率受浓度、温度、固体表面积和催化剂影响。提高浓度、温度或增大表面积可增加有效碰撞频率，从而提高反应速率。催化剂提供活化能较低的替代路径，同时加速正逆反应而自身不被消耗。碰撞理论是理解这些影响的关键。
6. Acids, Bases, Salts and pH | 酸、碱、盐与 pH
An acid is a substance that produces hydrogen ions (H⁺) in water. A base is a substance that reacts with an acid to form a salt and water; an alkali is a soluble base that produces hydroxide ions (OH⁻) in water. Common acids include hydrochloric acid (HCl), sulfuric acid (H₂SO₄) and nitric acid (HNO₃). Common alkalis are sodium hydroxide (NaOH), potassium hydroxide (KOH) and ammonia solution (NH₃).
酸是在水中产生氢离子 (H⁺) 的物质。碱是与酸反应生成盐和水的物质；可溶的碱称为碱，它在水中产生氢氧根离子 (OH⁻)。常见酸有盐酸 (HCl)、硫酸 (H₂SO₄) 和硝酸 (HNO₃)。常见碱有氢氧化钠 (NaOH)、氢氧化钾 (KOH) 和氨水 (NH₃)。
The pH scale (0 to 14) measures the acidity or alkalinity of a solution. A pH less than 7 is acidic, pH 7 is neutral, pH greater than 7 is alkaline. Universal indicator or a pH meter can be used. Indicators like litmus, methyl orange and phenolphthalein show colour changes at specific pH ranges.
pH 标度 (0–14) 用于衡量溶液的酸碱性。pH < 7 为酸性，pH = 7 为中性，pH > 7 为碱性。可使用通用指示剂或 pH 计测定。石蕊、甲基橙和酚酞等指示剂在特定 pH 范围内变色。
Neutralisation reaction: acid + base → salt + water. The ionic equation is H⁺ + OH⁻ → H₂O. Neutralisation releases heat. Salts can be prepared by several methods: titration (for soluble salts of Group 1, ammonium salts), reaction of acid with excess metal, insoluble base or carbonate, followed by filtration and crystallisation. Precipitation can be used for insoluble salts.
中和反应：酸 + 碱 → 盐 + 水。离子方程式为 H⁺ + OH⁻ → H₂O。中和放热。盐的制备方法有多种：滴定法（适用于可溶的第 1 族盐、铵盐）；酸与过量金属、不溶性碱或碳酸盐反应，然后过滤、结晶。沉淀法用于制取不溶性盐。
7. Metals, Reactivity and Extraction | 金属、活泼性与冶炼
The reactivity series orders metals from most reactive to least reactive: K, Na, Ca, Mg, Al, (C), Zn, Fe, (H), Cu, Ag, Au. Carbon and hydrogen are included for reference in extraction and displacement. A more reactive metal displaces a less reactive metal from its compound. Metals react with water or steam at varying rates, and with dilute acids to produce hydrogen gas and a salt.
金属活动性顺序从活泼到不活泼依次为：K、Na、Ca、Mg、Al、(C)、Zn、Fe、(H)、Cu、Ag、Au。碳和氢作为参考纳入。较活泼的金属能将较不活泼的金属从其化合物中置换出来。金属与水或蒸汽反应速率各异，与稀酸反应产生氢气和盐。
Extraction methods depend on the metal’s position in the reactivity series. Metals above carbon are extracted by electrolysis of their molten ores (e.g. aluminium from aluminium oxide). Metals below carbon can be extracted by reduction of their oxides with carbon (e.g. iron from iron oxide in a blast furnace). Unreactive metals like gold are found native. Aluminium extraction requires cryolite to lower the melting point of aluminium oxide.
冶炼方法取决于金属在活动性顺序表中的位置。比碳活泼的金属通过电解熔融矿石提取（如电解氧化铝制铝）。不如碳活泼的金属可用碳还原其氧化物（如高炉中用氧化铁炼铁）。金等不活泼金属以天然单质存在。铝冶炼需要冰晶石来降低氧化铝的熔点。
Alloys are mixtures of metals, often designed to have improved properties. Steels are alloys of iron with carbon and other elements. Stainless steel contains chromium and nickel, which resist corrosion. The uses of metals relate to their properties: aluminium is light and resistant to corrosion; copper is a good conductor; iron/steel is strong.
合金是金属的混合物，旨在改善性能。钢是铁与碳等元素的合金。不锈钢含铬和镍，具有抗腐蚀性。金属的用途与其性质相关：铝质轻且抗腐蚀；铜是良导体；铁/钢强度高。
8. Electrolysis and Electrochemistry | 电解与电化学
Electrolysis is the decomposition of an ionic compound, when molten or in solution, by passing an electric current through it. The electrolyte is the substance undergoing electrolysis; the electrodes are usually inert (graphite or platinum). The positive electrode is the anode, where oxidation (loss of electrons) occurs; the negative electrode is the cathode, where reduction (gain of electrons) occurs.
电解是利用电流使处于熔融态或溶液中的离子化合物分解的过程。电解质是发生电解的物质；电极通常为惰性材料（石墨或铂）。正极为阳极，发生氧化（失去电子）；负极为阴极，发生还原（得到电子）。
In molten electrolytes, the metal cation moves to the cathode and gains electrons to form the pure metal; the anion moves to the anode and loses electrons to form the non-metal. In aqueous solutions, the products depend on the relative ease of discharge of ions and the concentration of the solution. At the cathode, the less reactive metal or hydrogen is produced; at the anode, if halide ions are present they are discharged, otherwise oxygen is produced from OH⁻ ions. This can be remembered using the preferential discharge series.
在熔融电解质中，金属阳离子移向阴极，得电子生成纯金属；阴离子移向阳极，失电子生成非金属。在水溶液中，产物取决于离子的放电顺序和溶液浓度。在阴极，较不活泼的金属或氢气析出；在阳极，若存在卤离子则优先放电，否则氢氧根离子放电产生氧气。此规则可借助放电顺序记忆。
Electrolysis has important industrial applications: extraction of aluminium from bauxite; purification of copper (impure copper anode, pure copper cathode, CuSO₄ electrolyte); electroplating of silver, gold or chromium onto objects. In simple cells, two different metals in an electrolyte produce a voltage; the greater the difference in reactivity, the larger the voltage. A hydrogen fuel cell generates electricity by reacting hydrogen and oxygen, with water as the only product.
电解有重要的工业应用：从铝土矿中提取铝；精炼铜（粗铜为阳极，纯铜为阴极，硫酸铜为电解液）；在物体上电镀银、金或铬。在简单电池中，两种不同金属放入电解液即产生电压；金属活泼性差异越大，电压越大。氢燃料电池通过氢和氧的反应发电，唯一产物为水。
9. Chemical Analysis and Identification | 化学分析与鉴定
Qualitative analysis involves identifying substances present. Tests for gases: hydrogen gives a squeaky pop with a lighted splint; oxygen relights a glowing splint; carbon dioxide turns limewater milky; chlorine bleaches damp litmus paper; ammonia turns red litmus blue and has a pungent smell.
定性分析用于鉴定物质。气体检验：氢气遇点燃的火柴发出爆鸣声；氧气使带火星木条复燃；二氧化碳使石灰水变浑浊；氯气使湿润石蕊试纸漂白；氨气具有刺激性气味并使红色石蕊试纸变蓝。
Flame tests identify metal ions: lithium (red), sodium (yellow/orange), potassium (lilac), calcium (brick red), copper (blue-green). Adding sodium hydroxide solution and warming can test for ammonium ions (ammonia gas released). Other cation tests involve adding NaOH and observing precipitate colour and solubility in excess NaOH: Cu²⁺ (blue ppt), Fe²⁺ (green ppt), Fe³⁺ (brown ppt), Ca²⁺ (white ppt, insoluble in excess), Al³⁺ (white ppt, soluble in excess), Zn²⁺ (white ppt, soluble in excess).
焰色试验可鉴定金属离子：锂（红色）、钠（黄色/橙色）、钾（紫色）、钙（砖红色）、铜（蓝绿色）。加入氢氧化钠溶液并微热可检验铵离子（释放氨气）。其他阳离子检验方法是加入 NaOH 观察沉淀颜色及其在过量 NaOH 中的溶解性：Cu²⁺（蓝色沉淀）、Fe²⁺（绿色沉淀）、Fe³⁺（棕色沉淀）、Ca²⁺（白色沉淀，不溶于过量 NaOH）、Al³⁺（白色沉淀，可溶）、Zn²⁺（白色沉淀，可溶）。
Anion tests: carbonates CO₃²⁻ react with acid to give CO₂; halide ions Cl⁻, Br⁻, I⁻ are tested with nitric acid and silver nitrate – white precipitate (AgCl), cream precipitate (AgBr), yellow precipitate (AgI); sulfates SO₄²⁻ are tested with hydrochloric acid and barium chloride – white precipitate of BaSO₄; nitrates can be tested with aluminium and NaOH to produce ammonia on warming.
阴离子检验：碳酸根 CO₃²⁻ 遇酸产生 CO₂；卤素离子 Cl⁻、Br⁻、I⁻ 用硝酸和硝酸银检验——产生白色沉淀 (AgCl)、淡黄色沉淀 (AgBr)、黄色沉淀 (AgI)；硫酸根 SO₄²⁻ 用盐酸和氯化钡检验——生成白色 BaSO₄ 沉淀；硝酸根可用铝和 NaOH 并加热，产生氨气。
10. Organic Chemistry Fundamentals | 有机化学基础
Organic chemistry is the study of carbon compounds, including hydrocarbons and their derivatives. Alkanes are saturated hydrocarbons with the general formula CₙH₂ₙ₊₂. They are relatively unreactive but undergo combustion and substitution reactions with halogens in UV light. Alkenes contain a C=C double bond (unsaturated) with formula CₙH₂ₙ. They undergo addition reactions, turning bromine water from orange to colourless, a test for unsaturation.
有机化学研究碳化合物，包括碳氢化合物及其衍生物。烷烃是饱和烃，通式为 CₙH₂ₙ₊₂。它们相对不活泼，但能发生燃烧和在紫外光下与卤素的取代反应。烯烃含 C=C 双键（不饱和），通式为 CₙH₂ₙ，能发生加成反应，使溴水由橙黄色变为无色，这可用于检验不饱和键。
Alcohols contain the –OH functional group. Ethanol can be produced by fermentation of glucose (yeast, 30–37 °C, anaerobic) or by hydration of ethene with steam and a phosphoric acid catalyst. Oxidation of ethanol produces ethanoic acid. Carboxylic acids contain the –COOH group; they are weak acids, react with alcohols to form esters in the presence of an acid catalyst (esterification). Esters have fruity smells and are used in flavourings and solvents.
醇类含官能团 –OH。乙醇可通过葡萄糖发酵（酵母，30–37 °C，厌氧）或乙烯与蒸汽在磷酸催化下水合制取。乙醇氧化生成乙酸。羧酸含 –COOH 基团，为弱酸；在酸催化下与醇反应生成酯（酯化反应）。酯具有果香，用作香料和溶剂。
Polymers are large molecules made by joining small monomer units. Addition polymers are formed from alkenes, e.g. poly(ethene), poly(propene). Condensation polymers such as polyesters and polyamides (nylons) are formed with elimination of a small molecule like water. Plastics have many uses but pose environmental problems due to non‑biodegradability. Biodegradable polymers and recycling help address this.
聚合物是由小分子单体聚合而成的大分子。加成聚合物由烯烃加聚得到，如聚乙烯、聚丙烯。缩聚聚合物如聚酯和聚酰胺（尼龙），形成时脱去小分子（如水）。塑料用途广泛，但因不可生物降解而带来环境问题。可生物降解的聚合物和回收利用有助于解决此问题。
11. Equilibrium and Haber Process | 平衡与哈伯过程
A reversible reaction is one where the reaction can proceed in both the forward and backward directions. At equilibrium, the rates of the forward and backward reactions are equal, and the concentrations of reactants and products remain constant (dynamic equilibrium). The conditions for a closed system are required.
可逆反应是指正反两个方向都能进行的反应。达到平衡时，正逆反应速率相等，反应物和生成物的浓度保持恒定（动态平衡）。这需要一个封闭系统。
Le Chatelier’s principle states that if a system at equilibrium is subjected to a change in concentration, temperature or pressure, the equilibrium shifts to oppose the change. Increasing concentration of a reactant favours the forward reaction; increasing temperature favours the endothermic direction; increasing pressure favours the side with fewer gas molecules.
勒夏特列原理指出，若改变平衡系统的浓度、温度或压强，平衡将向着减弱该改变的方向移动。增加反应物浓度有利于正反应；升高温度有利于吸热方向；增大压强有利于气体分子数较少的一侧。
The Haber process manufactures ammonia from nitrogen and hydrogen: N₂ + 3H₂ ⇌ 2NH₃, ΔH = −92 kJ mol⁻¹. The optimum conditions are 450 °C, 200 atm, and an iron catalyst. These are a compromise: lower temperature would shift equilibrium to give a higher yield of NH₃ but make the rate too slow; high pressure favours the forward reaction (4 moles gas → 2 moles) but is costly. The catalyst speeds up the reaction without affecting the equilibrium position. Ammonia is used to make fertilisers, nitric acid and explosives.
哈伯过程用氮气和氢气合成氨：N₂ + 3H₂ ⇌ 2NH₃，ΔH = −92 kJ mol⁻¹。最佳条件为 450 °C、200 大气压和铁催化剂。这是一个折中方案：较低温度可使平衡向生成更多氨的方向移动，但反应速率太慢；高压有利于正反应（4 分子气体 → 2 分子），但设备成本高。催化剂加快反应速率而不影响平衡位置。氨用于制造化肥、硝酸和炸药。
12. Environmental Chemistry and Practical Skills | 环境化学与实验技能
Air is a mixture of gases: approximately 78% nitrogen, 21% oxygen, with small amounts of CO₂, argon and water vapour. Combustion of fossil fuels produces carbon dioxide, which contributes to global warming, and sulfur dioxide and nitrogen oxides, which cause acid rain. Carbon monoxide is a toxic gas produced by incomplete combustion. Catalytic converters in cars reduce these pollutants.
空气是气体混合物：约 78% 氮气、21% 氧气，以及少量 CO₂、氩气和水蒸气。化石燃料燃烧产生二氧化碳（导致全球变暖）、二氧化硫和氮氧化物（引起酸雨）。一氧化碳是不完全燃烧产生的有毒气体。汽车催化转化器可减少这些污染物。
Water treatment involves filtration, sedimentation and chlorination to make water safe to drink. Water pollution from nitrates (eutrophication), heavy metals and untreated sewage must be managed. Sustainable chemistry and the use of renewable resources are increasingly important. The carbon cycle and nitrogen cycle are fundamental biogeochemical processes.
水处理包括过滤、沉淀和氯化消毒，使水可安全饮用。硝酸盐（富营养化）、重金属和未处理污水造成的水污染必须加以管理。绿色化学和可再生资源的利用日益重要。碳循环和氮循环是基本的生物地球化学过程。
Practical skills for IGCSE include measurement of temperature, mass, volume and time; recording and presenting data in tables and graphs; identifying sources of error and suggesting improvements; conducting flame tests and ion identification; titrations; preparation of salts; and filtration, evaporation, crystallisation and distillation. Safety precautions and proper handling of chemicals are essential.
IGCSE 实验技能包括测量温度、质量、体积和时间；以表格和图表记录并呈现数据；识别误差来源并提出改进方法；进行焰色试验和离子鉴定；滴定操作；盐的制备；以及过滤、蒸发、结晶和蒸馏。安全预防措施和正确使用化学品至关重要。
Published by TutorHao | Chemistry Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导