IB Chemistry: Last-Minute Revision Notes | IB 化学：考前冲刺笔记

📚 IB Chemistry: Last-Minute Revision Notes | IB 化学：考前冲刺笔记

These concise revision notes cover the core topics you need to master for the IB Chemistry examination. Each section pairs a quick English recap with its Chinese counterpart, highlighting definitions, equations, and common pitfalls. Use them to refresh your memory and reinforce key concepts in the final days before the test.

这份精简的冲刺笔记涵盖了 IB 化学考试必须掌握的核心主题。每个小节都采用英文快速回顾与中文配对的形式，突出定义、方程式和常见易错点。在考前最后几天用它来唤醒记忆、巩固关键概念。

1. Stoichiometric Relationships | 化学计量关系

The mole is the SI unit for amount of substance. One mole contains exactly 6.02214076 × 10²³ elementary entities (Avogadro’s number). The molar mass (M) is the mass of one mole of a substance, expressed in g mol⁻¹.

摩尔是物质的量的国际单位。1 摩尔恰好含有 6.02214076 × 10²³ 个基本单元（阿伏伽德罗常数）。摩尔质量 (M) 是一摩尔物质的质量，单位为 g mol⁻¹。

Key relationships: n = m / M, n = cV (for solutions), and for gases at STP (273 K, 100 kPa) the molar volume is 2.27 × 10⁻² m³ mol⁻¹ (or 22.7 dm³ mol⁻¹).

关键关系式：n = m / M，溶液用 n = cV，在标准状况（STP：273 K、100 kPa）下气体摩尔体积为 2.27 × 10⁻² m³ mol⁻¹（即 22.7 dm³ mol⁻¹）。

The empirical formula gives the simplest whole-number ratio of atoms in a compound; the molecular formula is a whole-number multiple of the empirical formula. Combustion analysis and percentage composition are typical tools for determining these formulas.

实验式给出化合物中原子最简整数比；分子式是实验式的整数倍。燃烧分析和元素百分含量是确定化学式的常用方法。

Always balance chemical equations to obey the law of conservation of mass. A balanced equation provides the mole ratios used in all stoichiometric calculations.

务必配平化学方程式以符合质量守恒定律。配平后的方程提供了所有化学计量计算所需的摩尔比。

2. Atomic Structure | 原子结构

Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in energy levels. The atomic number (Z) is the number of protons; the mass number (A) is the sum of protons and neutrons. Isotopes have the same Z but different A.

原子由包含质子和中子的原子核以及绕核分层排布的电子组成。原子序数 (Z) 是质子数；质量数 (A) 是质子数与中子数之和。同位素的 Z 相同而 A 不同。

The electromagnetic spectrum shows that energy is quantised. The hydrogen emission spectrum consists of discrete lines converging at higher energies, providing evidence for electron shells. The first ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous atoms.

电磁波谱显示能量是量子化的。氢原子发射光谱由一系列向高能端收敛的分立谱线组成，为电子层结构提供了证据。第一电离能是指从一摩尔气态原子中移去一摩尔电子所需的能量。

• n = 1, 2, 3… (principal quantum number, shell)
• Sub-levels: s, p, d, f
• Aufbau principle, Hund’s rule, Pauli exclusion principle

• n = 1, 2, 3… （主量子数，电子层）
• 亚层：s, p, d, f
• 构造原理、洪特规则、泡利不相容原理

3. Periodicity | 周期性

The periodic table arranges elements by increasing atomic number. Periods are horizontal rows; groups are vertical columns. Elements in the same group have similar outer electron configurations and therefore similar chemical properties.

元素周期表按原子序数递增排列。横行称为周期，纵列称为族。同族元素具有相似的外层电子排布，因而化学性质相似。

Trends across a period: atomic radius decreases, ionisation energy generally increases, electronegativity increases. Down a group: atomic radius increases, ionisation energy decreases, electronegativity decreases.

同周期递变规律：原子半径减小，电离能总体增大，电负性增强。同族递变规律：原子半径增大，电离能减小，电负性减弱。

Oxides change from basic (Na₂O, MgO) to amphoteric (Al₂O₃) to acidic (SiO₂, P₄O₁₀, SO₃, Cl₂O₇) across Period 3, reflecting the transition from metallic to non-metallic character.

第三周期氧化物从碱性（Na₂O, MgO）经过两性（Al₂O₃）变为酸性（SiO₂, P₄O₁₀, SO₃, Cl₂O₇），反映出从金属性到非金属性的转变。

4. Chemical Bonding and Structure | 化学键与结构

Ionic bonding occurs between metals and non-metals via electron transfer, forming a giant ionic lattice. The lattice is held by strong electrostatic forces, giving high melting points and electrical conductivity when molten or in solution.

离子键通过电子转移形成于金属与非金属之间，构成巨型离子晶格。晶格由强静电作用力维系，因此熔点高，熔融或溶于水时能导电。

Covalent bonding involves the sharing of electron pairs. The octet rule guides Lewis structures. Bond polarity arises when atoms differ in electronegativity; a molecule can be non-polar overall if the bond dipoles cancel (e.g. CO₂ is linear and non-polar).

共价键通过共用电子对形成。八隅体规则指导路易斯结构的书写。当原子电负性不同时，键具有极性；若键偶极相互抵消，整个分子可能非极性（如 CO₂ 为直线形非极性分子）。

VSEPR theory predicts molecular shapes from the number of electron domains: linear (2 domains, 180°), trigonal planar (3, 120°), tetrahedral (4, 109.5°), trigonal bipyramidal (5, 90° and 120°), octahedral (6, 90°).

VSEPR 理论根据电子域数目预测分子形状：直线形（2 域，180°）、平面三角形（3 域，120°）、四面体形（4 域，109.5°）、三角双锥形（5 域，90° 与 120°）、八面体形（6 域，90°）。

Intermolecular forces: London (dispersion) forces exist in all molecules; dipole–dipole interactions occur between polar molecules; hydrogen bonding (H bonded to N, O, or F) is the strongest, explaining the anomalously high boiling points of H₂O, NH₃ and HF.

分子间作用力：伦敦（色散）力存在于所有分子中；偶极-偶极作用存在于极性分子之间；氢键（H 与 N、O、F 结合时）最强，解释了 H₂O、NH₃ 和 HF 沸点异常高的现象。

5. Energetics / Thermochemistry | 热化学

Enthalpy change (ΔH) is the heat transferred at constant pressure. Exothermic reactions release heat (ΔH < 0); endothermic reactions absorb heat (ΔH > 0). Standard conditions: 100 kPa, 298 K, 1 mol dm⁻³ solutions.

焓变（ΔH）是恒压下传递的热量。放热反应释放热量（ΔH < 0）；吸热反应吸收热量（ΔH > 0）。标准条件：100 kPa、298 K、1 mol dm⁻³ 溶液。

Calorimetry experiments use q = mcΔT to measure heat change. Hess’s Law states that the total enthalpy change for a reaction is independent of the route taken. Bond enthalpies are average values and can be used to estimate ΔH: ΔH ≈ Σ(bonds broken) – Σ(bonds formed).

量热实验使用 q = mcΔT 测量热量变化。赫斯定律表明，反应的总焓变与途径无关。键焓是平均值，可用于估算 ΔH：ΔH ≈ Σ（断键吸热） – Σ（成键放热）。

Standard enthalpy of formation (ΔHᶿ_f) is the enthalpy change when one mole of a compound is formed from its elements under standard conditions. Standard enthalpy of combustion (ΔHᶿ_c) is the enthalpy change when one mole of substance is completely burned in oxygen.

标准生成焓（ΔHᶿ_f）是在标准条件下由元素生成一摩尔化合物时的焓变。标准燃烧焓（ΔHᶿ_c）是一摩尔物质在氧气中完全燃烧时的焓变。

6. Chemical Kinetics | 化学动力学

The rate of reaction is the change in concentration of a reactant or product per unit time. It can be followed by monitoring gas volume, mass change, colour intensity, pH, or conductivity.

反应速率是单位时间内反应物或产物浓度的变化。可通过监测气体体积、质量变化、颜色强度、pH 或电导率来追踪。

Collision theory states that particles must collide with sufficient energy (activation energy, Eₐ) and correct orientation for a reaction to occur. Increasing temperature, concentration, pressure (for gases), or surface area (for solids) increases the frequency and/or energy of collisions.

碰撞理论指出，粒子必须以足够的能量（活化能，Eₐ）和正确的取向碰撞才能发生反应。升高温度、增大浓度、增加气体压力或增大固体表面积都能提高碰撞频率和/或能量。

A catalyst provides an alternative reaction pathway with a lower activation energy, thus speeding up the reaction without being consumed. Enzymes are biological catalysts; heterogeneous catalysts are in a different phase from the reactants.

催化剂提供活化能较低的另一反应途径，从而加快反应而自身不被消耗。酶是生物催化剂；多相催化剂与反应物处于不同相态。

Maxwell–Boltzmann distribution shows the spread of molecular kinetic energies. With a catalyst or at higher temperature, a larger fraction of molecules exceeds Eₐ.

麦克斯韦-玻尔兹曼分布展示了分子动能的分布。使用催化剂或升高温度时，超过活化能的分子比例增大。

7. Equilibrium | 化学平衡

A reversible reaction reaches dynamic equilibrium when the forward and reverse rates are equal and the concentrations of reactants and products remain constant. The equilibrium constant K_c is given by the ratio of product to reactant concentrations, each raised to the power of its stoichiometric coefficient.

可逆反应达到动态平衡时，正逆反应速率相等，反应物与产物的浓度保持不变。平衡常数 K_c 等于产物浓度与反应物浓度之比，各浓度以其化学计量系数为指数。

Le Chatelier’s principle: if a system at equilibrium is subjected to a change in concentration, pressure (volume), or temperature, the equilibrium shifts to partially oppose the change. Catalysts do not affect the position of equilibrium; they only speed up attainment of equilibrium.

勒夏特列原理：若改变平衡体系的浓度、压强（体积）或温度，平衡将向削弱该改变的方向移动。催化剂不影响平衡位置，只加快达到平衡的速度。

For exothermic reactions, increasing temperature shifts equilibrium to the left (favours endothermic reverse reaction), decreasing K_c. For endothermic reactions, increasing temperature increases K_c.

对于放热反应，升高温度平衡向左移动（利于吸热的逆反应），K_c 减小；对于吸热反应，升高温度 K_c 增大。

8. Acids and Bases | 酸与碱

Bronsted–Lowry acid: proton donor. Bronsted–Lowry base: proton acceptor. A conjugate acid–base pair differs by one H⁺. Water is amphiprotic: it can act as both acid and base.

布朗斯特-劳里酸：质子给予体。布朗斯特-劳里碱：质子接受体。共轭酸碱对之间相差一个 H⁺。水是两性的，既能作酸也能作碱。

Strong acids and bases completely dissociate in water (e.g. HCl, NaOH). Weak acids and bases partially dissociate, establishing an equilibrium described by Kₐ or K_b.

强酸和强碱在水中完全电离（如 HCl、NaOH）。弱酸和弱碱部分电离，建立用 Kₐ 或 K_b 描述的平衡。

pH = –log₁₀[H⁺] and pOH = –log₁₀[OH⁻]. At 298 K, pH + pOH = 14. The ionic product of water, K_w = [H⁺][OH⁻] = 1.0 × 10⁻¹⁴ at 298 K. Neutral solutions have [H⁺] = [OH⁻]; at 298 K, pH = 7.

pH = –log₁₀[H⁺]，pOH = –log₁₀[OH⁻]。298 K 时，pH + pOH = 14。水的离子积 K_w = [H⁺][OH⁻] = 1.0 × 10⁻¹⁴（298 K）。中性溶液中 [H⁺] = [OH⁻]；298 K 时 pH = 7。

During an acid–base titration, the pH changes sharply near the equivalence point. A suitable indicator (e.g. phenolphthalein for strong base–strong acid, methyl orange for strong acid–weak base) must have its colour change range within the steep part of the curve. A buffer solution resists changes in pH upon addition of small amounts of acid or base; it consists of a weak acid and its conjugate base, or a weak base and its conjugate acid.

酸碱滴定中，pH 在等当点附近发生突跃。合适的指示剂（如强碱滴强酸用酚酞，强酸滴弱碱用甲基橙）必须使其变色范围落在曲线陡峭部分。缓冲溶液能够抵抗外加少量酸或碱引起的 pH 变化，由弱酸与其共轭碱或弱碱与其共轭酸组成。

9. Redox Processes | 氧化还原过程

Oxidation is the loss of electrons; reduction is the gain of electrons (OIL RIG). A redox reaction involves both processes simultaneously. The oxidising agent is reduced; the reducing agent is oxidised.

氧化是失去电子，还原是得到电子（OIL RIG）。氧化还原反应同时包含这两个过程。氧化剂本身被还原；还原剂本身被氧化。

Oxidation numbers are assigned to atoms to keep track of electron transfer. Key rules: elements have oxidation number 0; oxygen is usually –2 (except in peroxides where it is –1, or with fluorine); hydrogen is +1 with non-metals and –1 with metals; the sum of oxidation numbers equals the overall charge on the species.

氧化数用于追踪电子转移。关键规则：单质氧化数为 0；氧通常为 –2（过氧化物中为 –1，与氟结合时例外）；氢与非金属结合时为 +1，与金属结合时为 –1；氧化数之和等于粒子的总电荷。

A voltaic (galvanic) cell generates electrical energy from a spontaneous redox reaction. The anode is the site of oxidation (negative electrode); the cathode is the site of reduction (positive electrode). The salt bridge completes the circuit and maintains electrical neutrality.

伏打（原）电池通过自发的氧化还原反应产生电能。阳极发生氧化（负极）；阴极发生还原（正极）。盐桥连通电路并保持电中性。

Electrolysis uses an external power source to drive a non-spontaneous redox reaction. In electrolytic cells, the cathode is negative and the anode is positive. Quantitative electrolysis uses Faraday’s laws: Q = It and n(e⁻) = Q / F (F = 96500 C mol⁻¹).

电解利用外部电源驱动非自发的氧化还原反应。在电解池中，阴极为负极，阳极为正极。定量电解运用法拉第定律：Q = It，n(e⁻) = Q / F（F = 96500 C mol⁻¹）。

10. Organic Chemistry | 有机化学

Organic chemistry focuses on carbon compounds. A homologous series is a family of compounds with the same general formula, functional group, and gradual trend in physical properties.

有机化学聚焦于碳的化合物。同系列是一类化合物，具有相同通式、相同官能团以及递变的物理性质。

Homologous Series	Functional Group	Suffix/Prefix
Alkane	C–C (single bonds only)	-ane
Alkene	C=C	-ene
Alcohol	–OH (hydroxyl)	-ol
Carboxylic acid	–COOH	-oic acid

同系列	官能团	词尾/词头
烷烃	C–C（单键）	-ane
烯烃	C=C	-ene
醇	–OH (羟基)	-ol
羧酸	–COOH	-oic acid

Alkanes undergo free-radical substitution with halogens in UV light. Alkenes undergo electrophilic addition (e.g. with H₂, Br₂, HBr, H₂O). Alcohols can be oxidised to aldehydes, ketones, or carboxylic acids; they also undergo esterification with carboxylic acids.

烷烃在紫外光下与卤素发生自由基取代。烯烃发生亲电加成（如与 H₂、Br₂、HBr、H₂O）。醇可被氧化为醛、酮或羧酸；也可与羧酸发生酯化反应。

IUPAC nomenclature: identify the longest carbon chain, number to give the functional group the lowest locant, and name substituents alphabetically. Isomers have the same molecular formula but different arrangements of atoms: structural isomers (different connectivity) and stereoisomers (same connectivity, different spatial arrangement).

IUPAC 命名：找出最长碳链，从离官能团最近的一端开始编号，按字母顺序命名取代基。异构体具有相同分子式但原子排列不同：结构异构（连接方式不同）和立体异构（连接方式相同，空间排列不同）。

11. Measurement and Data Processing | 测量与数据处理

All measurements have uncertainty. The absolute uncertainty is usually half of the smallest scale division of the instrument. Percentage uncertainty = (absolute uncertainty / measured value) × 100%.

所有测量都存在不确定性。绝对不确定度通常为仪器最小刻度的一半。百分不确定度 =（绝对不确定度 / 测量值）× 100%。

Significant figures reflect the precision of a measurement. When adding or subtracting, the result should have the same number of decimal places as the measurement with the fewest decimal places. When multiplying or dividing, the result should have the same number of significant figures as the least precise measurement.

有效数字反映测量的精密度。加减运算时，结果的小数位数应与已知数值中小数位数最少者相同；乘除运算时，结果的有效数字位数应与已知数值中有效数字最少者相同。

Systematic errors are consistent and can be corrected; random errors scatter around the true value and can be reduced by repeating measurements. Outliers should be identified and omitted from averaging. A best-fit line on a graph should pass through the origin if the relationship is direct proportion.

系统误差具有一致性，可以校正；随机误差围绕真值波动，可通过多次重复测量加以减小。应识别异常值并将其从求平均过程中剔除。如果变量关系为正比，最佳拟合线应过原点。

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