📚 Year 12 Edexcel Science: A Quick Guide to Key Terminology | Year 12 Edexcel 科学：词汇术语速记指南
Mastering the subject-specific vocabulary is the first decisive step towards excelling in Year 12 Edexcel Science. This guide distils high-frequency terms from physics, chemistry and biology into concise, exam-ready definitions. Each entry is paired with a memory-friendly explanation in both English and Chinese to help you build strong dual-language recall and use terminology with absolute confidence.
掌握学科专业词汇是在 Year 12 Edexcel 科学中脱颖而出的第一步。本指南把物理、化学、生物中的高频术语浓缩成简洁、应考明确的定义。每个词条都配有中英双语解释，帮助建立牢固的双语记忆，让你在使用术语时充满信心。
1. SI Units and Prefixes | 国际单位制与词头
Base quantity – mass: The SI unit of mass is the kilogram (kg). Unlike most base units, kilogram already contains a prefix, but it is treated as the base unit. In calculations, always keep mass in kg unless instructed otherwise.
基本量——质量：质量的国际单位是千克（kg）。与大多数基本单位不同，千克自身就包含词头，但仍被视作基本单位。计算时除非另有说明，质量一律用 kg。
Base quantity – length: Length is measured in metres (m). In practical work you often meet centimetres (cm) and millimetres (mm); convert to metres by dividing by 100 or 1000 before substituting into equations.
基本量——长度：长度的单位是米（m）。实验中常接触厘米（cm）和毫米（mm）；代入公式前先除以100或1000换算成米。
Prefix table (common multipliers):
| Prefix | Symbol | Factor |
| tera | T | 10¹² |
| giga | G | 10⁹ |
| mega | M | 10⁶ |
| kilo | k | 10³ |
| centi | c | 10⁻² |
| milli | m | 10⁻³ |
| micro | µ | 10⁻⁶ |
| nano | n | 10⁻⁹ |
| pico | p | 10⁻¹² |
Comfort with prefixes allows you to express very large and very small quantities succinctly, a skill tested regularly in Edexcel data-response questions.
熟练运用词头让你能够简洁地表达极大和极小量，这是 Edexcel 数据分析题中经常考查的技能。
2. Mechanics and Motion | 力学与运动
Displacement (s): A vector quantity measuring the straight-line distance in a given direction from the starting point. Unit: metre (m). Contrast with distance, which is scalar.
位移（s）：矢量，描述从起点沿某一方向的直线距离，单位为米（m）。区别于标量的路程。
Velocity (v): ty = displacement / time. Vector. Instantaneous velocity is the gradient of a displacement–time graph.
速度（v）：位移的变化率。速度 = 位移 ÷ 时间。矢量。瞬时速度是位移-时间图线的斜率。
Acceleration (a): Vector. A negative acceleration (deceleration) means velocity is decreasing in the direction of motion.
加速度（a）：速度的变化率。a = Δv / Δt。矢量。负加速度（减速）表示沿运动方向的速度在减小。
Resultant force: The single force that represents the vector sum of all forces acting on an object. Free-body diagrams help visualise this.
合力：作用在物体上所有力的矢量和，用一个力来等效。受力分析图有助于直观理解。
Momentum (p): = m v. Conserved in a closed system with no external forces. Impulse = change in momentum.
动量（p）：质量与速度的乘积：p = m v。在无外力的封闭系统中守恒。冲量等于动量的变化量。
Work done (W): = F d cos θ, where θ is the angle between force and displacement. Measured in joules (J).
做功（W）：力使物体移动时所传递的能量。W = F d cos θ，θ 为力与位移的夹角。单位焦耳（J）。
Key equations: v = u + a t | s = u t + ½ a t² | v² = u² + 2 a s
核心公式：v = u + a t | s = u t + ½ a t² | v² = u² + 2 a s
3. Waves and Optics | 波动与光学
Transverse wave: A wave where particle oscillation is perpendicular to the direction of energy transfer. Examples: light, water ripples.
横波：质点振动方向与能量传递方向垂直的波。例如光波、水波涟漪。
Longitudinal wave: A wave where particle oscillation is parallel to energy transfer. Sound waves in air are longitudinal.
纵波：质点振动方向与能量传递方向平行的波。空气中的声波是纵波。
Amplitude (A): Maximum displacement from the equilibrium position. In a transverse wave, it is the height of a crest.
振幅（A）：质点离开平衡位置的最大位移。在横波中为波峰的高度。
Frequency (f): ber of complete oscillations per second. Unit: hertz (Hz). f = 1/T, where T is the period.
频率（f）：每秒完整振动的次数。单位赫兹（Hz）。f = 1/T，T 为周期。
Wave speed: v = f λ. In a vacuum all electromagnetic waves travel at c = 3.00 × 10⁸ m s⁻¹.
波速：v = f λ。真空中所有电磁波的波速 c = 3.00 × 10⁸ m s⁻¹。
Refractive index (n): Ratio of the speed of light in a vacuum to its speed in a medium: n = c / v. Governs Snell's law: n₁ sin θ₁ = n₂ sin θ₂.
折射率（n）：光在真空中的速度与其在介质中速度的比值：n = c / v。满足斯涅尔定律：n₁ sin θ₁ = n₂ sin θ₂。
Total internal reflection: s dense one at an angle of incidence greater than the critical angle C, where sin C = 1/n.
全内反射：当光从光密介质射向光疏介质，且入射角大于临界角 C 时发生，其中 sin C = 1/n。
4. Electricity and Circuits | 电学与电路
Current (I): charge. I = ΔQ/Δt. Unit: ampere (A). Conventional current flows from positive to negative.
电流（I）：电荷的流动速率。I = ΔQ/Δt。单位安培（A）。传统电流方向从正极流向负极。
Potential difference (V): Work done per unit charge. V = W/Q. Also called voltage. Measured in volts (V).
电势差（V）：每单位电荷做功。V = W/Q。也称电压，单位伏特（V）。
Resistance (R): Opposition to current. Ohm's law: V = I R, valid for ohmic conductors at constant temperature. Unit: ohm (Ω).
电阻（R）：对电流的阻碍作用。欧姆定律：V = I R，适用于恒温下的欧姆导体。单位欧姆（Ω）。
Resistivity (ρ): tance to dimensions: R = ρ L / A. Resistivity is temperature-dependent in most conductors.
电阻率（ρ）：联系电阻与尺寸的材料属性：R = ρ L / A。多数导体的电阻率随温度变化。
Electromotive force (ε): Energy supplied to each coulomb of charge by a source. ε = E / Q. Unit: volt (V).
电动势（ε）：电源对每库仑电荷提供的能量。ε = E / Q。单位伏特（V）。
Potential divider: Two resistors in series split the input voltage: V₂ = [R₂/(R₁ + R₂)] × Vin. Used in sensor circuits.
电位分压器：两个串联电阻按比例分配输入电压：V₂ = [R₂/(R₁ + R₂)] × Vin。常用于传感器电路。
5. Atomic Structure and the Periodic Table | 原子结构与元素周期表
Proton: leus. Relative mass ≈ 1, charge = +1. The number of protons defines the atomic number (Z).
质子：原子核中带正电的亚原子粒子。相对质量约 1，电荷 +1。质子数决定原子序数（Z）。
Neutron: particle in the nucleus. Relative mass ≈ 1, charge = 0. Isotopes differ in neutron number.
中子：原子核中的中性粒子。相对质量约 1，电荷为 0。同位素的中子数不同。
Electron: A negatively charged particle orbiting the nucleus. Relative mass ≈ 1/1836, charge = –1. Chemical reactions involve electron transfer or sharing.
电子：绕核运动的带负电粒子。相对质量约 1/1836，电荷 –1。化学反应涉及电子转移或共享。
Relative atomic mass (Aᵣ): Weighted mean mass of an atom compared to 1/12th the mass of carbon-12. Shown on the periodic table.
相对原子质量（Aᵣ）：以碳-12原子质量的 1/12 为基准，元素原子质量的加权平均值。参见元素周期表。
First ionisation energy: aseous atoms: X(g) → X⁺(g) + e⁻. Trend: decreases down a group, increases across a period.
第一电离能：从1摩尔气态原子中移除1摩尔电子所需的能量：X(g) → X⁺(g) + e⁻。规律：同族向下减小，同周期向右增大。
Orbital: A region around the nucleus where there is a high probability of finding an electron. s, p, d, f sub-levels hold a maximum of 2, 6, 10, 14 electrons respectively.
轨道：原子核外电子出现概率较高的区域。s、p、d、f 亚层最多可容纳2、6、10、14个电子。
6. Bonding and Structure | 化学键与结构
Ionic bonding: Electrostatic attraction between oppositely charged ions formed by electron transfer. Typically between a metal and a non-metal. Giant ionic lattice: high melting point, brittle, conducts when molten.
离子键：因电子转移形成的带相反电荷离子之间的静电引力。通常发生在金属与非金属之间。巨型离子晶格：熔点高、脆性，熔融态导电。
Covalent bonding: Electrostatic attraction between a shared pair of electrons and two nuclei. Can be simple molecular (e.g. H₂O) or giant covalent (e.g. diamond, SiO₂).
共价键：共用电子对与两个原子核之间的静电引力。可形成简单分子（如水）或巨型共价结构（如金刚石、SiO₂）。
Electronegativity: Ability of an atom to attract the bonding pair of electrons in a covalent bond. Differences create polar bonds; large differences lead to ionic bonding.
电负性：原子在共价键中吸引电子对的能力。差异形成极性键；差异很大时趋于离子键。
Hydrogen bonding: Strongest type of intermolecular force. Occurs when H is bonded to highly electronegative N, O or F. Responsible for water's high boiling point and ice's lower density.
氢键：最强的分子间作用力。当 H 与电负性很强的 N、O 或 F 成键时产生。使水具有高沸点，冰的密度小于水。
Metallic bonding: Attraction between a lattice of positive metal ions and a 'sea' of delocalised electrons. Gives metals malleability, ductility and electrical conductivity.
金属键：金属正离子晶格与离域电子“海洋”之间的吸引力。赋予金属延展性、可塑性和导电性。
7. Energetics and Thermodynamics | 能量学与热力学
Enthalpy change (ΔH): Heat energy change measured at constant pressure. Unit: kJ mol⁻¹. Standard conditions (ΔH⦵): 298 K, 100 kPa, solutions at 1 mol dm⁻³.
焓变（ΔH）：恒压条件下测量的热量变化。单位 kJ mol⁻¹。标准条件（ΔH⦵）：298 K、100 kPa、溶液浓度 1 mol dm⁻³。
Exothermic reaction: Releases heat to the surroundings; ΔH is negative. Temperature of the surroundings increases. Typical example: combustion.
放热反应：向环境释放热量；ΔH 为负值。环境温度升高。典型例子：燃烧。
Endothermic reaction: Absorbs heat from the surroundings; ΔH is positive. Temperature of the surroundings decreases. Example: thermal decomposition of calcium carbonate.
吸热反应：从环境吸收热量；ΔH 为正值。环境温度降低。例如碳酸钙的热分解。
Hess's law: The total enthalpy change for a reaction is independent of the route taken. Enables calculation of ΔH using known enthalpy changes of formation or combustion.
盖斯定律：反应的总焓变与路径无关。可利用已知生成焓变或燃烧焓变计算 ΔH。
Bond enthalpy (mean): given bond in the gaseous state, averaged over a range of compounds. ΔH ≈ Σ(bonds broken) – Σ(bonds formed).
平均键焓：气态时断裂1摩尔某种化学键所需的能量，取不同化合物中的平均值。ΔH ≈ Σ(断裂键焓) – Σ(生成键焓)。
8. Cell Biology and Organelles | 细胞生物学与细胞器
Eukaryotic cell: Cell with a distinct membrane-bound nucleus and organelles. Examples: animal and plant cells. Typically 10–100 µm in diameter.
真核细胞：具有明确膜包被的细胞核和细胞器的细胞。如动物细胞和植物细胞。直径通常 10–100 µm。
Prokaryotic cell: Simpler cell without a nucleus; genetic material lies in a nucleoid region. Example: bacteria. Much smaller (0.1–5 µm).
原核细胞：无细胞核的较简单细胞；遗传物质位于拟核区。如细菌。体积更小（0.1–5 µm）。
Nucleus: Contains genetic material (DNA) and controls cellular activities. Surrounded by a double membrane (nuclear envelope) with pores.
细胞核：含有遗传物质（DNA）并调控细胞活动。由双层膜（核被膜）包围，上有核孔。
Mitochondrion: Site of aerobic respiration; produces ATP. Has a double membrane; the inner membrane is folded into cristae to increase surface area.
线粒体：有氧呼吸场所，产生 ATP。具双层膜；内膜向内折叠成嵴以增大表面积。
Ribosome: Site of protein synthesis. Free in cytoplasm or bound to rough endoplasmic reticulum. Made of rRNA and proteins; not membrane-bound.
核糖体：蛋白质合成的场所。游离于细胞质中或附着在粗面内质网上。由 rRNA 和蛋白质组成，无膜结构。
Cell wall (plant): Rigid outer layer providing support and shape. Composed mainly of cellulose in plants, peptidoglycan in bacteria.
细胞壁（植物）：提供支撑和形态的刚性外层。植物主要由纤维素组成，细菌为肽聚糖。
9. Biomolecules and Enzymes | 生物分子与酶
Carbohydrate: Organic compound composed of C, H, O (often with H:O ratio 2:1). Divided into monosaccharides (glucose), disaccharides (sucrose) and polysaccharides (starch, glycogen, cellulose).
碳水化合物：由 C、H、O 组成（H:O 比例通常为 2:1）。分为单糖（葡萄糖）、二糖（蔗糖）和多糖（淀粉、糖原、纤维素）。
Lipid (triglyceride): Formed from one glycerol molecule and three fatty acids joined by ester bonds. Hydrophobic; energy storage and insulation.
脂质（甘油三酯）：由1分子甘油与3分子脂肪酸通过酯键结合而成。疏水；用于能量储存和隔热。
Protein: Polymer of amino acids linked by peptide bonds. Primary structure is the sequence; folding into α-helix/β-pleated sheet (secondary), 3D shape (tertiary), and multi-unit association (quaternary).
蛋白质：氨基酸通过肽键连接而成的多聚体。一级结构为序列；折叠成 α-螺旋/β-折叠（二级）、三维形状（三级）和多链组合（四级）。
Enzyme: A biological catalyst, usually a globular protein, that lowers activation energy. Has a specific active site complementary to its substrate. Described by the lock-and-key or induced-fit model.
酶：生物催化剂，通常为球状蛋白，能降低活化能。具有与底物互补的特定活性位点。可用锁钥模型或诱导契合模型描述。
Denaturation: Permanent loss of an enzyme's specific 3D shape, often caused by extreme pH or high temperature, resulting in loss of catalytic function.
变性：酶因极端 pH 或高温等永久性地失去特定三维构象，从而导致催化功能丧失。
10. Genetics and DNA | 遗传学与 DNA
DNA (deoxyribonucleic acid): A double-stranded polymer of nucleotides. Each nucleotide consists of a phosphate group, deoxyribose sugar and a nitrogenous base (A, T, C, G). Strands run antiparallel.
DNA（脱氧核糖核酸）：由核苷酸组成的双链聚合物。每个核苷酸含磷酸基团、脱氧核糖和一个含氮碱基（A、T、C、G）。两条链反向平行。
Complementary base pairing: Adenine pairs with thymine (A–T) via two hydrogen bonds; cytosine pairs with guanine (C≡G) via three hydrogen bonds. Ensures faithful replication.
互补碱基配对：腺嘌呤与胸腺嘧啶（A–T）以两个氢键配对；胞嘧啶与鸟嘌呤（C≡G）以三个氢键配对。保证精确复制。
Gene: A specific sequence of DNA bases that codes for a polypeptide or functional RNA. Located at a fixed position (locus) on a chromosome.
基因：编码多肽或功能性 RNA 的一段特定 DNA 碱基序列。位于染色体的固定位置（基因座）。
Allele: n heterozygotes. Homozygous = two identical alleles; heterozygous = two different alleles.
等位基因：同一基因的不同形式。在杂合子中显性等位基因掩盖隐性等位基因的效应。纯合 = 两个相同等位基因；杂合 = 两个不同等位基因。
Genotype vs phenotype: Genotype is the genetic constitution of an organism; phenotype is the observable characteristic resulting from the genotype and environment.
基因型与表型：基因型是生物体的遗传组成；表型是基因型与环境相互作用下表现出来的可观测特征。
Transcription and translation: Transcription copies a gene's DNA into mRNA in the nucleus. Translation uses mRNA, tRNA and ribosomes to assemble amino acids into a polypeptide chain.
转录与翻译：转录在细胞核内将基因的 DNA 拷贝为 mRNA。翻译利用 mRNA、tRNA 和核糖体将氨基酸组装成多肽链。
Published by TutorHao | Edexcel Year 12 Science Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图