📚 Year 12 WJEC Chemistry: Rapid Terminology Memory Guide | Year 12 WJEC 化学：术语速记指南
Mastering the essential terminology in Year 12 WJEC Chemistry is the foundation for understanding concepts and achieving top grades. This guide presents a structured approach to memorising key terms and definitions through mnemonic devices, word origins, and contextual examples. Each section introduces a cluster of related terms with memory triggers designed to help you recall them quickly under exam conditions.
掌握 Year 12 WJEC 化学的基础术语是理解概念、获取高分的关键。本指南通过记忆术、词根溯源和情境实例，提供系统的方法来记忆关键术语和定义。每一节介绍一组相关术语，并配有记忆触发器，旨在帮助你在考试中快速回忆。
1. Atomic Structure & Particles | 原子结构与粒子
The atom consists of three subatomic particles: protons (relative mass 1, charge +1), neutrons (mass 1, charge 0), and electrons (mass 1/1836, charge -1). The atomic number (Z) is the number of protons, which defines the element. The mass number (A) is the total number of protons and neutrons. Use the memory cue “A = P + N” to differentiate Z and A. Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons, hence different mass numbers. The relative atomic mass (A₁) is the weighted average mass of an atom relative to 1/12th the mass of a carbon-12 atom, taking isotope abundances into account.
原子由三种亚原子粒子组成：质子（相对质量1，电荷+1）、中子（质量1，电荷0）和电子（质量1/1836，电荷-1）。原子序数(Z)是质子数，决定了元素种类。质量数(A)是质子数与中子数的总和。可用”A = P + N”记忆A与Z的区别。同位素是质子数相同而中子数不同的同种原子，因此质量数不同。相对原子质量(A₁)是原子的加权平均质量，以碳-12原子质量的1/12为标准，考虑了同位素丰度。
To remember the charges, think “proton positive, neutron neutral, electron negative”. For isotope notation, write the element symbol with mass number as superscript and atomic number as subscript, e.g., ¹²₆C. Relative isotopic mass refers to the mass of a single isotope on the same scale; it is essentially the mass number. Mnemonic: “Relative atomic mass is an Average of Isotopes”.
记忆电荷时，记住“质子正、中子中、电子负”。同位素符号写法是将质量数标在左上角，原子序数标在左下角，例如¹²₆C。相对同位素质量是指单一同位素在相同标度上的质量，基本等于质量数。记忆口诀：“相对原子质量是同位素的平均值”。
2. Electron Configuration & Ionisation Energy | 电子排布与电离能
Electrons occupy shells (energy levels) and subshells: s, p, d. An orbital is a region where there is a high probability of finding an electron; each orbital holds a maximum of two electrons with opposite spins. The aufbau principle states that electrons fill the lowest energy orbitals first. Hund’s rule says electrons occupy degenerate orbitals singly before pairing up. The Pauli exclusion principle forbids two electrons in the same orbital from having the same spin. Electron configurations are written using notation like 1s²2s²2p⁶, where the superscript indicates the number of electrons. For example, sodium (Z=11) is 1s²2s²2p⁶3s¹.
电子占据电子层（能级）和亚层：s、p、d。轨道是电子出现概率较高的区域，每个轨道最多容纳两个自旋相反的电子。构造原理指出电子优先填充能量最低的轨道。洪特规则要求电子在兼并轨道中先单独占据再配对。泡利不相容原理禁止同一轨道中的两个电子具有相同的自旋。电子排布写作1s²2s²2p⁶，上标表示电子数。例如钠(Z=11)的排布为1s²2s²2p⁶3s¹。
First ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions. Trend across a period: ionisation energy generally increases due to increasing nuclear charge and similar shielding. Down a group: ionisation energy decreases because outer electrons are farther from the nucleus and more shielded. Visualise ionisation energy as “how tightly the nucleus hugs its outermost electron”; the stronger the hug, the higher the energy.
第一电离能是指从气态原子中移除1摩尔电子形成1摩尔气态1+离子所需的能量。周期规律：同周期从左到右电离能总体升高，因为核电荷增大而屏蔽效应相近。同族从上到下电离能下降，因为外层电子离核更远且屏蔽增强。可以把电离能想象成“原子核对外层电子的拥抱力度”，拥抱越紧，电离能越高。
3. Chemical Bonding Types | 化学键类型
Ionic bonding is the electrostatic attraction between oppositely charged ions formed by electron transfer, typically between a metal and a non-metal. The resulting giant ionic lattice has high melting points and conducts electricity when molten or dissolved because ions become mobile. Covalent bonding involves the sharing of electron pairs between non-metal atoms. Simple molecular substances like water have low melting points, while giant covalent structures such as diamond and silicon dioxide have very high melting points due to networks of strong covalent bonds. Metallic bonding is the attraction between a lattice of positive metal ions and a sea of delocalised electrons, giving metals their conductivity and malleability.
离子键是由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。形成的巨型离子晶格熔点高，在熔融或溶解时因离子可自由移动而导电。共价键涉及非金属原子间共用电子对。简单分子物质如水熔点低，而巨型共价结构如金刚石和二氧化硅由于强共价键网络而具有极高熔点。金属键是正金属离子晶格与离域电子海之间的吸引力，赋予金属导电性和延展性。
A handy memory trick for bonding types: ionic = “give and take”, covalent = “share”, metallic = “sea of electrons”. To decide bond type by electronegativity difference: a large difference (>1.7) usually implies ionic, smaller differences imply polar covalent, and zero difference pure covalent. Dative covalent (co-ordinate) bond forms when both electrons in the shared pair come from the same atom, e.g., the ammonium ion NH₄⁺.
键型记忆技巧：离子键是“给予与接受”，共价键是“分享”，金属键是“电子海”。通过电负性差判断键型：差值大(>1.7)通常为离子键，差值小为极性共价键，零差值为纯共价键。配位键（共价键的一种）是指共用电子对均由同一原子提供，如铵离子NH₄⁺。
4. Molecular Shapes & Polarity | 分子形状与极性
The shape of a molecule is determined by the number of electron pairs (bonding and lone pairs) around the central atom, according to Valence Shell Electron Pair Repulsion (VSEPR) theory. Electron pairs repel to positions of minimum repulsion. Shapes: 2 bonding pairs, 0 lone pairs → linear, 180° (e.g., BeCl₂). 3 bonding, 0 lone → trigonal planar, 120° (e.g., BF₃). 4 bonding, 0 lone → tetrahedral, 109.5° (e.g., CH₄). 3 bonding, 1 lone → pyramidal, approx 107° (e.g., NH₃). 2 bonding, 2 lone → bent, approx 104.5° (e.g., H₂O). Lone pairs repel more strongly than bonding pairs, reducing bond angles.
分子形状由中心原子周围的电子对（成键和孤对）数量决定，遵循价层电子对互斥理论(VSEPR)。电子对相互排斥，趋向于使斥力最小位置。典型形状：2对成键、0孤对→直线形，180°（如BeCl₂）；3成键0孤对→平面三角形，120°（如BF₃）；4成键0孤对→正四面体，109.5°（如CH₄）；3成键1孤对→三角锥形，约107°（如NH₃）；2成键2孤对→V形，约104.5°（如H₂O）。孤对-孤对斥力大于孤对-成键斥力，因而键角被压缩。
Remember the trend by counting “steric number” (number of electron pairs). The phrase “Linear, Trigonal, Tetrahedral” for no lone pairs. Polarity of a molecule depends on both bond polarity and molecular symmetry. A molecule with polar bonds can be non-polar if the shape is symmetrical and dipole moments cancel, e.g., CO₂ is linear and non-polar, while H₂O is bent and polar.
通过“位阻数”（电子对数）来记忆趋势。无孤对电子时，形状依次为直线形、平面三角形、四面体形。分子的极性取决于键的极性和分子的对称性。含有极性键的分子若形状对称且偶极矩抵消，则可能是非极性的，如CO₂为直线非极性分子，而H₂O为V形极性分子。
5. Intermolecular Forces | 分子间作用力
Intermolecular forces are attractive forces between molecules. Van der Waals’ (London) forces exist in all molecules due to temporary fluctuations in electron distribution creating instantaneous dipoles. They increase with the number of electrons and points of contact, therefore boiling points rise with molecular size. Permanent dipole-dipole forces occur between polar molecules. Hydrogen bonding is a special strong dipole-dipole interaction when H is covalently bonded to N, O, or F and has a lone pair on the electronegative atom nearby. This explains the anomalously high boiling points of H₂O, NH₃, and HF.
分子间作用力是分子之间的吸引力。范德华力（伦敦力）存在于所有分子中，由电子分布的瞬时波动产生瞬时偶极引起。它随电子数和接触面积增加而增强，因此沸点随分子大小增大而升高。永久偶极-偶极力存在于极性分子之间。氢键是一种特强的偶极-偶极作用，当H与N、O或F共价键合并附近有电负性原子的孤对电子时形成。这解释了H₂O、NH₃和HF异常高的沸点。
To recall which systems have hydrogen bonding, think “I H-bond with NOF” (N, O, F). The order of strength is: van der Waals’ < permanent dipole-dipole < hydrogen bonding (though very strong van der Waals' can rival small dipole-dipole interactions). For solubility, the rule "like dissolves like" applies: polar and ionic solutes dissolve in polar solvents; non-polar solutes dissolve in non-polar solvents.
记住氢键条件：“我(N)与O、F形成氢键”，即N、O、F。强度顺序：范德华力 < 永久偶极-偶极力 < 氢键（但很强的范德华力可与弱偶极力相当）。溶解性原则：“相似相溶”，极性和离子溶质溶于极性溶剂，非极性溶质溶于非极性溶剂。
6. Energetics & Enthalpy | 能量学与焓变
Enthalpy (H) is a measure of the heat content of a system at constant pressure. Enthalpy change (ΔH) is the heat transferred in a reaction. Exothermic reactions release heat, ΔH negative (products have lower enthalpy than reactants). Endothermic reactions absorb heat, ΔH positive. Standard conditions are 298 K and 100 kPa. Important standard enthalpy changes include ΔH₋° (formation) – the enthalpy change when one mole of a compound is formed from its elements in their standard states, and ΔH₌° (combustion) – the enthalpy change when one mole of a substance is completely burned in oxygen under standard conditions.
焓(H)是恒压下系统热含量的量度。焓变(ΔH)是反应中传递的热量。放热反应释放热量，ΔH为负（生成物焓值低于反应物）。吸热反应吸收热量，ΔH为正。标准条件是298K和100kPa。重要的标准焓变包括标准生成焓ΔH₋°——由标准态元素生成1摩尔化合物时的焓变，以及标准燃烧焓ΔH₌°——1摩尔物质在标准状态下完全燃烧时的焓变。
Hess’s law states that the total enthalpy change for a reaction is independent of the route taken, allowing calculation of unknown ΔH values using known enthalpy changes through an energy cycle. Imagine a mountain climber: the change in altitude between base camp and summit is the same regardless of the path. When using bond enthalpies, remember ΔH ≈ sum of bonds broken (endothermic) – sum of bonds formed (exothermic). This is only an approximation because mean bond enthalpies are used.
盖斯定律指出反应的总焓变与途径无关，可利用已知焓变通过能量循环计算未知ΔH。想象登山者：从大本营到山顶的海拔差与路径无关。利用键焓计算时，ΔH ≈ 断裂键焓总和(吸热) – 形成键焓总和(放热)。这只是近似值，因为使用的是平均键焓。
7. Kinetics & Equilibrium | 动力学与平衡
Reaction rate is the change in concentration of a reactant or product per unit time. Collision theory states that for a reaction to occur, particles must collide with sufficient energy (activation energy, Eₐ) and correct orientation. Factors increasing rate: increasing temperature (more particles with energy ≥ Eₐ), concentration/pressure (more particles per volume), surface area (more exposed particles), and catalysts (provide an alternative pathway with lower Eₐ). The Maxwell-Boltzmann distribution shows the spread of molecular energies; only the tail beyond Eₐ has successful collisions.
反应速率是单位时间内反应物或生成物浓度的变化。碰撞理论认为，反应发生需要粒子以足够的能量（活化能Eₐ）和正确的取向碰撞。提高速率的因素：升高温度（更多粒子能量≥Eₐ）、增大浓度/压强（单位体积粒子增多）、增大表面积（暴露更多粒子）、使用催化剂（提供低Eₐ的替代路径）。麦克斯韦-玻尔兹曼分布显示了分子能量的分布，只有超出Eₐ的部分才能发生有效碰撞。
Dynamic equilibrium occurs in a reversible reaction when the rates of forward and reverse reactions are equal, and concentrations remain constant. Le Chatelier’s principle: if a system at equilibrium is subjected to a change in concentration, pressure, or temperature, the equilibrium position shifts to counteract the change. Mnemonic: “Chatelier counteracts”. The equilibrium constant Kc is expressed as [products] / [reactants] raised to the powers of their stoichiometric coefficients; it only changes with temperature. For an exothermic forward reaction, increasing temperature decreases Kc.
动态平衡是可逆反应中正逆反应速率相等、各物质浓度保持不变的状态。勒夏特列原理：处于平衡的体系若受到浓度、压强或温度的改变，平衡将向减弱这种改变的方向移动。记忆语：“夏特列抵消”。平衡常数Kc表示为生成物浓度幂乘积除以反应物浓度幂乘积，只受温度影响。对于放热正向反应，升温会减小Kc。
8. Redox & Oxidation Numbers | 氧化还原与氧化数
Redox reactions involve the transfer of electrons. Oxidation is the loss of electrons, increase in oxidation number; reduction is the gain of electrons, decrease in oxidation number. Use the mnemonic OIL RIG: Oxidation Is Loss, Reduction Is Gain. An oxidising agent gains electrons and is itself reduced; a reducing agent loses electrons and is itself oxidised. Oxidation numbers are assigned according to rules: elements = 0; monatomic ion equals its charge; oxygen is -2 except in peroxides (-1) and when bonded to fluorine; hydrogen is +1 except in metal hydrides (-1); sum of oxidation numbers in a neutral compound = 0, in a polyatomic ion equals the ion charge.
氧化还原反应涉及电子转移。氧化是失电子、氧化数升高；还原是得电子、氧化数降低。记忆口诀：OIL RIG（氧化是失电子，还原是得电子）。氧化剂得电子自身被还原；还原剂失电子自身被氧化。氧化数规则：单质为0；单原子离子等于其电荷；氧通常为-2（过氧化物中为-1，与氟成键时除外）；氢通常为+1（金属氢化物中为-1）；中性化合物总氧化数为0，多原子离子等于离子电荷。
Example: in MnO₄⁻, oxygen is -2, total for four oxygens is -8; to give an overall charge of -1, Mn must be +7. In redox titrations, like the reaction of Fe²⁺ with MnO₄⁻, the colour change at the endpoint is a useful signal. Balancing half-equations: add electrons to the more positive side to balance charge.
示例：MnO₄⁻中氧为-2，四个氧共-8；为得到总-1电荷，锰为+7。在氧化还原滴定中，如Fe²⁺与MnO₄⁻反应，终点颜色变化是有效信号。半反应配平：在电荷更正的半侧添加电子以平衡电荷。
9. Organic Nomenclature Basics | 有机命名基础
The IUPAC systematic naming identifies the longest continuous carbon chain, the principal functional group, and the positions and names of substituents. Alkanes: general formula CₙH₂ₙ₊₂, suffix -ane. Alkenes: Cₙ
Published by TutorHao | Year 12 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