📚 AQA AS Chemistry Unit 1 January 2021 Mark Scheme: Key Concepts and Exam Tips | AQA AS 化学第一单元 2021年1月评分方案：核心考点与应试技巧
The January 2021 AQA AS Chemistry Unit 1 mark scheme rewards precise scientific language, correct units, and clear logical steps in calculations. This article breaks down the most important areas assessed in that paper and shows you how to use mark scheme wording to maximise your score.
2021年1月AQA AS化学第一单元评分方案高度重视科学表述的准确性、单位的正确使用以及计算过程中清晰合理的步骤。本文将拆解该试卷考查的核心内容，并教你如何利用评分方案中的常用表述来争取更高分数。
1. Overview and Paper Structure | 试卷结构与评分概览
The AS Unit 1 paper covers physical and inorganic chemistry including atomic structure, amount of substance, bonding, energetics, kinetics, equilibria, redox, and selected inorganic reactions. The mark scheme often gives separate marks for definitions, explanations of trends, and multi-step calculations.
AS第一单元试卷涵盖物理化学与无机化学，包括原子结构、物质的量、化学键、能量学、动力学、平衡、氧化还原以及部分无机反应。评分方案通常对定义、趋势解释和多步计算分别给分。
Questions are usually arranged with short one-mark answers first, followed by structured calculations and longer explanation questions. This means you should manage your time carefully and not spend too long on a single calculation at the start of the paper.
试题通常先出现一分的简短回答，然后是结构化计算和较长的解释题。这意味着你需要合理分配时间，不要在试卷开头的某一道计算题上花费过长时间。
2. Atomic Structure and Ionisation Energies | 原子结构与电离能
Ionisation energy questions require you to state that energy is needed to remove one mole of electrons from one mole of gaseous atoms. For trends, you must refer to shielding, nuclear charge, and distance of the outer electron from the nucleus.
电离能题目要求你说明从一摩尔气态原子中移除一摩尔电子需要能量。解释趋势时，必须提及屏蔽效应、核电荷以及外层电子离核的距离。
X(g) → X⁺(g) + e⁻
The above equation represents the first ionisation energy of an element X. The mark scheme expects this equation or a clear written definition, usually with state symbols included.
上述方程式表示元素X的第一电离能。评分方案要求写出该方程式或清晰的定义，通常需要包含状态符号。
A common mark scheme phrase is "electron removed from a higher energy level" or "more shielding so weaker attraction". Avoid vague statements such as "the atom gets bigger" without linking to attraction.
评分方案中常见表述是“电子从更高能级移除”或“屏蔽更多导致吸引力减弱”。避免使用“原子变大”等不联系吸引力的模糊说法。
3. Amount of Substance and Mole Calculations | 物质的量与摩尔计算
nRT. You must convert volumes to m³, pressure to Pa, and temperature to K before substituting values.
评分方案要求正确使用 n = m / M 和理想气体方程 pV = nRT。代入数值前，必须将体积换算成立方米、压力换算成帕斯卡、温度换算成开尔文。
pV = nRT
In the ideal gas equation, p is pressure in pascals, V is volume in cubic metres, n is the amount in moles, R is the gas constant, and T is temperature in kelvin. Always show the conversion steps clearly in your working.
在理想气体方程中，p表示压力（帕斯卡），V表示体积（立方米），n表示物质的量（摩尔），R是气体常数，T是温度（开尔文）。解题时应清晰写出所有换算步骤。
Many candidates lose marks for incorrect significant figures or forgetting units such as mol dm⁻³. The mark scheme often states "allow consequential marking" for an arithmetic slip, so show full working.
许多考生因有效数字错误或遗漏 mol dm⁻³ 等单位而失分。评分方案常写明“允许连续性给分”（consequential marking），因此要展现完整计算过程。
4. Bonding and Structure | 化学键与结构
For bonding questions, you must use precise terms: "electrostatic attraction between positive ions and delocalised electrons" for metallic bonding, and "electrostatic attraction between oppositely charged ions" for ionic bonding.
在化学键题目中，必须使用精准术语：金属键是“正离子与离域电子之间的静电吸引力”，离子键是“带相反电荷离子之间的静电吸引力”。
When comparing melting points, link the answer to the strength of the attractive forces and the energy needed to overcome them. Mention charge density for ionic compounds and number of delocalised electrons for metals.
比较熔点时，要将答案与吸引力强度以及克服这些力所需能量联系起来。离子化合物要提及电荷密度，金属要提及离域电子数目。
For covalent substances, distinguish between the strong covalent bonds within molecules and the weak intermolecular forces between molecules. This distinction is frequently required in mark schemes when explaining low melting points of simple molecular substances.
对于共价物质，要区分分子内部强的共价键和分子之间弱的分子间作用力。在解释简单分子物质低熔点时，评分方案经常要求明确这一区别。
5. Shapes of Molecules and Intermolecular Forces | 分子形状与分子间作用力
VSEPR marks require both the name of the shape and the bond angle. You must state that lone pairs repel more strongly than bonding pairs, reducing the bond angle by about 2.5° per lone pair.
VSEPR相关分数既要求写出分子形状名称，也要求写出键角。必须说明孤对电子的排斥力比成键电子对更强，每对孤对电子约使键角减小2.5°。
For intermolecular forces, distinguish between London forces, permanent dipole-dipole forces, and hydrogen bonding. The mark scheme often asks for a diagram showing hydrogen bonding with labelled partial charges.
对于分子间作用力，要区分伦敦力、永久偶极-偶极力和氢键。评分方案常要求画出氢键示意图，并标出部分电荷。
When explaining trends in boiling points down a group of hydrides, use the phrase "increasing strength of London forces with increasing relative molecular mass" where appropriate. For water and hydrogen fluoride, refer to hydrogen bonding.
在解释同族氢化物沸点变化趋势时，适当使用“相对分子质量增大导致伦敦力增强”的表述。对于水和氟化氢，则要提及氢键。
6. Energetics and Hess's Law | 能量学与赫斯定律
Hess's law questions require a clear cycle or an algebraic expression. State that enthalpy change is independent of the route taken. Always include state symbols because enthalpy changes depend on state.
赫斯定律题目要求清晰的循环图或代数表达式。要说明焓变与途径无关。始终写出状态符号，因为焓变取决于物质状态。
ΔH = Σ(bonds broken) − Σ(bonds formed)
In bond enthalpy calculations, remember that bond breaking is endothermic and bond making is exothermic. Many mark schemes award one mark for the correct sign and one for the numerical value.
在键焓计算中，记住断键吸热、成键放热。许多评分方案对正确符号给一分，对正确数值给一分。
e mass m is usually the mass of the solution, not the solid. Then convert the heat change to an enthalpy change per mole.
使用量热法数据时，用 q = mcΔT，并记住质量 m 通常是溶液的质量，而不是固体的质量。然后将热量变化换算为每摩尔的焓变。
7. Kinetics and the Maxwell-Boltzmann Distribution | 动力学与麦克斯韦-玻尔兹曼分布
For rate questions, the mark scheme requires reference to collision frequency and the fraction of particles with energy greater than or equal to the activation energy. Use phrases like "more particles have sufficient energy to react".
在速率题目中，评分方案要求提及碰撞频率以及能量大于或等于活化能的粒子比例。使用“更多粒子具有足够能量发生反应”等表述。
When explaining the effect of a catalyst, state that it provides an alternative reaction pathway with lower activation energy, but does not change the position of equilibrium or the yield.
解释催化剂作用时，要说明它提供了活化能较低的替代反应路径，但不改变平衡位置或产率。
If a question asks you to sketch a Maxwell-Boltzmann distribution, label the axes clearly: number of molecules on the y-axis and energy on the x-axis. Show activation energy and the area beyond it.
如果题目要求绘制麦克斯韦-玻尔兹曼分布曲线，需清晰标注坐标轴：纵轴为分子数目，横轴为能量。标出活化能以及超过活化能的区域。
8. Chemical Equilibria and Kc | 化学平衡与平衡常数 Kc
Kc expressions must use equilibrium concentrations in mol dm⁻
Published by TutorHao | AS 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