📚 KS3 CIE Particles Worksheet Mark Scheme | KS3 CIE 粒子单元作业评分标准
This guide works like a marking scheme for a KS3 CIE Particles worksheet. It shows how marks are usually awarded for describing the particle model, explaining diffusion and gas pressure, carrying out density calculations, and using correct scientific vocabulary.
本指南相当于 KS3 CIE 粒子单元作业的评分标准。它展示在描述粒子模型、解释扩散和气体压强、进行密度计算以及使用正确科学用语时，分数通常如何给出。
1. Particle Model Basics | 粒子模型基础
All matter is made of tiny particles. A mark is often given for stating that particles are moving all the time.
所有物质都由微小粒子组成。只要说明粒子一直在运动，通常就能得到 1 分。
In solids, particles vibrate around fixed positions. In liquids and gases, particles can move from place to place.
在固体中，粒子在固定位置附近振动。在液体和气体中，粒子可以从一处移动到另一处。
Higher temperature means particles have more kinetic energy, so they move faster. This idea is needed in many explanation questions.
温度越高意味着粒子具有更多动能，因此运动更快。这个观点在许多解释题中都需要用到。
2. States of Matter: Arrangement and Movement | 物质三态：排列与运动
The three states are solid, liquid and gas. Mark schemes usually award separate marks for arrangement, spacing and movement of particles.
物质三态是固态、液态和气态。评分标准通常对粒子的排列、间距和运动分别给分。
In a solid, particles are closely packed in a regular pattern. They vibrate about fixed positions because strong forces hold them together.
在固体中，粒子紧密排列成规则图案。由于强作用力将它们束缚在一起，粒子只能在固定位置附近振动。
In a liquid, particles are still close together but arranged irregularly. They can slide past each other, so liquids can flow and take the shape of a container.
在液体中，粒子仍然彼此靠近，但排列不规则。它们可以相互滑动，因此液体能够流动并呈现容器的形状。
In a gas, particles are far apart and arranged randomly. They move quickly in all directions, so gases fill the whole container and can be compressed.
在气体中，粒子相距很远且随机排列。它们快速向各个方向运动，因此气体能充满整个容器并容易被压缩。
3. Using Scientific Vocabulary in Answers | 科学用语规范
Marks are often lost because students use everyday words instead of scientific terms. For example, use ‘vibrate’ not ‘shake’ for solid particles.
学生常常因为使用日常用语而不是科学术语而丢分。例如，描述固体粒子时应使用 ‘vibrate’，而不是 ‘shake’。
For liquids, the accepted phrase is ‘slide past each other’ rather than ‘move around a bit’. For gases, say ‘move randomly and quickly’.
描述液体时，被接受的表述是 ‘slide past each other’，而不是 ‘move around a bit’。描述气体时，要说 ‘move randomly and quickly’。
When explaining expansion, do not say the particles expand. Say the spaces between particles increase when the substance is heated.
解释膨胀时，不要说粒子膨胀。要说加热后粒子之间的间距增大。
4. Explaining Diffusion | 解释扩散现象
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration.
扩散是粒子从浓度较高的区域向浓度较低的区域运动。
A complete KS3 answer should mention that particles move randomly, and the overall or net movement is from high to low concentration.
完整的 KS3 答案应提到粒子随机运动，并且整体或净运动是从高浓度到低浓度。
At higher temperatures, diffusion is faster because particles have more kinetic energy and move faster. Mark schemes often award one mark for the speed link.
温度较高时扩散更快，因为粒子具有更多动能，运动更快。评分标准通常给速度联系 1 分。
Example answer: ‘The perfume particles move randomly and spread out from where they are concentrated to the rest of the room.’ This gains marks for random motion and spreading out.
示例答案：’香水粒子随机运动，并从浓度高的地方扩散到房间的其他地方。’ 这个答案因提到随机运动和扩散而得分。
5. Brownian Motion and Evidence for Particles | 布朗运动与粒子证据
Brownian motion is the random, jerky movement of tiny visible particles, such as smoke particles in air, when seen under a microscope.
布朗运动是指在显微镜下观察到的微小可见粒子（如空气中的烟雾粒子）的随机、不规则运动。
This happens because the visible particles are being hit unevenly by much smaller, invisible air particles that are moving randomly.
这是因为可见粒子受到更小、不可见且随机运动的空气粒子的不均匀撞击。
Mark schemes award marks for linking the observed movement to collisions by unseen particles, not for saying the smoke particles move by themselves.
评分标准会将观察到的运动与不可见粒子的碰撞联系起来给分，而不是说烟雾粒子自己会动。
6. Density Calculations | 密度计算
Density is mass per unit volume. The formula used in KS3 worksheets is:
密度是单位体积的质量。KS3 作业中使用的公式是：
density = mass ÷ volume
Mark schemes usually give one mark for writing the formula, one mark for correct substitution, and one mark for the correct answer with the correct unit.
评分标准通常给写出公式 1 分，正确代入 1 分，正确答案及正确单位 1 分。
Example: a block has a mass of 20 g and a volume of 4 cm³. The density is 20 ÷ 4 = 5 g/cm³.
示例：一个物块的质量为 20 g，体积为 4 cm³。密度为 20 ÷ 4 = 5 g/cm³。
If the unit is missing or wrong, one mark may be lost. In KS3, common units are g/cm³ for solids and liquids.
如果单位缺失或错误，可能会扣 1 分。在 KS3 中，固体和液体的常用单位是 g/cm³。
7. Gas Pressure and Particle Collisions | 气体压强与粒子碰撞
Gas pressure is caused by gas particles colliding with the walls of their container. Each collision exerts a small force on the wall.
气体压强是由气体粒子撞击容器壁产生的。每次撞击都会对器壁施加一个微小的力。
If the gas is heated, the particles gain kinetic energy, move faster, and hit the walls more often and with greater force, so pressure increases.
如果气体受热，粒子获得动能，运动更快，更频繁且更有力地撞击器壁，因此压强增大。
If the volume of a container is decreased, particles have less space and hit the walls more often, so pressure increases. Mark schemes want collision frequency or force mentioned.
如果容器体积减小，粒子空间变小，更频繁地撞击器壁，因此压强增大。评分标准要求提到碰撞频率或力的大小。
8. Changes of State and Energy | 状态变化与能量
Melting is solid to liquid; freezing is liquid to solid; boiling and evaporation are liquid to gas; condensation is gas to liquid.
熔化是固态变为液态；凝固是液态变为固态；沸腾和蒸发是液态变为气态；冷凝是气态变为液态。
When a solid melts, particles gain energy and vibrate faster until they can break free from fixed positions and slide past each other.
固体熔化时，粒子获得能量，振动加快，直到能够脱离固定位置并相互滑动。
During a change of state, the temperature stays constant even though energy is still being supplied. This energy is used to overcome forces between particles.
在状态变化过程中，即使仍不断供给能量，温度也保持不变。这些能量用于克服粒子之间的作用力。
Mark schemes often ask for the word ‘energy’ rather than ‘heat’ and for a link to forces between particles.
评分标准通常要求使用 ‘energy’ 而不是 ‘heat’，并且要联系粒子之间的作用力。
9. Common Misconceptions and Marking Notes | 常见错误观念与评分注意
Do not write that particles expand, melt, or change shape. Particles do not change size; the spaces between them change.
不要写粒子会膨胀、熔化或改变形状。粒子本身大小不会改变；改变的是它们之间的间距。
Do not describe air as empty space between particles only. Gas particles are present everywhere in the container and move randomly.
不要把空气说成粒子之间只有空的空间。气体粒子存在于容器的各个地方并随机运动。
Do not say ‘heat makes particles grow’. Say ‘heating gives particles more kinetic energy, so they move faster and spread out’.
不要说 ‘热量使粒子变大’。要说 ‘加热使粒子获得更多动能，因此它们运动更快并扩散开来’。
In longer explanation questions, a mark can be awarded for using the correct scientific terms and another for linking two ideas with ‘because’ or ‘so’.
在较长的解释题中，使用正确的科学术语可得 1 分，用 ‘because’ 或 ‘so’ 将两个观点联系起来可再得 1 分。
10. Sample Mark Scheme Table | 示例评分表
This table shows how marks might be given for common worksheet questions on particles. Use it to check your own answers.
下表展示粒子单元常见作业题如何给分。可以用它来检查自己的答案。
| Question | 问题 | Mark-worthy answer | 得分答案 | Marks | 分数 |
|---|---|---|
| State two properties of a gas. | 写出气体的两个性质。 | Fills its container; can be compressed / particles far apart. | 充满容器；可被压缩 / 粒子相距很远。 | 2 |
| Explain why a smell spreads through a room. | 解释气味如何在房间中扩散。 | Particles move randomly; net movement from high to low concentration. | 粒子随机运动；从高浓度到低浓度的净运动。 | 2 |
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