📚 588 Quick Revision: Mastering Edexcel IGCSE Science | 588 快速复习：掌握Edexcel IGCSE科学
This comprehensive revision guide covers key topics across Biology, Chemistry and Physics for the Edexcel IGCSE Science syllabus. Use the bilingual explanations, tables and equations to strengthen your understanding and boost your exam confidence. All core concepts are broken down into clear, point-by-point summaries.
这份综合复习指南涵盖了 Edexcel IGCSE 科学大纲中生物、化学和物理的关键主题。通过中英双语解释、表格和方程式来加深理解，提升考试信心。所有核心概念都被分解成清晰、逐点的总结。
1. Cell Structure and Microscopy | 细胞结构与显微镜
All living organisms are made of cells. Animal cells contain a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells also have a cell wall, chloroplasts and a large permanent vacuole.
所有生物都由细胞组成。动物细胞含有细胞核、细胞质、细胞膜、线粒体和核糖体。植物细胞还含有细胞壁、叶绿体和一个大的永久液泡。
The nucleus stores genetic material (DNA) and controls cellular activities. Mitochondria are the site of aerobic respiration, where energy is released. Ribosomes carry out protein synthesis using information from the nucleus.
细胞核储存遗传物质（DNA）并控制细胞活动。线粒体是有氧呼吸的场所，在这里释放能量。核糖体利用来自细胞核的信息进行蛋白质合成。
To view cells, light microscopes and electron microscopes are used. Magnification is calculated using the formula:
要观察细胞，可以使用光学显微镜和电子显微镜。放大倍数的计算公式为：
Magnification = Image size ÷ Actual size
| Feature | Light microscope | Electron microscope |
|---|---|---|
| Radiation | Light | Electrons |
| Max magnification | ~×1500 | ~×2 000 000 |
| Resolution | ~200 nm | ~0.2 nm |
| Colour | Yes (stains needed) | Black and white |
2. Diffusion, Osmosis and Active Transport | 扩散、渗透与主动运输
Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration, down the concentration gradient. It is a passive process that requires no energy.
扩散是粒子从高浓度区域向低浓度区域的净移动，沿浓度梯度进行。这是一个被动过程，不需要能量。
Osmosis is a special type of diffusion – it refers to the movement of water molecules through a partially permeable membrane from a dilute solution to a more concentrated solution.
渗透是一种特殊的扩散——它指的是水分子通过部分透膜从稀溶液向更浓溶液的移动。
Active transport moves substances against the concentration gradient, from low to high concentration. This process requires energy from respiration and carrier proteins in the membrane.
主动运输是物质逆浓度梯度（从低浓度到高浓度）的移动。这一过程需要呼吸作用提供的能量以及膜上的载体蛋白。
Factors affecting the rate of diffusion include temperature, concentration gradient, surface area and diffusion distance (Fick's law).
影响扩散速率的因素包括温度、浓度梯度、表面积和扩散距离（菲克定律）。
Rate of diffusion ∝ (Surface area × Concentration difference) ÷ Diffusion distance
3. States of Matter and Particle Theory | 物质状态与粒子理论
Matter exists in three main states: solid, liquid and gas. The particle model explains the arrangement and movement of particles in each state.
物质以三种主要状态存在：固态、液态和气态。粒子模型可以解释每种状态下粒子的排列和运动情况。
- Solids: particles closely packed in a regular arrangement, vibrating in fixed positions.
- Liquids: particles close together but arranged randomly, able to slide past each other.
- Gases: particles far apart, moving rapidly in all directions.
- 固体：粒子紧密排列，规则分布，在固定位置振动。
- 液体：粒子相互靠近但排列随机，能够相互滑动。
- 气体：粒子相距很远，朝各个方向快速运动。
During changes of state, such as melting or boiling, energy is transferred but the temperature remains constant until the change is complete. Density can be calculated using:
在物态变化过程中，例如熔化或沸腾，能量不断传递，但温度保持恒定直至变化完成。密度可以通过以下公式计算：
ρ = m ÷ V
where ρ is density (kg/m³), m is mass (kg), and V is volume (m³).
其中 ρ 为密度（kg/m³），m 为质量（kg），V 为体积（m³）。
4. Atomic Structure and Isotopes | 原子结构与同位素
Atoms consist of a central nucleus containing protons and neutrons, surrounded by electrons in shells. Protons carry a positive charge, neutrons are neutral, and electrons are negative.
原子由一个含有质子和中子的中心原子核以及核外分层排布的电子组成。质子带正电，中子不带电，电子带负电。
The atomic number (Z) is the number of protons, which defines the element. The mass number (A) is the total number of protons plus neutrons.
原子序数（Z）是质子数，它决定了元素的种类。质量数（A）是质子数与中子数之和。
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. They have identical chemical properties but different physical properties.
同位素是具有相同质子数、不同中子数的同种元素的原子。它们的化学性质相同，但物理性质不同。
Electronic configuration follows the 2,8,8 pattern for the first 20 elements. The number of electrons in the outer shell determines the chemical reactivity of the element.
前 20 号元素的电子排布遵循 2、8、8 的规律。最外层电子数决定了元素的化学活泼性。
5. The Periodic Table | 元素周期表
The modern periodic table arranges elements in order of increasing atomic number. The vertical columns are called groups, and the horizontal rows are called periods.
现代元素周期表按原子序数递增的顺序排列元素。纵列称为族，横排称为周期。
Elements in the same group have the same number of electrons in their outer shell, which gives them similar chemical properties. For example, Group 1 (alkali metals) are highly reactive and form 1+ ions.
同一族元素的最外层电子数相同，因此它们具有相似的化学性质。例如，第 1 族（碱金属）非常活泼，会形成 1+ 离子。
Group 7 (halogens) are diatomic non-metals that react vigorously with metals to form halides. Their reactivity decreases down the group.
第 7 族（卤素）是双原子非金属，能与金属剧烈反应生成卤化物。它们的化学活泼性沿族向下递减。
Group 0 (noble gases) are monatomic and unreactive because they have a full outer electron shell. They are used in lighting and as inert atmospheres.
第 0 族（稀有气体）是单原子的、不活泼的，因为它们具有满的最外层电子层。它们用于照明和提供惰性气氛。
6. Ionic, Covalent and Metallic Bonding | 离子键、共价键与金属键
Ionic bonding occurs between metals and non-metals, where electrons are transferred from the metal to the non-metal. This forms positive cations and negative anions held together by strong electrostatic forces.
离子键形成于金属和非金属之间，电子从金属原子转移到非金属原子。这形成被强大的静电引力结合在一起的阳离子和阴离子。
Covalent bonding happens between non-metal atoms. Atoms share pairs of electrons to achieve a full outer shell. Simple molecular substances like H₂O and CO₂ have low melting points, while giant covalent structures like diamond have very high melting points.
共价键形成于非金属原子之间。原子通过共用电子对来达到满外层结构。像 H₂O 和 CO₂ 这样的简单分子物质具有低熔点，而像金刚石这样的巨型共价结构则具有极高的熔点。
Metallic bonding involves a lattice of positive metal ions surrounded by a 'sea' of delocalised electrons. This structure makes metals good conductors of heat and electricity, and allows them to be malleable and ductile.
金属键涉及正金属离子晶格被离域电子“海洋”包围。这种结构使金属成为良好的热和电的导体，并使其具有延展性和韧性。
Dot and cross diagrams are used to represent the outer shell electrons in bonding. For Edexcel IGCSE, you should be able to draw them for ionic and simple covalent compounds.
点叉图用于表示成键过程中的最外层电子。在 Edexcel IGCSE 中，你应该能够绘制离子化合物和简单共价化合物的点叉图。
7. Chemical Reactions, Equations and Energetics | 化学反应、方程式与能量变化
A chemical reaction always involves the formation of new substances. Physical changes, in contrast, do not produce new chemicals. Signs of a chemical reaction include colour change, gas production, temperature change and precipitate formation.
化学反应总是涉及新物质的生成。相比之下，物理变化不产生新的化学物质。发生化学反应的迹象包括颜色变化、气体生成、温度变化和沉淀生成。
Word equations and balanced symbol equations summarise reactions. The law of conservation of mass states that the total mass of reactants equals the total mass of products.
文字方程式和配平的符号方程式可以概括反应过程。质量守恒定律指出，反应物的总质量等于生成物的总质量。
2Mg + O₂ → 2MgO
Exothermic reactions transfer energy to the surroundings, usually as heat. Endothermic reactions take in energy from the surroundings. Bond breaking requires energy (endothermic), while bond making releases energy (exothermic).
放热反应将能量（通常以热的形式）释放到周围环境中。吸热反应从周围环境中吸收能量。断键需要能量（吸热），而成键则释放能量（放热）。
Catalysts speed up the rate of reaction without being used up. They provide an alternative reaction pathway with a lower activation energy.
催化剂能加快反应速率而自身不被消耗。它们提供了具有较低活化能的替代反应路径。
8. Forces, Motion and Newton's Laws | 力、运动与牛顿定律
Forces can change the speed, direction or shape of an object. Scalar quantities (like speed and distance) have magnitude only, while vector quantities (like velocity and force) have both magnitude and direction.
力可以改变物体的速度、方向或形状。标量（如速率和距离）只具有大小，而矢量（如速度和力）同时具有大小和方向。
Speed (v) is distance travelled per unit time. Acceleration (a) is the rate of change of velocity. The key equations of motion for uniform acceleration are:
速率（v）是单位时间内移动的距离。加速度（a）是速度变化的快慢。匀加速运动的基本公式为：
v = u + at
s = ut + ½at²
v² = u² + 2as
Newton's First Law states that an object remains at rest or in uniform motion unless acted upon by a resultant force. Newton's Second Law describes the relationship:
牛顿第一定律指出，除非受到合外力的作用，否则物体将保持静止或匀速直线运动状态。牛顿第二定律描述了以下关系：
F = m × a
where F is resultant force (N), m is mass (kg) and a is acceleration (m/s²). Newton's Third Law states that every action has an equal and opposite reaction.
其中 F 为合外力（N），m 为质量（kg），a 为加速度（m/s²）。牛顿第三定律指出，每一个作用力都会产生一个大小相等、方向相反的反作用力。
9. Work, Energy and Power | 功、能量与功率
Work is done when a force moves an object through a distance. Energy is transferred during this process. Gravitational potential energy is stored by an object raised above the ground.
当力使物体移动一段距离时，就做了功。在这个过程中，能量发生了转移。被升高到地面以上的物体储存了重力势能。
Work done = Force × distance
GPE = m × g × h
where m is mass (kg), g is gravitational field strength (~9.8 N/kg on Earth), and h is height (m). Kinetic energy depends on mass and speed:
其中 m 为质量（kg），g 为重力场强度（地球约为 9.8 N/kg），h 为高度（m）。动能取决于质量和速率：
K.E. = ½ × m × v²
Power is the rate at which work is done or energy is transferred. It is measured in watts (W).
功率是做功或能量传递的速率。它以瓦特（W）为单位进行度量。
P = Work done ÷ time = Energy transferred ÷ time
ot be created or destroyed. Efficiency = (useful energy output ÷ total energy input) × 100%.
能量守恒定律指出，能量可以被有用地转移、储存或耗散，但不能被创造或消灭。效率 =（有用能量输出 ÷ 总能量输入）× 100%。
10. Thermal Energy Transfer | 热能传递
Heat can be transferred by conduction, convection and radiation. Conduction is the main process in solids where vibrating particles pass on energy; metals are good conductors because of delocalised electrons.
热量可以通过传导、对流和辐射进行传递。传导是固体中的主要过程，振动粒子传递能量；金属因具有离域电子而成为良导体。
Convection occurs in liquids and gases. When a fluid is heated, it expands, becomes less dense and rises, while cooler, denser fluid sinks. This sets up a convection current.
对流发生在液体和气体中。当流体被加热时，它膨胀、密度变小而上升，而较冷、密度较大的流体下沉。这样就形成了对流循环。
All objects emit and absorb infrared radiation. The hotter an object is, the more infrared radiation it emits. Dark, matte surfaces are better absorbers and emitters than light, shiny surfaces.
所有物体都会发射和吸收红外辐射。物体温度越高，发射的红外辐射越多。深色、粗糙的表面比浅色、光滑的表面更善于吸收和发射辐射。
Reducing unwanted energy transfers in a home can be achieved through insulation, double glazing, loft insulation and draught excluders, all of which lower heating costs.
通过使用隔热材料、双层玻璃、阁楼保温层和挡风条，可以减少家庭中不必要的能量传递，从而降低供暖成本。
11. Waves and Sound | 波与声音
Waves transfer energy without transferring matter. Transverse waves (e.g. light, water waves) have oscillations perpendicular to the direction of energy transfer. Longitudinal waves (e.g. sound) have oscillations parallel to the direction of energy transfer.
波传递能量而不传递物质。横波（如光波、水波）的振动方向垂直于能量传递方向。纵波（如声波）的振动方向平行于能量传递方向。
The wave equation links speed (v), frequency (f) and wavelength (λ):
波的速度方程关联了波速（v）、频率（f）和波长（λ）：
v = f × λ
Sound is produced by vibrating objects. The pitch of a sound depends on its frequency; loudness depends on the amplitude of the wave. Humans can typically hear frequencies from 20 Hz to 20 000 Hz.
声音由振动的物体产生。音调的高低取决于声音的频率；响度取决于波的振幅。人类通常能够听到 20 Hz 至 20 000 Hz 的频率。
Sound travels fastest in solids, slower in liquids and slowest in gases because the particles are closer together in solids, allowing vibrations to pass more quickly.
声音在固体中传播最快，在液体中较慢，在气体中最慢，这是因为固体中粒子靠得更近，使得振动能更快地传递。
12. Electromagnetic Spectrum and Applications | 电磁波谱及其应用
ing frequency and decreasing wavelength, the regions are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays.
电磁波谱是一组横波，它们在真空中都以光速（3.0 × 10⁸ m/s）传播。按照频率递增、波长递减的顺序，区域依次为：无线电波、微波、红外线、可见光、紫外线、X 射线和 γ 射线。
| EM wave | Use | Hazard |
|---|---|---|
| Radio | Communication | Very low |
| Microwaves | Heating, satellites | Internal heating |
| Infrared | Remote controls, thermal imaging | Skin burns |
| Visible light | Seeing, photography | Bright light can damage eyes |
| Ultraviolet | Sunbeds, fluorescent lamps | Skin cancer, eye damage |
| X-rays | Medical imaging, security | Cell damage, cancer |
| Gamma rays | Sterilisation, cancer treatment | High cancer risk, mutations |
All EM waves can be reflected, refracted and transmitted. Their dangers increase as the frequency rises because higher-frequency photons carry more energy and can ionise atoms.
所有电磁波都能被反射、折射和透射。随着频率升高，它们的危险性增加，因为频率更高的光子携带更多能量并能电离原子。
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