IGCSE AQA Physics: Nuclear Physics Revision Guide | IGCSE AQA 物理：核物理 考点精讲

📚 IGCSE AQA Physics: Nuclear Physics Revision Guide | IGCSE AQA 物理：核物理 考点精讲

This comprehensive guide covers all the key topics in the IGCSE AQA Physics Nuclear Physics module. We will explore atomic structure, radioactivity, half-life, uses and dangers of radiation, as well as nuclear fission and fusion. The content is tailored to the AQA specification, with clear explanations and bilingual notes to help you master the subject.

本指南全面覆盖 IGCSE AQA 物理核物理模块的所有核心考点。我们将深入探讨原子结构、放射性、半衰期、核辐射的用途与危害，以及核裂变与核聚变。内容紧扣 AQA 考纲，提供清晰的中英双语解析，助你轻松掌握知识点。

1. Atomic Structure and Isotopes | 原子结构与同位素

Atoms consist of a small, dense nucleus containing protons and neutrons, surrounded by electrons in energy levels. The atomic number (Z) is the number of protons, which determines the element. The mass number (A) is the total number of protons and neutrons. Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.

原子由一个致密的原子核和绕核运动的电子组成，原子核包含质子和中子。原子序数（Z）等于质子数，决定了元素种类。质量数（A）为质子数与中子数的总和。同位素是指质子数相同但中子数不同的同一种元素的原子。

We represent a nuclide as ²³⁸₉₂U, where the mass number is written as a superscript and the atomic number as a subscript before the symbol. For example, carbon-12 is ¹²₆C and carbon-14 is ¹⁴₆C. Isotopes have identical chemical properties but different physical properties such as stability.

核素符号通常表示为 ²³⁸₉₂U，其中上标为质量数，下标为原子序数，位于元素符号左侧。例如碳-12 写作 ¹²₆C，碳-14 写作 ¹⁴₆C。同位素化学性质相同，但物理性质（如稳定性）不同。

Number of neutrons = A – Z

2. Radioactive Decay and Nuclear Equations | 放射性衰变与核方程

Radioactive decay is the spontaneous disintegration of an unstable atomic nucleus, resulting in the emission of ionising radiation. The process is random and cannot be influenced by temperature, pressure, or chemical reactions. The nucleus changes into a more stable nucleus of a different element.

放射性衰变是不稳定原子核自发地发生衰变，并放出电离辐射的过程。这一过程是随机的，温度、压强或化学反应无法对其产生影响。衰变后，原子核转变为另一种更稳定的元素的原子核。

In nuclear equations, the total mass number and total atomic number must be conserved. Alpha decay reduces A by 4 and Z by 2. Beta-minus decay increases Z by 1 while A stays the same, as a neutron turns into a proton, emitting an electron and an antineutrino. Gamma decay involves no change in nuclear composition, just the emission of energy.

在核反应方程中，总质量数和总原子序数必须守恒。α衰变使得质量数减少 4，原子序数减少 2。β⁻ 衰变中，一个中子转变为质子，并放出电子和反中微子，因此质量数不变，原子序数增加 1。γ 衰变不改变核的组成，仅释放能量。

Alpha decay: ²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He

Beta decay: ¹⁴₆C → ¹⁴₇N + ⁰₋₁e

3. Properties of Alpha, Beta and Gamma Radiation | α、β、γ 射线的特性

Alpha particles are helium nuclei (⁴₂He), have a charge of +2 and a large mass. They are highly ionising because they can knock electrons out of atoms easily, but they have low penetrating power – stopped by a few centimetres of air or a sheet of paper. In electric and magnetic fields, alpha particles are deflected slightly due to their large mass.

α粒子是氦原子核（⁴₂He），带+2电荷，质量较大。它们具有极强的电离能力，因为容易从原子中击出电子，但穿透能力较弱，几厘米的空气或一张纸就能将其阻挡。在电场和磁场中，α粒子因质量大而只发生轻微偏转。

Beta particles are high-speed electrons (⁰₋₁e). They are less ionising than alpha particles but more penetrating – a few millimetres of aluminium can stop them. In fields, beta particles are deflected more than alpha and in the opposite direction because they are negatively charged.

β粒子是高速电子（

Published by TutorHao | IGCSE Physics Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）