Atoms and Elements: Key Exam Points for IGCSE Edexcel Science | IGCSE Edexcel 科学：原子与元素 考点精讲

📚 Atoms and Elements: Key Exam Points for IGCSE Edexcel Science | IGCSE Edexcel 科学：原子与元素 考点精讲

Atoms are the fundamental building blocks of all matter. Understanding atoms and elements is crucial for mastering the chemistry component of IGCSE Edexcel Science, whether you are taking Double Award or Separate Sciences. This guide breaks down the key concepts, definitions, and exam tips to help you ace this topic.

原子是所有物质的基本构建单元。无论你参加的是双奖科学还是单科科学，理解原子和元素对于掌握IGCSE Edexcel 科学中的化学部分至关重要。本指南分解了关键概念、定义和考试技巧，助你轻松应对这一主题。

1. What is an Atom? | 什么是原子？

An atom is the smallest particle of an element that can take part in a chemical reaction. Atoms are incredibly small – their diameter is about 10⁻¹⁰ m. Each atom consists of a central nucleus containing protons and neutrons, surrounded by electrons arranged in shells. The nucleus is positively charged, holds almost all the mass, while the electron cloud takes up most of the space.

原子是能参与化学反应的元素的最小粒子。原子极其微小，直径约为10⁻¹⁰米。每个原子都有一个包含质子和中子的中心核，核外是分层排布的电子。原子核带正电且几乎集中于全部质量，而电子云则占据了绝大部分体积。

2. Subatomic Particles | 亚原子粒子

There are three main subatomic particles: protons, neutrons, and electrons. Their relative masses and charges are summarised below. Protons and neutrons are found in the nucleus, while electrons move around the nucleus in shells.

共有三种主要的亚原子粒子：质子、中子和电子。它们的相对质量和电荷总结如下。质子和中子位于原子核内，电子则在核外的电子层中运动。

Their properties are given in the table:

其性质如下表所示：

Remember: in a neutral atom, the number of protons equals the number of electrons, so the overall charge is zero.

记住：在中性原子中，质子数等于电子数，因此总电荷为零。

3. Atomic Number and Mass Number | 原子序数与质量数

The atomic number (Z) is the number of protons in the nucleus of an atom. It defines the element – every atom of the same element has the same atomic number. For example, all carbon atoms have 6 protons. The mass number (A) is the total number of protons plus

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