The Periodic Table | 元素周期表

📚 The Periodic Table | 元素周期表

The Periodic Table is one of the most powerful tools in science. It organises all known elements by their atomic number and electron configuration, allowing us to predict physical and chemical properties. In your Edexcel IGCSE Science exam, you will be asked to interpret the table, identify patterns, and link structure to properties.

元素周期表是科学中最强大的工具之一。它按照原子序数和电子排布将所有已知元素组织起来，使我们能够预测其物理和化学性质。在 Edexcel IGCSE 科学考试中，你将被要求解读周期表、识别规律，并将结构与性质联系起来。

1. The Structure of the Periodic Table | 周期表的结构

The modern Periodic Table arranges elements in order of increasing atomic number (number of protons). Each element has a unique atomic symbol, shown with its atomic number above the symbol and its relative atomic mass below it.

现代元素周期表按照原子序数（质子数）递增的顺序排列元素。每种元素都有独特的元素符号，其上方显示原子序数，下方显示相对原子质量。

Atomic number (Z) = number of protons | 原子序数（Z）= 质子数
Mass number (A) = protons + neutrons | 质量数（A）= 质子数 + 中子数
Elements in the same vertical column share similar chemical properties | 同一纵列的元素具有相似的化学性质

Na (Sodium) → Atomic number 11, Mass number 23

钠（Na）→ 原子序数 11，质量数 23

2. Periods and Groups | 周期与族

The table is divided into horizontal rows called periods and vertical columns called groups. The group number tells you how many outer-shell electrons an element has (for Groups 1 and 2, and 5–7).

周期表被划分为横向的周期和纵向的族。族号告诉你该元素具有多少个最外层电子（对于第 1、2 族和第 5–7 族）。

Group 1	1 outer-shell electron	第 1 族：1 个最外层电子
Group 2	2 outer-shell electrons	第 2 族：2 个最外层电子
Group 6	6 outer-shell electrons	第 6 族：6 个最外层电子
Group 7	7 outer-shell electrons	第 7 族：7 个最外层电子

As you move down a group, the number of electron shells increases, so the atomic radius increases and the outer electrons are further from the nucleus.

当一族向下移动时，电子层数增加，因此原子半径增大，最外层电子离原子核更远。

3. Metals and Non-metals | 金属与非金属

A staircase line separates metals (left and bottom) from non-metals (right and top). Metals lose electrons to form positive ions, while non-metals gain electrons to form negative ions.

一条阶梯线将金属（左侧和下方）与非金属（右侧和上方）分开。金属失去电子形成阳离子，而非金属获得电子形成阴离子。

Metals: shiny, conduct heat and electricity, malleable | 金属：有光泽，导热导电，具有延展性
Non-metals: dull, poor conductors (except graphite), brittle | 非金属：暗淡，导电性差（石墨除外），易碎

Most elements are metals. Non-metals are found in the top-right corner, plus hydrogen in Group 1.

大多数元素是金属。非金属位于右上角，外加第 1 族的氢。

4. Group 1: Alkali Metals | 第 1 族：碱金属

Lithium, sodium, and potassium are soft, highly reactive metals. They all have one outer electron, which they lose easily to form a ⁺ ion.

锂、钠和钾是柔软且高反应活性的金属。它们都只有一个最外层电子，容易失去形成 +1 离子。

2Na + 2H₂O → 2NaOH + H₂

Reactivity increases down the group. This is because the outer electron is further from the nucleus, so the attraction is weaker and it is lost more easily.

反应活性向下递增。这是因为最外层电子离核更远，原子核吸引力更弱，更容易失去电子。

5. Group 7: Halogens | 第 7 族：卤素

Fluorine, chlorine, bromine, and iodine are non-metals. They have seven outer electrons and need one more electron to achieve a full outer shell, so they form a ⁻ ion.

氟、氯、溴和碘是非金属。它们有七个最外层电子，需要再获得一个电子才能达到满壳层，因此形成 -1 离子。

Reactivity decreases down the group. A halogen atom becomes larger down the group, so its attraction for an extra electron is weaker.

反应活性向下递减。卤素原子向下变大，对额外电子的吸引力减弱。

Cl₂ + 2KBr → 2KCl + Br₂

A more reactive halogen can displace a less reactive halogen from its salt solution.

更活泼的卤素可以从其盐溶液中置换出较不活泼的卤素。

6. Group 0: Noble Gases | 第 0 族：稀有气体

Helium, neon, argon, krypton, and xenon are unreactive gases. They have full outer shells, so they do not need to lose, gain, or share electrons.

氦、氖、氩、氪和氙是不活泼气体。它们具有全满的最外层电子，因此不需要失去、获得或共享电子。

Their melting and boiling points increase down the group as the atoms get larger.

它们的熔点和沸点随原子变大而向下升高。

Argon (Ar) is used in light bulbs because it is unreactive.

氩（Ar）由于其不活泼性而用于灯泡中。

7. Transition Metals | 过渡金属

The block of elements between Group 2 and Group 3 is known as transition metals. Examples include iron, copper, zinc, and nickel.

位于第 2 族和第 3 族之间的元素区称为过渡金属。例如铁、铜、锌和镍。

They are hard, dense, and shiny | 它们坚硬、致密且有光泽
They have high melting points (except mercury) | 它们具有高熔点（汞除外）
They form coloured compounds | 它们形成有色化合物
They can form ions with different charges, e.g. Fe²⁺ and Fe³⁺ | 它们可以形成不同电荷的离子，如 Fe²⁺ 和 Fe³⁺

Transition metals are often used as catalysts, such as iron in the Haber process.

过渡金属常用作催化剂，例如哈伯工艺中的铁。

8. Predicting Properties from the Table | 利用周期表预测性质

If you know the position of an element, you can predict:

如果你知道元素的位置，你就可以预测：

Group number → number of outer-shell electrons

族号 → 最外层电子数

Period number → number of electron shells

周期号 → 电子层数

For example, calcium is in Group 2 and Period 4, so it has 2 outer-shell electrons and 4 electron shells.

例如，钙位于第 2 族和第 4 周期，因此它有 2 个最外层电子和 4 个电子层。

9. Electron Configuration and the Periodic Table | 电子排布与周期表

Elements in the same group have similar electron configurations in their outer shell. This explains why they react in similar ways.

同一族的元素具有相似的电子构型，这解释了它们为何具有相似的反应方式。

The first shell holds up to 2 electrons, the second and third shells hold up to 8 electrons.

第一壳层最多容纳 2 个电子，第二和第三壳层最多容纳 8 个电子。

Oxygen (atomic number 8): 2, 6

氧（原子序数 8）：2，6

Magnesium (atomic number 12): 2, 8, 2

镁（原子序数 12）：2，8，2

Drawing these configurations helps you understand how ions form and why atoms combine.

画出这些排布有助于你理解离子如何形成以及原子如何结合。

10. Exam Tips for Edexcel IGCSE Science | Edexcel IGCSE 科学考试技巧

In the exam, you should always use the Periodic Table provided unless you are asked to recall a specific element.

在考试中，除非要求回忆特定元素，否则应始终使用提供的周期表。

Make sure you can explain trends in reactivity, atomic radius, and melting point | 确保你能解释反应活性、原子半径和熔点的趋势。
Use correct vocabulary: outer-shell electrons, full shell, reactivity, displacement | 使用准确的词汇：最外层电子、满壳层、反应活性、置换。
Practise writing ion symbols: Na⁺, Ca²⁺, Cl⁻ | 练习书写离子符号：Na⁺、Ca²⁺、Cl⁻。
Remember that Group 0 elements are stable due to full outer shells | 记住第 0 族元素因其最外层全满而稳定。

Always link the electron arrangement to the position in the table. That is the key to scoring full marks.

始终将电子排布与表中的位置联系起来，这是获得满分的关键。

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The Periodic Table | 元素周期表