The Reactivity Series | 金属活动性顺序

📚 The Reactivity Series | 金属活动性顺序

The reactivity series is one of the most important frameworks in IGCSE chemistry. It links laboratory observations to industrial extraction, and it appears again and again in exam questions about metals.

金属活动性顺序是 IGCSE 化学中最重要的框架之一。它把实验室现象与工业冶炼联系起来，也是考试中有关金属的题目反复考查的核心内容。

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1. What is the Reactivity Series? | 什么是金属活动性顺序？

The reactivity series is a list of metals arranged in order of how quickly and vigorously they react. A more reactive metal will react faster and release more energy when it reacts with water, acid or oxygen.

金属活动性顺序是一份按金属反应速度和剧烈程度排列的清单。活动性越强的金属，在与水、酸或氧气反应时速度越快，释放的能量也越多。

You are expected to know the order by heart for Edexcel IGCSE Science, and to use it to predict reactions, explain observations and choose suitable extraction methods.

在 Edexcel IGCSE Science 中，你应当熟记这个顺序，并会用它预测反应、解释现象以及选择合适的金属冶炼方法。

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2. The Order of Metals | 金属的顺序

The standard reactivity series used by Edexcel includes the following metals and hydrogen. Carbon is also included because it is used to extract metals from their ores.

Edexcel 考试使用的标准金属活动性顺序包含下列金属和氢。其中还包含碳，因为碳常用于从矿石中冶炼金属。

Reactivity (most → least)	Element / Symbol
Potassium | 钾	K
Sodium | 钠	Na
Calcium | 钙	Ca
Magnesium | 镁	Mg
Aluminium | 铝	Al
Carbon | 碳	C
Zinc | 锌	Zn
Iron | 铁	Fe
Lead | 铅	Pb
Hydrogen | 氢	H
Copper | 铜	Cu
Silver | 银	Ag
Gold | 金	Au

A common way to remember this is: “Please Stop Call My Al’s Cat Zulu, I Love Hunting Cheap Silver Gold”. You can create your own phrase as long as the order is correct.

一个常见的记忆口诀是：“Please Stop Call My Al’s Cat Zulu, I Love Hunting Cheap Silver Gold”。你也可以自编句子，只要顺序正确即可。

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3. Reactions with Water | 金属与水的反应

Very reactive metals such as potassium, sodium and calcium react with cold water to give hydrogen gas and a metal hydroxide solution. The reaction becomes less violent as you go down the list.

钾、钠、钙等活泼金属能与冷水反应，生成氢气和金属氢氧化物溶液。随着活动性下降，反应剧烈程度逐渐减弱。

Potassium and sodium move rapidly on water. Sodium melts and fizzes; potassium may catch fire with a lilac flame.

钾和钠在水中迅速移动。钠会熔化成小球并嘶嘶作响；钾可能会燃烧并产生淡紫色火焰。

Calcium sinks and produces a steady stream of bubbles. Magnesium reacts very slowly with cold water but quickly with steam.

钙会下沉并持续冒出气泡。镁与冷水反应很慢，但与水蒸气反应很快。

Equations to remember:

2Na + 2H₂O → 2NaOH + H₂

Ca + 2H₂O → Ca(OH)₂ + H₂

Mg + H₂O(g) → MgO + H₂

The first two show that alkali is produced; the third uses steam, forming an oxide instead of a hydroxide.

前两个反应说明有碱生成；第三个反应使用水蒸气，生成氧化物而不是氢氧化物。

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4. Reactions with Acids | 金属与酸的反应

Metals above hydrogen in the reactivity series react with dilute hydrochloric acid or dilute sulfuric acid to form a salt and hydrogen gas.

位于氢上方的金属能与稀盐酸或稀硫酸反应，生成盐和氢气。

Metals below hydrogen, such as copper, silver and gold, do not react with dilute acid under normal conditions.

氢下方的金属，如铜、银、金，在正常条件下不与稀酸反应。

The fizzing shows that hydrogen gas is produced. A burning splint gives a squeaky pop with hydrogen.

气体产生时会有气泡冒出。将点燃的木条伸入氢气中会发出“噗”的爆鸣声。

Examples of word equations:

Magnesium + hydrochloric acid → magnesium chloride + hydrogen

Zinc + sulfuric acid → zinc sulfate + hydrogen

Symbol equations for these are:

Mg + 2HCl → MgCl₂ + H₂

Zn + H₂SO₄ → ZnSO₄ + H₂

Reaction rate increases as the metal becomes more reactive. Magnesium reacts much faster than zinc or iron.

反应速率随金属活动性增强而加快。镁的反应速率远大于锌或铁。

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5. Displacement Reactions | 置换反应

A more reactive metal can displace a less reactive metal from a solution of its salt. This is called a displacement reaction.

活动性更强的金属可以把活动性更弱的金属从其盐溶液中置换出来，这类反应称为置换反应。

For example, iron is more reactive than copper, so iron placed in copper(II) sulfate solution displaces copper:

例如，铁的活动性强于铜，因此将铁放入硫酸铜溶液中可以置换出铜：

Fe + CuSO₄ → FeSO₄ + Cu

The blue copper(II) sulfate solution becomes pale green because iron(II) sulfate forms. A brown solid copper layer is deposited on the iron.

蓝色的硫酸铜溶液会变为浅绿色，因为生成了硫酸亚铁；铁表面会沉积一层棕红色的铜。

Another useful example is when copper is placed in silver nitrate solution:

另一个常见例子是将铜放入硝酸银溶液中：

Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag

The silver crystals grow on the copper wire, and the solution slowly turns blue.

银晶体在铜丝上析出，溶液逐渐变成蓝色。

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6. Oxidation and Reduction in Metal Extraction | 金属冶炼中的氧化与还原

Metals in the reactivity series often exist in ores as positive ions, combined with oxygen or other non-metals such as sulfur.

金属活动性顺序中的金属在矿石中通常以正离子形式存在，与氧或硫等非金属结合。

Extracting a metal from its oxide means removing oxygen from the oxide. Removing oxygen is called reduction; gaining oxygen is called oxidation.

从金属氧化物中冶炼金属，本质是除去氧化物中的氧。失氧称为还原，得氧称为氧化。

When a metal oxide reacts with carbon, carbon removes the oxygen from the metal oxide. The metal is reduced, and carbon is oxidised.

当金属氧化物与碳反应时，碳夺取氧化物中的氧。金属被还原，碳被氧化。

Take zinc oxide as an example:

ZnO + C → Zn + CO

Zinc is reduced from Zn²⁺ to Zn atoms, while carbon is oxidised from C to CO.

锌从 Zn²⁺ 被还原为 Zn 原子，碳则被氧化为 CO。

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7. Extracting Metals with Carbon | 用碳冶炼金属

Metals below carbon in the reactivity series can be extracted by heating their oxides with carbon. This works because carbon is more reactive and can remove oxygen from the metal oxide.

位于碳下方的金属，可以通过将它们的氧化物与碳共热来冶炼。这是因为碳的活动性更强，能够夺取金属氧化物中的氧。

This method is used for zinc, iron, lead and copper in the industrial extraction process.

工业上冶炼锌、铁、铅和铜都采用这种方法。

Example for iron from iron(III) oxide:

2Fe₂O₃ + 3C → 4Fe + 3CO₂

For lead(II) oxide:

2PbO + C → 2Pb + CO₂

The metal oxide is reduced to the metal, and carbon is oxidised to carbon monoxide or carbon dioxide.

金属氧化物被还原为金属单质，碳被氧化为一氧化碳或二氧化碳。

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8. Extracting Metals by Electrolysis | 用电解冶炼金属

Metals above carbon, such as potassium, sodium, calcium, magnesium and aluminium, cannot be extracted by carbon reduction because carbon is less reactive than them.

位于碳上方的金属，如钾、钠、钙、镁和铝，不能用碳还原法冶炼，因为碳的活动性不如它们。

These metals must be extracted by electrolysis of their molten (melted) compounds.

这些金属必须通过电解熔融化合物来提取。

For aluminium, purified aluminium oxide is dissolved in molten cryolite to lower the melting point. This reduces the energy cost.

对于铝，需要将纯净的氧化铝溶解在熔融冰晶石中，以降低熔点，从而减少能源消耗。

The reactions at the electrodes can be summarised as:

Al³⁺ + 3e⁻ → Al (at the cathode)

2O²⁻ → O₂ + 4e⁻ (at the anode)

Overall for molten alumina:

2Al₂O₃ → 4Al + 3O₂

Potassium and sodium are extracted by electrolysing their molten chlorides or hydroxides.

钾和钠则通过电解熔融氯化物或氢氧化物来制取。

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9. Practical Applications | 实际应用

The reactivity series helps us choose the correct method of extraction, predict corrosion, and understand why some reactive metals never exist free in nature.

金属活动性顺序帮助我们选择正确的冶炼方法、预测腐蚀，并理解为什么某些活泼金属在自然界中不以单质形式存在。

Gold and silver are so unreactive that they can be found naturally as elements. In contrast, potassium and sodium always occur in compounds.

金和银性质很不活泼，可以以单质形式存在于自然界中。而钾、钠总是以化合物形式存在。

A more reactive metal can protect a less reactive metal from corrosion. Zinc is used to coat iron in galvanising; this is an example of sacrificial protection.

更活泼的金属可以保护较不活泼的金属免受腐蚀。例如用锌镀在铁表面来防锈，这就是牺牲阳极保护法。

In the lab, you might be asked to place a metal into a salt solution and record observations. Use the reactivity series to predict whether a displacement reaction will occur.

在实验室中，你可能会被要求将一种金属放入盐溶液中并记录现象。使用金属活动性顺序可判断置换反应是否会发生。

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10. Solved Example and Common Mistakes | 例题与常见错误

Example: A piece of copper is placed in iron(II) sulfate solution. Predict whether a reaction occurs and explain your answer.

例题：将一小片铜放入硫酸亚铁溶液中。请判断反应是否会发生并解释原因。

Answer: No reaction occurs. Copper is less reactive than iron, so copper cannot displace iron from iron(II) sulfate. No colour change or solid change is seen.

答案：不发生反应。铜的活动性弱于铁，因此铜不能将铁从硫酸亚铁溶液中置换出来。没有颜色变化或固体变化。

Common mistakes include thinking that all metals react with acid; remembering that only metals above hydrogen react with acid. Also, do not confuse the position of carbon with that of hydrogen.

常见错误包括认为所有金属都能与酸反应；应记住只有氢上方的金属才能与酸反应。另外，不要混淆碳和氢在顺序中的位置。

Another common error is writing displacement equations with incorrect charges. Always check that the formula of the salt is correct before balancing.

另一个常见错误是写置换方程式时离子电荷不正确。在配平之前，务必检查盐的化学式是否写对。

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