The Reactivity Series of Metals | 金属活动性顺序

📚 The Reactivity Series of Metals | 金属活动性顺序

In IGCSE science, understanding how metals behave with water, acids and other compounds is essential. The reactivity series is a list that ranks metals from most reactive to least reactive, and it helps us predict chemical reactions, choose extraction methods and protect metals from corrosion.

在IGCSE科学中，理解金属与水、酸及其他化合物的反应至关重要。金属活动性顺序是一份按反应活性从高到低排列的金属列表，它能帮助我们预测化学反应、选择金属的冶炼方法并防止金属腐蚀。

1. Why Study Reactivity? | 为什么要学习反应性？

Reactivity tells us how easily a metal loses electrons to form positive ions. A more reactive metal forms ions more easily, so it reacts faster and often releases more energy.

反应性告诉我们金属失去电子形成正离子的难易程度。更活泼的金属更容易形成离子，因此反应更快，释放的能量也往往更多。

By comparing reactivity, we can predict whether a reaction will happen. This is useful in industry, in the laboratory and even in everyday life, such as rusting and battery technology.

通过比较反应活性，我们可以预测反应能否发生。这在工业、实验室乃至日常生活中都非常有用，例如防锈和电池技术。

2. The Reactivity Series | 金属活动性顺序

Metals are arranged from most reactive to least reactive. Carbon and hydrogen are often included in the series for comparison, even though they are non-metals, because they are used in metal extraction and acid reactions.

金属从最活泼到最不活泼排列。碳和氢虽然是非金属，但常被加入活动性顺序中以便比较，因为它们用于金属冶炼和与酸的反应。

K > Na > Ca > Mg > Al > [C] > Zn > Fe > Pb > [H] > Cu > Ag > Au

The elements stand for potassium, sodium, calcium, magnesium, aluminium, carbon, zinc, iron, lead, hydrogen, copper, silver and gold.

这些元素依次为钾、钠、钙、镁、铝、碳、锌、铁、铅、氢、铜、银和金。

3. Explaining the Order | 解释顺序

Reactivity depends on how easily a metal atom loses its outer electrons. A large atom with a small number of outer electrons holds those electrons less tightly, so it is more reactive.

反应活性取决于金属原子失去外层电子的难易程度。较大的原子对外层电子约束较弱，因此更活泼。

This explains why potassium is more reactive than sodium. Potassium has a larger atomic radius and more inner electron shells, so its outer electron is farther from the nucleus and is shielded more effectively.

这解释了为什么钾比钠活泼。钾的原子半径更大，有更多的内层电子壳层，因此它的外层电子离原子核更远，受到的屏蔽也更强。

4. Reactions with Water | 金属与水的反应

Very reactive metals such as potassium, sodium and calcium react with cold water. Potassium and sodium move rapidly on the water surface, fizz and produce hydrogen gas. The solution becomes alkaline because a metal hydroxide forms.

非常活泼的金属如钾、钠、钙能与冷水反应。钾和钠在水面上快速移动、冒气泡并产生氢气。由于生成金属氢氧化物，溶液呈碱性。

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

Magnesium reacts very slowly with cold water but rapidly with steam. Zinc and iron react only with steam. Copper and metals below hydrogen do not react with water.

镁与冷水反应非常缓慢，但与水蒸气反应迅速。锌和铁只与水蒸气反应。铜以及排在氢之后的金属不与水反应。

Zn(s) + H₂O(g) → ZnO(s) + H₂(g)

5. Reactions with Dilute Acids | 金属与稀酸的反应

Metals above hydrogen in the reactivity series react with dilute hydrochloric acid or dilute sulfuric acid to produce a salt and hydrogen gas. The speed of reaction shows the reactivity: magnesium reacts quickly, zinc reacts moderately, iron reacts slowly, and copper does not react.

在金属活动性顺序中位于氢之前的金属能与稀盐酸或稀硫酸反应生成盐和氢气。反应速率反映活动性：镁反应迅速，锌反应适中，铁反应缓慢，铜不反应。

Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂(g)

Fe(s) + 2HCl(aq) → FeCl₂(aq) + H₂(g)

Reactive metals release hydrogen from acids because they donate electrons to hydrogen ions: 2H⁺(aq) + 2e⁻ → H₂(g).

活泼金属能从酸中置换出氢气，因为它们将电子传递给氢离子：2H⁺(aq) + 2e⁻ → H₂(g)。

6. Displacement Reactions | 置换反应

A more reactive metal can displace a less reactive metal from its compound in solution. For example, if zinc is added to copper(II) sulfate solution, zinc dissolves and copper metal deposits.

较活泼的金属能把较不活泼的金属从其化合物溶液中置换出来。例如，将锌加入硫酸铜溶液，锌溶解，同时析出铜。

Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s)

The ionic equation is shorter and shows the key change:

离子方程式更简短，显示关键变化：

Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)

Observations include the blue solution becoming colourless and a brown or red solid forming on the zinc.

观察现象包括蓝色溶液变为无色，以及锌表面生成红棕色固体。

7. The Role of Carbon and Hydrogen | 碳和氢在顺序中的位置

Carbon is placed between aluminium and zinc because it can remove oxygen from the oxides of metals below it. This makes carbon a useful reducing agent in metal extraction.

碳位于铝和锌之间，因为它能从排在它后面的金属氧化物中夺取氧。这使碳在金属冶炼中成为有用的还原剂。

Hydrogen is placed between lead and copper because it acts as a marker for acid reactions: only metals above hydrogen can displace hydrogen from acids. Metals below hydrogen, such as copper and silver, do not react with dilute acids.

氢位于铅和铜之间，因为它是酸反应的标记：只有排在氢之前的金属才能从酸中置换出氢。排在氢之后的金属如铜和银不与稀酸反应。

8. Extracting Metals | 金属的提取

The position of a metal in the reactivity series determines how it is extracted from its ore.

金属在活动性顺序中的位置决定了从矿石中提取它的方法。

Metals above carbon, such as potassium, sodium, calcium, magnesium and aluminium, are extracted by electrolysis of molten compounds.

碳上方的金属如钾、钠、钙、镁和铝，通过熔融化合物的电解法提取。
Metals below carbon but above hydrogen, such as zinc, iron and lead, are extracted by reduction with carbon or carbon monoxide.

位于碳下方但在氢上方的金属如锌、铁和铅，用碳或一氧化碳还原提取。
Copper is often obtained by roasting copper sulfide followed by electrolysis. Silver and gold are so unreactive that they are found uncombined in nature.

铜通常通过焙烧硫化铜然后电解获得。银和金非常不活泼，在自然界中以游离态存在。

9. Corrosion and Sacrificial Protection | 腐蚀与牺牲保护

Reactive metals are often used to protect less reactive metals from corrosion. Since zinc is more reactive than iron, zinc can act as a sacrificial metal: it reacts with oxygen and water instead of the iron, so the iron does not rust.

活泼金属常被用来保护较不活泼金属免受腐蚀。由于锌比铁活泼，锌可作为牺牲金属：它代替铁与氧气和水反应，从而使铁不生锈。

This is why galvanised steel has a zinc coating. Even if the coating is scratched, the zinc still protects the iron because zinc loses electrons more easily than iron.

这就是镀锌钢有锌涂层的原因。即使涂层被刮伤，锌仍然保护铁，因为锌比铁更容易失去电子。

10. The Thermite Reaction | 铝热反应

Aluminium is more reactive than iron. In the thermite reaction, aluminium powder reduces iron(III) oxide to molten iron and releases a large amount of heat.

铝比铁活泼。在铝热反应中，铝粉将氧化铁(III)还原为熔融的铁，并释放大量热量。

Fe₂O₃(s) + 2Al(s) → 2Fe(s) + Al₂O₃(s)

This reaction shows displacement at high temperature and is used in railway welding.

该反应展示了高温下的置换，并用于铁轨焊接。

11. Experimental Comparison | 实验比较

In the school laboratory, you can compare reactivity by adding small pieces of different metals to dilute acid and measuring the rate of bubble formation. A more reactive metal produces gas faster and the temperature rises more.

在学校实验室，可将少量不同金属加入稀酸中，并通过测量气泡产生的速率来比较反应活性。越活泼的金属产生气泡越快，温度升高也越多。

Alternatively, place a metal into a solution of another metal salt and observe whether a displacement reaction occurs. A reaction product can be identified by colour change or by the solid deposit formed.

另一种方法是将一种金属放入另一种金属盐的溶液中，观察是否发生置换反应。可通过颜色变化或生成的固体沉淀来识别产物。

12. Exam Tips and Common Mistakes | 考试技巧与常见错误

Always remember the correct order: K, Na, Ca, Mg, Al, C, Zn, Fe, Pb, H, Cu, Ag, Au.

务必记牢正确顺序：K, Na, Ca, Mg, Al, C, Zn, Fe, Pb, H, Cu, Ag, Au。
Use state symbols in equations: (s), (l), (g), (aq).

在方程式中使用状态符号：(s)、(l)、(g)、(aq)。
Do not confuse reactions with water and reactions with acid. Sodium reacts violently with both, while copper reacts with neither cold water nor dilute acid.

不要混淆与水反应和与酸反应。钠与两者都反应剧烈，而铜既不与冷水反应，也不与稀酸反应。
In displacement reactions, the more reactive metal loses electrons and the less reactive metal gains electrons, forming a new metal and a new salt.

在置换反应中，较活泼金属失去电子，较不活泼金属得到电子，生成新的金属和新的盐。

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The Reactivity Series of Metals | 金属活动性顺序