📚 The Reactivity Series and Extraction of Metals | 活泼性顺序与金属提取
The reactivity series is a list of metals arranged in order of their tendency to lose electrons and form positive ions. Understanding this series is essential for predicting how metals react with different substances and how they are extracted from their ores. In IGCSE Edexcel Science, you will learn how to construct the series based on experimental observations and use it to explain key industrial processes such as the extraction of iron and aluminium.
活泼性顺序是根据金属失去电子形成阳离子的倾向排列的顺序表。理解这一顺序对于预测金属与不同物质的反应以及如何从矿石中提取金属至关重要。在IGCSE Edexcel 科学课程中，你将学习如何根据实验现象构建该顺序，并运用它解释炼铁和炼铝等重要工业过程。
1. Introduction to the Reactivity Series | 活泼性顺序简介
The reactivity of a metal depends on how easily its atoms lose electrons to form positive ions. Metals that lose electrons more readily are described as more reactive. This tendency can be observed through the vigour of their reactions with oxygen, water and dilute acids.
金属的活泼性取决于其原子失去电子形成阳离子的难易程度。更容易失去电子的金属被描述为更活泼。这种倾向可以通过它们与氧气、水和稀酸反应的剧烈程度观察到。
In all reactions, reactive metals act as reducing agents because they donate electrons to other species. The reactivity series allows chemists to compare the relative reactivity of metals and make predictions about displacement reactions and extraction methods.
在所有反应中，活泼金属作为还原剂，因为它们向其他物质提供电子。活泼性顺序使化学家能够比较金属的相对活泼性，并预测置换反应和提取方法。
Metal → Metalⁿ⁺ + ne⁻
金属 → 金属ⁿ⁺ + ne⁻
2. Reaction of Metals with Oxygen | 金属与氧气的反应
Most metals react with oxygen to form metal oxides. The reactivity of the metal determines how vigorously this reaction occurs. Potassium and sodium burn vigorously, while gold and silver do not react at all.
大多数金属与氧气反应生成金属氧化物。金属的活泼性决定了该反应的剧烈程度。钾和钠剧烈燃烧，而金和银则完全不反应。
Magnesium burns with a brilliant white flame to form a white powder of magnesium oxide. Iron glows brightly and forms a black iron oxide when heated in oxygen. Copper does not burn but gradually turns black as a layer of copper(II) oxide forms.
镁燃烧时发出耀眼的白光，生成白色氧化镁粉末。铁在氧气中加热时发出明亮的光，形成黑色的四氧化三铁。铜不会燃烧，但表面逐渐变黑，形成一层氧化铜。
gen → metal oxide. The balanced chemical equations for some key reactions are shown below.
这些反应的一般文字方程式为：金属 + 氧气 → 金属氧化物。一些关键反应的配平化学方程式如下所示。
2Mg + O₂ → 2MgO
3Fe + 2O₂ → Fe₃O₄
2Cu + O₂ → 2CuO
4K + O₂ → 2K₂O
3. Reaction of Metals with Water | 金属与水的反应
The reaction of metals with water provides a clear method to establish a reactivity order. Very reactive metals such as potassium, sodium and calcium react vigorously with cold water, producing a metal hydroxide and hydrogen gas.
金属与水的反应提供了建立活泼性顺序的明确方法。钾、钠和钙等非常活泼的金属与冷水剧烈反应，生成金属氢氧化物和氢气。
Potassium reacts so violently that the hydrogen produced catches fire immediately. Sodium melts into a silvery ball and darts around the water surface. Calcium reacts steadily, producing a cloudy suspension of calcium hydroxide.
钾的反应非常剧烈，生成的氢气会立即着火。钠熔化成闪亮的银色小球在水面四处游动。钙平稳反应，生成悬浊的氢氧化钙。
Magnesium reacts very slowly with cold water but reacts vigorously with steam to form magnesium oxide and hydrogen. Aluminium, zinc and iron only react with steam at high temperatures, forming the metal oxide and hydrogen. Copper, silver and gold show no reaction with water or steam.
镁与冷水反应非常缓慢，但与水蒸气剧烈反应生成氧化镁和氢气。铝、锌和铁只有在高温下才能与水蒸气反应，生成金属氧化物和氢气。铜、银和金与水或水蒸气均无反应。
2Na + 2H₂O → 2NaOH + H₂
Ca + 2H₂O → Ca(OH)₂ + H₂
Mg + H₂O (steam) → MgO + H₂
4. Reaction of Metals with Dilute Acids | 金属与稀酸的反应
Metals react with dilute hydrochloric acid or dilute sulfuric acid to produce a salt and hydrogen gas. The rate of bubbling of hydrogen gas indicates the reactivity of the metal: the more reactive the metal, the more vigorous the effervescence.
金属与稀盐酸或稀硫酸反应生成盐和氢气。氢气气泡产生的速率表明了金属的活泼性：金属越活泼，冒泡就越剧烈。
Potassium and sodium react explosively with dilute acids, making such reactions far too dangerous for the school laboratory. Calcium and magnesium react very quickly, producing a rapid stream of bubbles. Aluminium reacts moderately fast once the thin layer of aluminium oxide has been removed by the acid.
钾和钠与稀酸的反应会爆炸，对于学校实验室来说过于危险。钙和镁反应非常快，产生快速的气泡流。铝一旦被酸去除表面的氧化铝薄层，反应速度适中。
Zinc reacts at a moderate rate, iron reacts fairly slowly, and lead reacts very slowly, with the reaction quickly stopping because of the formation of an insoluble layer of lead(II) chloride or sulfate. Copper, silver and gold do not react with dilute acids.
锌反应速度适中，铁反应相当缓慢，铅反应非常慢，而且由于生成不溶的氯化铅或硫酸铅层，反应会很快停止。铜、银和金不与稀酸反应。
The table below summarises the observations when equal-sized pieces of different metals are added to dilute hydrochloric acid.
下表总结了将相同大小的不同金属片加入稀盐酸时的观察结果。
| Metal / 金属 | Observation with dilute HCl / 与稀盐酸反应的观察 | Rate / 速度 |
|---|---|---|
| Mg / 镁 | Very rapid bubbling; magnesium dissolves / 气泡极快；镁溶解 | Very fast / 非常快 |
| Al / 铝 | Bubbling after a short delay / 经过短暂延迟后冒泡 | Moderate / 中等 |
| Zn / 锌 | Steady bubbling; metal slowly disappears / 稳定冒泡；金属慢慢消失 | Moderate / 中等 |
| Fe / 铁 | Slow bubbling; pale green solution forms / 缓慢冒泡；形成浅绿色溶液 | Slow / 慢 |
| Cu / 铜 | No reaction / 无反应 | None / 无 |
Mg + 2HCl → MgCl₂ + H₂
Zn + H₂SO₄ → ZnSO₄ + H₂
Fe + 2HCl → FeCl₂ + H₂
5. Displacement Reactions between Metals | 金属间的置换反应
A more reactive metal can displace a less reactive metal from a solution of its salt. This is a key type of redox reaction and provides strong evidence for placing metals in the reactivity series.
一种更活泼的金属可以从另一种金属的盐溶液中将其置换出来。这是一类关键的氧化还原反应，为金属在活泼性顺序中的排位提供了有力证据。
When a piece of zinc is dipped into copper(II) sulfate solution, the zinc slowly darkens as a coating of copper forms, and the blue colour of the solution fades. Zinc loses electrons to form Zn²⁺ ions, while Cu²⁺ ions gain electrons to form copper atoms.
将一块锌放入硫酸铜溶液中，锌会慢慢变暗，覆盖一层铜，同时溶液的蓝色逐渐褪去。锌失去电子生成 Zn²⁺ 离子，而 Cu²⁺ 离子得到电子形成铜原子。
Similarly, iron nails placed in copper(II) sulfate become coated with a reddish-brown layer of copper, and the solution turns green due to the formation of iron(II) sulfate. No reaction occurs when copper is placed in zinc sulfate solution, confirming that copper is less reactive than zinc.
同样，将铁钉放入硫酸铜溶液中，铁钉表面会覆盖一层红褐色的铜，溶液因生成硫酸亚铁而变成浅绿色。若将铜放入硫酸锌溶液中则无反应，这证实了铜不如锌活泼。
Zn + CuSO₄ → ZnSO₄ + Cu
Fe + CuSO₄ → FeSO₄ + Cu
The most reactive metals, such as potassium, cannot be used in aqueous displacement experiments because they react directly with water rather than with the dissolved ions.
最活泼的金属（如钾）不能用于水溶液置换实验，因为它们会直接与水反应，而非与溶液中的离子发生作用。
6. Ordering Metals into the Reactivity Series | 给金属排活泼性顺序
By combining the evidence from reactions with oxygen, water and dilute acids, and from displacement reactions, we can arrange the common metals into a reactivity series. Carbon and hydrogen are often included as reference points because they play crucial roles in the extraction of metals.
综合金属与氧气、水和稀酸反应以及置换反应的证据，我们可以将常见金属排列成活泼性顺序。碳和氢常被作为参考点纳入其中，因为它们在金属提取中起着关键作用。
The complete order of reactivity, from most reactive to least reactive, is: potassium (K) > sodium (Na) > calcium (Ca) > magnesium (Mg) > aluminium (Al) > carbon (C) > zinc (Zn) > iron (Fe) > lead (Pb) > hydrogen (H) > copper (Cu) > silver (Ag) > gold (Au).
从最活泼到最不活泼的完整顺序为：钾 (K) > 钠 (Na) > 钙 (Ca) > 镁 (Mg) > 铝 (Al) > 碳 (C) > 锌 (Zn) > 铁 (Fe) > 铅 (Pb) > 氢 (H) > 铜 (Cu) > 银 (Ag) > 金 (Au)。
This order can be memorised using a mnemonic such as: 'Please Stop Calling Me A Cute Zebra, I Like Hiding Copper Silver Gold.' Metals above hydrogen displace it from acids; metals below hydrogen cannot. Similarly, oxides of metals below carbon can be reduced by heating with carbon, while those above carbon require electrolysis.
这个顺序可以用记忆口诀帮助记忆。在氢之上的金属能从酸中置换出氢气，而在氢之下的金属则不能。同样，位于碳之下的金属氧化物可以通过与碳共热被还原，而位于碳之上的金属氧化物则需要用电解法。
7. Carbon Reduction of Metal Oxides | 碳还原金属氧化物
Carbon is a cheap and effective reducing agent for extracting metals of moderate reactivity from their ores. When a metal oxide is heated with powdered carbon, the carbon removes the oxygen, leaving the metal behind.
碳是一种廉价且有效的还原剂，可用于从矿石中提取中等活泼性的金属。将金属氧化物与碳粉共热时，碳将氧夺走，留下金属。
A common laboratory demonstration involves heating a mixture of copper(II) oxide and carbon. The black powder turns into reddish-brown copper, and a colourless gas that turns limewater milky is given off, showing that carbon dioxide is produced.
常见的课堂演示是加热氧化铜和碳的混合物。黑色粉末变为红棕色的铜，并产生能使石灰水变浑浊的无色气体，证明生成了二氧化碳。
Zinc oxide and iron(III) oxide can also be reduced by carbon in a similar way. However, this method does not work for oxides of metals above aluminium in the reactivity series because these metals hold onto oxygen too strongly.
氧化锌和氧化铁也可以用类似的碳还原法处理。然而，对于活泼性顺序中排在铝以上的金属氧化物，该方法则无效，因为这些金属与氧结合过于牢固。
2CuO + C → 2Cu + CO₂
2Fe₂O₃ + 3C → 4Fe + 3CO₂
ZnO + C → Zn + CO
8. Electrolysis for Extracting Reactive Metals | 电解提取活泼金属
Metals that are more reactive than carbon, such as aluminium, cannot be extracted by carbon reduction. Instead, they are extracted from their molten compounds using electrolysis, a process that uses a direct electric current to drive an otherwise non-spontaneous reduction.
比碳更活泼的金属（如铝）无法用碳还原法提取。这些金属需要通过电解其熔融化合物来提取，电解是利用直流电驱动非自发还原反应的过程。
Aluminium is extracted from purified bauxite ore (Al₂O₃) through the Hall-Héroult process. The aluminium oxide is dissolved in molten cryolite (Na₃AlF₆) to lower its melting point from over 2000 °C to around 950 °C, reducing energy costs.
铝通过霍尔-埃鲁法从纯化后的铝土矿 (Al₂O₃) 中提取。将氧化铝溶解在熔融冰晶石 (Na₃AlF₆) 中，可将其熔点从 2000 °C 以上降低至约 950 °C，从而降低能耗。
During electrolysis, aluminium ions (Al³⁺) are reduced at the cathode to form molten aluminium, while oxide ions (O²⁻) are oxidised at the anode to give oxygen gas. The anodes are made of graphite and are gradually consumed, forming carbon dioxide.
电解过程中，铝离子 (Al³⁺) 在阴极被还原为熔融铝，而氧离子 (O²⁻) 在阳极被氧化生成氧气。阳极由石墨制成，会逐渐消耗并生成二氧化碳。
At cathode: Al³⁺ + 3e⁻ → Al
At anode: 2O²⁻ → O₂ + 4e⁻
Overall: 2Al₂O₃ → 4Al + 3O₂
9. Extraction of Iron in the Blast Furnace | 高炉炼铁
Iron sits below carbon in the reactivity series and can be extracted from its ores using carbon reduction in a blast furnace. The main ore used is haematite, which contains iron(III) oxide (Fe₂O₃).
铁在活泼性顺序中位于碳之下，可以在高炉中用碳还原法从其矿石中提取。主要使用的矿石是赤铁矿，含有氧化铁 (Fe₂O₃)。
A mixture of haematite, coke (a form of carbon) and limestone is fed into the top of the blast furnace, while a blast of hot air is blown in near the bottom. The coke burns in the hot air to produce carbon dioxide and releases enormous heat.
赤铁矿、焦炭和石灰石的混合物从高炉顶部加入，同时靠近底部吹入热空气。焦炭在热空气中燃烧生成二氧化碳，并释放出大量热量。
As the carbon dioxide rises through more coke, it is reduced to carbon monoxide. It is this carbon monoxide, not the coke itself, that reduces the iron oxide to molten iron. The iron trickles down and is tapped off from the bottom.
当二氧化碳穿过更多的焦炭上升时，被还原为一氧化碳。正是这种一氧化碳（而非焦炭本身）将氧化铁还原为熔融铁。铁水流淌到底部并被放出。
Limestone (calcium carbonate) decomposes to form calcium oxide and carbon dioxide. The calcium oxide reacts with silica (silicon dioxide), the main impurity in the ore, to form molten calcium silicate, or slag. This slag floats on top of the iron and is tapped off separately.
石灰石（碳酸钙）分解生成氧化钙和二氧化碳。氧化钙与矿石中的主要杂质二氧化硅反应，生成熔融的硅酸钙，即炉渣。炉渣浮在铁水上，可分开排出。
C + O₂ → CO₂
CO₂ + C → 2CO
Fe₂O₃ + 3CO → 2Fe + 3CO₂
CaCO₃ → CaO + CO₂
CaO + SiO₂ → CaSiO₃
10. Rusting of Iron and Methods of Prevention | 铁的锈蚀与防护
Rusting is a specific type of corrosion that only affects iron and its alloys. For rust to form, both oxygen and water must be present. Rust is a hydrated iron(III) oxide with a characteristic flaky, reddish-brown appearance that weakens the metal.
锈蚀是一种只影响铁及其合金的特定腐蚀类型。形成铁锈需要同时存在氧气和水。铁锈是一种水合氧化铁，呈特征性的红褐色片状，会削弱金属强度。
Experiments using iron nails in different conditions—such as dry air, boiled water covered with oil, and water with air—show that rusting only occurs where both water and air are freely available. Salt water accelerates rusting because the dissolved electrolytes aid electron flow.
使用铁钉在不同条件下（如干燥空气、覆盖油层的煮沸水、以及有空气的水）的实验证明，只有在水和空气同时充足存在的地方才会发生锈蚀。盐会加快锈蚀，因为溶入的电解质有助于电子流动。
Rusting can be prevented by forming a barrier that keeps out oxygen and water. Common barrier methods include painting, oiling, greasing, and coating with plastic. Galvanising involves coating iron with a layer of zinc, which acts both as a physical barrier and as a sacrificial protector because zinc is more reactive than iron.
通过形成阻挡氧气和水的屏障可以防止锈蚀。常见的屏障方法包括涂漆、涂油、涂油脂和包覆塑料。镀锌则是在铁表面镀上一层锌，既起到物理屏障作用，也作为牺牲保护，因为锌比铁更活泼。
Another method is the use of sacrificial anodes: attaching blocks of a more reactive metal, such as magnesium or zinc, to iron structures. These metals corrode in preference to the iron, protecting it even if the coating is scratched.
另一种方法是使用牺牲阳极：将更活泼的金属块（如镁或锌）连接到铁结构上。这些金属会优先腐蚀，即使涂层被刮伤也能保护铁。
11. Alloys and Their Properties | 合金及其性质
An alloy is a mixture of a metal with one or more other elements, usually other metals or carbon. Alloys are designed to have properties that are superior to those of the pure metal. The addition of different atoms disrupts the regular arrangement of atoms in the metal lattice, making it harder for layers to slide over each other.
合金是一种金属与一种或多种其他元素（通常是其他金属或碳）的混合物。合金的设计旨在获得优于纯金属的性能。不同原子的加入打乱了金属晶格中规则的原子排列，使得各层原子之间更难滑动。
Steel is the most common alloy of iron. Mild steel, containing up to 0.3% carbon, is strong and malleable and is used in car bodies and construction. High-carbon steel is harder but more brittle and is used for cutting tools. Stainless steel, containing chromium and nickel, is highly resistant to corrosion.
钢是最常见的铁合金。含碳量不超过 0.3% 的低碳钢强度高且易延展，用于汽车车体和建筑。高碳钢更硬但更脆，用于切削工具。含铬和镍的不锈钢具有极强的耐腐蚀性。
Other important alloys include brass (copper and zinc), which is used for musical instruments, and bronze (copper and tin), known for its hardness and historical significance. Aluminium alloys, made by adding copper, magnesium or silicon, are lightweight yet strong, which makes them ideal for aircraft construction.
其他重要合金包括黄铜（铜和锌），用于制作乐器；青铜（铜和锡），因其硬度和历史意义而闻名。通过加入铜、镁或硅制成的铝合金重量轻且强度高，是制造飞机的理想材料。
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