📚 The Reactivity Series | 反应性序列
The reactivity series is a core idea in chemistry. It places metals in order of how strongly they take part in chemical reactions. By learning this order, you can explain why some metals corrode quickly, why acids bubble with some metals but not others, and how metals are extracted from their ores.
反应性序列是化学中的一个核心概念。它按金属参与化学反应的剧烈程度将金属排序。通过学习这个顺序，你可以解释为什么有些金属腐蚀很快、为什么酸与某些金属反应会冒泡而与其他金属不会，以及金属如何从矿石中提取出来。
In KS3 chemistry, the reactivity series is linked to four key types of reaction: reaction with oxygen, reaction with water, reaction with dilute acids, and displacement reactions. It also helps you understand the extraction of metals using carbon or electricity.
在 KS3 化学中，反应性序列与四类关键反应有关：与氧气反应、与水反应、与稀酸反应以及置换反应。它还能帮助你理解用碳或电提取金属的原理。
1. What Is the Reactivity Series? | 什么是反应性序列？
The reactivity series is a list of metals arranged in order of how readily they react with other substances such as oxygen, water, and dilute acids. The most reactive metals are placed at the top, and the least reactive metals are placed at the bottom.
反应性序列是将金属按照它们与氧气、水和稀酸等其他物质反应的容易程度排列的顺序表。最活泼的金属排在最上面，最不活泼的金属排在最下面。
A metal's position in the series is linked to how easily it loses electrons to form positive ions. At KS3 level you only need a simple rule: the more easily a metal loses electrons, the more reactive it is, and the higher it sits in the series.
金属在序列中的位置与它失去电子形成正离子的难易程度有关。在 KS3 阶段你只需要记住一个简单规则：金属越容易失去电子，就越活泼，在序列中排得越靠上。
This single idea explains a lot of everyday chemistry: why an old iron gate rusts but a gold ring does not, why magnesium fizzes violently in acid while copper does nothing at all, and why some metal ores can simply be heated with carbon while others need expensive electrolysis.
这一个观念能解释许多日常化学现象：为什么旧铁门会生锈而金戒指不会，为什么镁在酸中剧烈冒泡而铜毫无反应，以及为什么有些金属矿石只需与碳一起加热、而另一些却需要昂贵的电解。
2. The Order of the Reactivity Series | 反应性序列的顺序
You do not need to memorise a random list. Learn the order as a ladder from most reactive at the top to least reactive at the bottom, and add carbon and hydrogen as reference points.
你不需要死记一份随机的清单。把顺序当作一架梯子来记：最活泼的在顶端，最不活泼的在底端，并把碳和氢作为参照点加进去。
| Metal / 金属 | Symbol / 符号 | Position / 位置特点 |
| Potassium | K | Most reactive / 最活泼 |
| Sodium | Na | Very reactive / 非常活泼 |
| Calcium | Ca | Reacts with cold water / 与冷水反应 |
| Magnesium | Mg | Burns brightly / 燃烧发强光 |
| Aluminium | Al | Protected by oxide layer / 有氧化层保护 |
| Zinc | Zn | Reacts with steam / 与水蒸气反应 |
| Iron | Fe | Slow reaction / 反应较慢 |
| Carbon | C | Reference point, non-metal / 参照点，非金属 |
| Hydrogen | H | Reference point, non-metal / 参照点，非金属 |
| Copper | Cu | Unreactive / 不活泼 |
| Silver | Ag | Very unreactive / 很不活泼 |
| Gold | Au | Least reactive / 最不活泼 |
A common memory sentence in English classrooms is: 'Please Send Charlie's Monkeys And Zebras In Cages, Hopefully Copper Silver Gold.' Each first letter matches a metal in order.
英语课堂常用的记忆口诀是：'Please Send Charlie's Monkeys And Zebras In Cages, Hopefully Copper Silver Gold.' 每个首字母依次对应一种金属。
3. Why Do Metals Differ in Reactivity? | 为什么金属的活泼性不同？
All metals react by losing electrons and forming positive ions. The key question is how tightly the outer electrons are held by the nucleus. Metals with only one or two outer electrons, and with a large atomic radius, lose those electrons easily and are therefore very reactive.
所有金属都是通过失去电子、形成正离子来反应的。关键在于原子核对外层电子的束缚有多强。外层只有一两个电子、且原子半径较大的金属很容易失去这些电子，因此非常活泼。
Potassium and sodium sit at the top because they give away their single outer electron almost instantly. Copper, silver, and gold sit at the bottom because they hold their outer electrons strongly and only react under more extreme conditions.
钾和钠位于顶端，因为它们几乎瞬间就交出唯一的外层电子。铜、银、金位于底端，因为它们对外层电子束缚很强，只在更苛刻的条件下才反应。
This also explains why silver and gold are found in the ground as pure metals, while reactive metals such as sodium and calcium are always found combined with other elements in compounds.
这也解释了为什么银和金能以单质形式存在于地下，而钠、钙等活泼金属总是以化合物形式与其他元素结合在一起。
4. Reaction with Oxygen | 与氧气反应
When a metal reacts with oxygen, a metal oxide is formed. This is an oxidation reaction and a form of corrosion when it happens slowly at room temperature.
当金属与氧气反应时，会生成金属氧化物。这是一个氧化反应；如果它在室温下缓慢发生，也是一种腐蚀形式。
Potassium and sodium tarnish almost instantly in air and must be stored in oil. Magnesium burns with a brilliant white flame to form a white powder, magnesium oxide. Iron reacts slowly with damp air to form rust, and burns with orange sparks only if heated strongly first.
钾和钠在空气中几乎立刻失去光泽，必须保存在煤油中。镁燃烧发出耀眼白光，生成白色粉末氧化镁。铁在潮湿空气中缓慢反应生成铁锈，只有先强烈加热才会带着橙色火星燃烧。
Copper does not react at room temperature, but on heating it slowly turns black as copper(II) oxide forms. Silver and gold do not react with oxygen at all, which is why they keep their shine for centuries.
铜在室温下不反应，但加热后会慢慢变黑，生成氧化铜(II)。银和金完全不与氧气反应，所以它们的光泽能保持几个世纪。
2Mg + O₂ → 2MgO 4Na + O₂ → 2Na₂O 2Cu + O₂ → 2CuO
The further up a metal is in the series, the faster and more violently it reacts with oxygen.
金属在序列中的位置越靠上，它与氧气反应就越快、越剧烈。
5. Reaction with Water and Steam | 与水和水蒸气反应
Not every metal reacts with cold water. Potassium, sodium, and calcium react with cold water, producing a metal hydroxide and hydrogen gas. Potassium is so reactive that the hydrogen produced catches fire with a lilac flame.
并非所有金属都能与冷水反应。钾、钠和钙能与冷水反应，生成金属氢氧化物和氢气。钾非常活泼，生成的氢气会被点燃并发出淡紫色火焰。
Magnesium reacts extremely slowly with cold water, but reacts quickly with steam. Zinc and iron also need steam before they will react, and they form a metal oxide rather than a hydroxide.
镁与冷水反应极慢，但能与水蒸气迅速反应。锌和铁也需要水蒸气才能反应，而且生成的是金属氧化物而不是氢氧化物。
Copper, silver, and gold do not react with water or steam at all. This is the reason copper pipes and gold jewellery can be used around water without being destroyed.
铜、银和金完全不与水或水蒸气反应。这就是铜管和金饰能在潮湿环境中长期使用而不被破坏的原因。
+ 2H₂O → 2NaOH + H₂ Mg + H₂O → MgO + H₂ 3Fe + 4H₂O → Fe₃O₄ + 4H₂
The reaction with steam works best in the laboratory with a sealed tube, because steam must be kept away from the metal until the experiment begins.
在水蒸气实验中，实验室里通常使用密封管，因为在实验开始前必须让水蒸气与金属隔绝。
6. Reaction with Dilute Acids | 与稀酸反应
Metals above hydrogen in the reactivity series react with dilute acids to give a salt and hydrogen gas. The metal pushes the hydrogen out of the acid, so this is also a displacement reaction.
排位在氢之上的金属能与稀酸反应，生成盐和氢气。金属把氢从酸中置换出来，所以这也是一种置换反应。
The speed depends on position. Magnesium reacts very fast with dilute hydrochloric acid, zinc reacts steadily, and iron reacts slowly. Copper, silver, and gold do not react with dilute acids at all, so they never produce bubbles.
反应速率取决于位置。镁与稀盐酸反应非常快，锌反应平稳，铁反应缓慢。铜、银和金完全不与稀酸反应，因此从不会产生气泡。
Bubbles of hydrogen can be tested with a lit splint. If a squeaky pop is heard, hydrogen is present. Potassium, sodium, and calcium react so violently with acid that the experiment is too dangerous to do in a school laboratory.
氢气气泡可用点燃的木条检验。若听到尖锐的爆鸣声，说明有氢气。钾、钠和钙与酸反应过于剧烈，在学校实验室中做这个实验太危险。
2HCl → MgCl₂ + H₂ Zn + 2HCl → ZnCl₂ + H₂ Fe + 2HCl → FeCl₂ + H₂
In a graph of gas volume against time, magnesium produces the steepest line, zinc is in the middle, and iron is the flattest, although all three eventually produce the same volume if the acid is in excess.
在以气体体积对时间作图时，镁的曲线最陡，锌居中，铁最平缓；不过如果酸过量，三者最终产生的气体体积相同。
7. Displacement Reactions | 置换反应
A displacement reaction happens when a more reactive metal takes the place of a less reactive metal in a compound. In KS3, this is usually shown by putting a metal into a solution of a salt of another metal.
置换反应发生在较活泼金属取代化合物中较不活泼金属的位置时。在 KS3 阶段，通常用把一种金属放入另一种金属盐溶液中的方法来演示。
If zinc is placed in copper(II) sulfate solution, the blue colour fades and a pink-brown solid of copper appears. Iron does the same but more slowly, and the solution turns pale green as iron(II) sulfate forms.
把锌放入硫酸铜(II)溶液中，蓝色会褪去，并出现粉褐色的铜固体。铁也能做到，但速度更慢，同时生成硫酸铁(II)，溶液变为浅绿色。
The reverse never happens. Copper cannot displace zinc from zinc sulfate, and there is no reaction at all. This gives a simple test: no reaction means the added metal is lower in the series than the metal in the compound.
反过来绝不会发生。铜无法从硫酸锌中置换出锌，完全不反应。这给出一个简单判据：没有反应，就说明加入的金属在序列中的位置比化合物中的金属更低。
O₄ → ZnSO₄ + Cu Fe + CuSO₄ → FeSO₄ + Cu Cu + ZnSO₄ → no reaction
Displacement experiments are the classic exam question because they test both the order of the series and your ability to describe observations accurately.
置换实验是经典考题，因为它同时考查序列顺序和你准确描述实验现象的能力。
8. Extraction of Metals | 金属的提取
The reactivity series tells us the best method of extraction. Metals above carbon are too reactive to be reduced by carbon, so they must be extracted by electrolysis of their molten compounds. This uses large amounts of electricity and is expensive.
反应性序列告诉我们最佳的提取方法。排位在碳之上的金属过于活泼，无法被碳还原，因此必须通过电解其熔融化合物来提取。这需要大量电能，成本很高。
Metals below carbon, such as zinc, iron, and copper, can be extracted by heating their ores with carbon or carbon monoxide. Iron is extracted in a blast furnace, where carbon reduces iron oxide to iron and carbon dioxide is produced.
排位在碳之下的金属，如锌、铁和铜，可通过将矿石与碳或一氧化碳一起加热来提取。铁在高炉中提取，碳把氧化铁还原为铁，同时生成二氧化碳。
Silver, gold, and sometimes copper are found naturally as uncombined elements, so they need no chemical extraction at all. This is why they were the first metals used by humans.
银、金以及有时铜能以单质形式天然存在，因此完全不需要化学提取。这也是它们最早被人类使用的原因。
Fe₂O₃ + 3CO → 2Fe + 3CO₂ 2Fe₂O₃ + 3C → 4Fe + 3CO₂
The dividing line is carbon: above it, electrolysis; below it, reduction with carbon.
分界线就是碳：在碳之上用电解；在碳之下用碳还原。
9. Corrosion and Rusting | 腐蚀与生锈
Corrosion is the slow breakdown of a metal by reaction with substances in its surroundings. Iron rusts when both water and oxygen are present, forming hydrated iron(III) oxide.
腐蚀是金属与其周围物质反应而缓慢被破坏的过程。当水和氧气同时存在时，铁会生锈，生成水合氧化铁(III)。
Aluminium is above iron in the series, yet it resists corrosion well because a thin, tough layer of aluminium oxide forms instantly and seals the metal underneath. This is called a protective oxide layer.
铝在序列中位于铁之上，但它却很耐腐蚀，因为表面会立刻形成一层薄而坚韧的氧化铝，把下面的金属密封起来。这称为保护性氧化层。
Rusting can be prevented by coating the iron with paint, oil, or plastic, by galvanising it with zinc, or by connecting it to a more reactive metal. Zinc is used for galvanising because it is more reactive than iron, so zinc corrodes first and protects the iron. This is called sacrificial protection.
防止铁生锈的方法包括：用油漆、油或塑料覆盖铁；用锌镀层（镀锌）；或把铁与更活泼的金属相连。镀锌用锌，是因为锌比铁活泼，锌先被腐蚀从而保护铁。这叫做牺牲性保护。
Gold does not corrode at all because it sits at the very bottom of the series, which is why ancient gold objects still look new.
金完全不腐蚀，因为它位于序列的最底端，所以古代金器至今仍像新的一样。
10. Predicting Reactions and Writing Equations | 预测反应与书写方程式
Exam questions often ask you to predict whether a reaction will happen. Follow three steps: identify the two metals involved, decide which one is more reactive, and then say whether displacement is possible.
考题常要求你预测反应能否发生。按三步走：找出涉及的两种金属，判断哪一个更活泼，然后说明置换能否发生。
Word equations come first, then symbol equations with state symbols. Remember that hydrogen gas is written as H₂, oxygen as O₂, and that ionic compounds need charges balanced.
先写文字方程式，再写带状态符号的符号方程式。记住氢气写作 H₂，氧气写作 O₂，离子化合物的电荷必须配平。
A useful check is that the total charge on each side must be zero for a balanced equation, and the number of atoms of each element must be the same on both sides.
一个有用的检查方法是：配平的方程式两边总电荷必须为零，且每种元素的原子数在两边必须相同。
11. Common Exam Questions and Mistakes | 常见考题与常见错误
Typical questions ask you to place metals in order, describe observations, explain why a reaction does or does not occur, name the products, and choose an extraction method.
典型题目要求你给金属排序、描述实验现象、解释反应为何发生或不发生、写出产物名称，以及选择提取方法。
Observation language / 现象描述：use 'fizzes', 'bubbles', 'dissolves', 'turns black', 'glows', not vague words like 'reacts a bit'.
要使用 'fizzes'（嘶嘶冒泡）、'bubbles'（冒气泡）、'dissolves'（溶解）、'turns black'（变黑）、'glows'（发光）等词，不要用 'reacts a bit' 这类模糊说法。
Hydrogen test / 氢气检验：a lit splint gives a squeaky pop; a glowing splint relighting means oxygen.
点燃的木条发出尖锐爆鸣声说明是氢气；带火星的木条复燃说明是氧气。
Copper and acid / 铜与酸：copper is below hydrogen, so no reaction and no bubbles, however long you wait.
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