📚 Reactivity of Metals: KS3 CIE Mark Scheme Guide | 金属活动性：KS3 CIE 评分标准指南
This article breaks down how examiners award marks in KS3 CIE Science questions about the reactivity of metals. It focuses on the reactivity series, typical reactions with oxygen, water and dilute acids, displacement reactions, and the wording used in mark schemes.
本文解析 KS3 CIE 科学考试中金属活动性题目的评分方式，重点包括金属活动性顺序、金属与氧气、水和稀酸的典型反应、置换反应以及评分标准中的常见表述。
1. The Reactivity Series | 金属活动性顺序
The reactivity series lists metals in order of decreasing reactivity. For KS3 CIE, you need to know a common order: potassium > sodium > calcium > magnesium > aluminium > zinc > iron > lead > copper > silver > gold.
金属活动性顺序按反应性从强到弱排列。KS3 CIE 要求掌握常见顺序：钾 > 钠 > 钙 > 镁 > 铝 > 锌 > 铁 > 铅 > 铜 > 银 > 金。
Mark schemes often award one mark for stating the position of a metal or for selecting the more reactive metal from a pair. You should be able to compare any two metals and explain that a more reactive metal loses electrons more easily.
评分标准通常对写出金属的位置或从两种金属中选出更活泼的一方给分。你需要能够比较任意两种金属，并解释更活泼的金属更容易失去电子。
2. Reactions of Metals with Oxygen | 金属与氧气反应
Most metals react with oxygen to form metal oxides. For example, magnesium burns in air with a bright white flame to form magnesium oxide.
大多数金属与氧气反应生成金属氧化物。例如，镁在空气中燃烧发出耀眼的白光，生成氧化镁。
2Mg + O₂ → 2MgO
Mark schemes commonly give one mark for the word equation and one for the balanced symbol equation, or one mark for the observation. They also expect the product to be named as an oxide, not an element.
评分标准通常对文字表达式给一分、配平的符号方程式给一分，或对现象给一分。同时期望产物写作氧化物，而不是元素。
Some metals, such as copper, react slowly and only form a black coating of copper(II) oxide when heated. Gold and silver do not react with oxygen under normal conditions.
有些金属（如铜）反应较慢，仅在加热时生成黑色的氧化铜(II)薄层。金和银在通常条件下不与氧气反应。
3. Reactions of Metals with Water | 金属与水反应
Very reactive metals such as potassium, sodium and calcium react with cold water. Potassium and sodium react vigorously, while calcium reacts less strongly.
非常活泼的金属，如钾、钠和钙，能与冷水反应。钾和钠反应剧烈，钙反应较弱。
r → metal hydroxide + hydrogen. For example: sodium + water → sodium hydroxide + hydrogen.
一般规律为：活泼金属 + 水 → 金属氢氧化物 + 氢气。例如：钠 + 水 → 氢氧化钠 + 氢气。
2Na + 2H₂O → 2NaOH + H₂
Examiners look for the observation that the metal floats, moves on the surface, fizzes, and may melt or ignite. The gas can be tested with a burning splint; a squeaky pop confirms hydrogen.
考官关注的现象包括：金属浮在水面、四处游动、产生气泡，可能熔化或燃烧。气体可用点燃的木条检验；听到爆鸣声证明是氢气。
Metals below calcium in the reactivity series do not generally react with cold water, though magnesium reacts very slowly with steam.
活动性顺序中位于钙以下的金属通常不与冷水反应，不过镁能与水蒸气缓慢反应。
4. Reactions of Metals with Dilute Acid | 金属与稀酸反应
Many metals react with dilute hydrochloric acid or sulfuric acid to produce a salt and hydrogen gas. The salt formed depends on the acid: hydrochloric acid produces chlorides; sulfuric acid produces sulfates.
许多金属与稀盐酸或稀硫酸反应生成盐和氢气。生成的盐取决于酸：盐酸生成氯化物；硫酸生成硫酸盐。
Mg + 2HCl → MgCl₂ + H₂
The rate of reaction can be used to infer the reactivity of the metal. Bubbles of hydrogen gas appear more rapidly with magnesium than with zinc or iron.
反应速率可用于推断金属的活动性。镁与酸反应产生氢气气泡的速率比锌或铁快。
Mark schemes may ask for a balanced equation, a salt name, or a description of the test for hydrogen. A common error is confusing the salt name, such as writing magnesium chloride incorrectly or using the wrong acid radical.
评分标准可能要求配平方程式、盐的名称或氢气的检验方法。常见错误是混淆盐的名称，例如写错氯化镁或使用错误的酸根。
Copper, silver and gold do not react with dilute acids because they are below hydrogen in the reactivity series.
铜、银和金不与稀酸反应，因为它们在活动性顺序中位于氢以下。
5. Displacement Reactions | 置换反应
A more reactive metal can displace a less reactive metal from its compound in solution. For example, iron displaces copper from copper(II) sulfate solution.
活泼性较强的金属能把活泼性较弱的金属从其化合物溶液中置换出来。例如，铁能从硫酸铜(II)溶液中置换出铜。
Fe + CuSO₄ → FeSO₄ + Cu
In this reaction, the blue colour of copper(II) sulfate fades, and a brown or orange coating of copper forms on the iron. The iron nail may also lose mass as iron atoms go into solution.
该反应中，硫酸铜(II)的蓝色变浅，铁表面生成棕色或橙色的铜层。铁钉的质量可能减少，因为铁原子进入溶液。
Mark schemes reward both the observation and the word or symbol equation. They may also ask you to explain why the reaction occurs using the reactivity series.
评分标准对现象和文字/符号方程式都给分。也可能要求你利用活动性顺序解释反应发生的原因。
Displacement can also occur in carbon extraction: carbon is used to displace less reactive metals such as iron from their oxides.
置换也可用于碳还原法：碳可用于从金属氧化物中置换出铁等活泼性较弱的金属。
6. Using the Reactivity Series to Predict Reactions | 利用活动性顺序预测反应
The reactivity series allows you to predict whether a reaction will occur. If metal A is above metal B in the series, metal A will displace metal B from its salt solution.
利用活动性顺序可以预测反应是否发生。如果金属 A 在系列中位于金属 B 之上，金属 A 能把金属 B 从其盐溶液中置换出来。
For example, zinc will displace lead from lead(II) nitrate solution, but silver will not displace copper from copper(II) sulfate.
例如，锌能从硝酸铅(II)溶液中置换出铅，但银不能从硫酸铜(II)溶液中置换出铜。
Examiners often use predict and explain together. The explanation must mention the relative positions in the reactivity series, not just the observation.
考官常将预测与解释结合考查。解释必须提及两种金属在活动性顺序中的相对位置，而不是只描述现象。
In mark schemes, the phrase because zinc is more reactive than copper is a required comparison; using zinc is reactive alone usually does not earn the explanation mark.
在评分标准中，因为锌比铜更活泼是必要的比较；只说锌很活泼通常不能得到解释分。
7. Experimental Observations and Evidence | 实验现象与证据
Questions often require precise observations rather than conclusions. An observation is what you see, hear, or measure, such as bubbles form or the solution changes colour from blue to colourless.
题目常要求准确的实验现象而非结论。现象是看到、听到或测量到的内容，如产生气泡或溶液由蓝色变为无色。
The mark scheme may reject vague answers like it reacts or it changes colour without stating the starting and final colours. You should always name the colour change when known.
评分标准可能不接受发生反应或颜色改变等模糊答案，除非写出起始和最终颜色。只要知道颜色，就应写清颜色变化。
In displacement reactions, the colour change is linked to the ions: blue copper(II) ions, Cu²⁺, are reduced to copper atoms; pale green iron(II) ions, Fe²⁺, may form.
置换反应中的颜色变化与离子有关：蓝色的铜(II)离子 Cu²⁺ 被还原为铜原子；可能生成浅绿色的铁(II)离子 Fe²⁺。
Temperature change can also be evidence of reactivity. Reactions of reactive metals with water or acid are exothermic, releasing heat.
温度变化也可作为反应性的证据。活泼金属与水或酸的反应是放热的，会释放热量。
8. Mark Scheme Command Words and Common Misconceptions | 评分标准指令词与常见误区
CIE mark schemes use command words such as state, describe, explain, predict, compare, and suggest. Each requires a different depth of answer.
CIE 评分标准使用的指令词包括陈述、描述、解释、预测、比较和建议。每个词要求的答案深度不同。
State requires a short factual answer, describe requires observations or steps, and explain requires a scientific reason or mechanism.
陈述要求简短的事实性答案；描述要求现象或步骤；解释要求科学原因或机理。
Common misconceptions include: thinking all metals react with water; confusing the reactivity series with the periodic table; writing metal oxide instead of metal hydroxide for water reactions; and forgetting to balance symbol equations.
常见误区包括：认为所有金属都和水反应；把活动性顺序和元素周期表混淆；金属与水反应时写成金属氧化物而不是金属氢氧化物；以及忘记配平符号方程式。
Also, many students write copper is more reactive than iron because copper is a transition metal, but in the reactivity series copper is below iron. The mark scheme requires the correct comparison.
此外，许多学生因铜是过渡金属而写铜比铁活泼，但在活动性顺序中铜位于铁之下。评分标准要求正确比较。
When an equation is required, the mark scheme may allow one mark for correct formulae and one for balancing. If you omit state symbols at KS3, marks are not usually lost unless stated.
要求写方程式时，评分标准可能对正确化学式给一分、配平给一分。KS3 阶段如未标状态符号，通常不扣分，除非题目明确要求。
9. Sample Mark Scheme Table | 典型评分表示例
The table below shows how a KS3 CIE examiner might allocate marks for typical questions about the reactivity of metals.
下表展示了 KS3 CIE 考官可能如何对金属活动性的典型题目分配分数。
| Question | 题目 | Answer | 答案 | Marks | 分数 |
|---|---|---|
| State one observation when magnesium reacts with dilute hydrochloric acid. | 写出镁与稀盐酸反应时的一个现象。 | Bubbles of gas / effervescence; magnesium disappears / gets smaller (any one) | 气泡 / 冒泡；镁消失 / 变小（任选一个） | 1 |
| Write the word equation for magnesium + hydrochloric acid. | 写出镁 + 盐酸的文字表达式。 | magnesium + hydrochloric acid → magnesium chloride + hydrogen | 镁 + 盐酸 → 氯化镁 + 氢气 | 1 |
| Explain why copper cannot displace zinc from zinc sulfate. | 解释为什么铜不能从硫酸锌中置换出锌。 | Copper is less reactive than zinc / copper is below zinc in the reactivity series | 铜不如锌活泼 / 铜在活动性顺序中位于锌之下 | 1 |
| Complete the symbol equation: Fe + CuSO₄ → … + Cu | 完成符号方程式：Fe + CuSO₄ → … + Cu | FeSO₄ | 硫酸亚铁 | 1 |
| Sodium is added to cold water. State two observations. | 将钠加入冷水中。写出两个现象。 | floats; moves on surface; fizzes; melts into a ball; lilac flame (any two) | 浮在水面；四处游动；冒泡；熔化成小球；产生淡紫色火焰（任选两个） | 2
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