📚 Physical and Chemical Properties of Metals: Key Exam Points | 金属的物理与化学性质考点梳理
Metals are one of the most important topics in chemistry, bridging atomic structure, bonding, and electrochemistry. In this revision guide, we summarise the physical and chemical properties of metals with clear explanations tailored to A-Level exam requirements.
金属是化学中最重要的主题之一，它连接了原子结构、化学键与电化学。本复习指南紧扣 A-Level 考点，系统梳理金属的物理与化学性质，并给出清晰的解释。
1. Metallic Bonding and Physical Properties | 金属键与物理性质
Metallic bonding refers to the electrostatic attraction between a lattice of positive metal ions and a "sea" of delocalised outer electrons. This model explains most physical properties of metals.
金属键是指金属正离子晶格与“自由电子海”之间的静电引力。该模型可以解释金属的大部分物理性质。
Electrical conductivity: delocalised electrons are mobile and can carry charge when a potential difference is applied.
导电性：自由电子可移动，在电势差作用下能够传导电荷。
Thermal conductivity: free electrons transfer kinetic energy rapidly through the lattice.
导热性：自由电子在晶格中快速传递动能。
Malleability and ductility: layers of positive ions can slide over each other without breaking the metallic bond, because the electron sea is flexible.
延展性与可锻性：正离子层之间可以滑动而不破坏金属键，因为自由电子海具有灵活性。
Lustre: delocalised electrons absorb and re-emit photons across a range of wavelengths.
金属光泽：自由电子吸收并重新发射多种波长的光子。
2. Trends in Melting Point and Density | 熔点与密度的变化趋势
Across a period, metals generally show increasing melting points and densities from left to right, reaching a maximum around the middle of the d-block. This is due to additional delocalised electrons per atom and smaller atomic radii.
在同一周期中，金属的熔点和密度大致从左到右升高，在 d 区中部附近达到峰值。这是因为每个原子提供的自由电子数增多，且原子半径减小。
Down a group, for example among the alkali metals, melting points decrease because the atomic radius increases and the strength of metallic bonding decreases.
在同族中，例如碱金属，随着原子半径增大，金属键强度减弱，熔点逐渐降低。
Melting point ∝ charge density of ions + number of delocalised electrons per atom
熔点 ∝ 离子电荷密度 + 每个原子提供的自由电子数
3. The Reactivity Series | 金属活动性顺序
The reactivity series ranks metals by their tendency to lose electrons and form positive ions.
金属活动性顺序根据金属失去电子形成阳离子的倾向进行排列。
K > Na > Ca > Mg > Al > Zn > Fe > H > Cu > Ag > Au
钾 > 钠 > 钙 > 镁 > 铝 > 锌 > 铁 > 氢 > 铜 > 银 > 金
The more reactive the metal, the more easily it loses electrons and the stronger its reducing power.
金属越活泼，越容易失去电子，其还原能力越强。
Metals above hydrogen can displace hydrogen from dilute acids; metals below hydrogen cannot.
氢之前的金属能从稀酸中置换出氢气；氢之后的金属则不能。
Carbon and hydrogen are often included in the series to help predict extraction methods and displacement reactions.
碳和氢通常也被列入该序列，用于帮助判断金属的提炼方法及置换反应。
4. Reaction with Oxygen | 金属与氧气的反应
Most metals react with oxygen to form metal oxides. The ease and vigour of the reaction increase with reactivity.
大多数金属与氧气反应生成金属氧化物。金属越活泼，反应越容易发生且越剧烈。
2Mg(s) + O₂(g) → 2MgO(s)
2Mg(s) + O₂(g) → 2MgO(s)
Sodium burns rapidly in oxygen to form sodium peroxide: 2Na + O₂ → Na₂O₂.
钠在氧气中迅速燃烧生成过氧化钠：2Na + O₂ → Na₂O₂。
Iron reacts slowly in moist air to form hydrated iron(III) oxide, commonly known as rust.
铁在潮湿空气中缓慢反应，生成水合氧化铁（即铁锈）。
Aluminium forms a thin, protective oxide layer (Al₂O₃), which prevents further oxidation.
铝会形成一层致密的氧化铝（Al₂O₃）保护膜，阻止进一步氧化。
5. Reaction with Water and Steam | 金属与水及水蒸气的反应
Metals show a clear trend in their reaction with water and steam, depending on their position in the reactivity series.
根据金属在活动性顺序中的位置，它们与水及水蒸气的反应有明显规律。
Potassium, sodium, and calcium react vigorously with cold water to form hydroxides and hydrogen gas.
钾、钠和钙与冷水剧烈反应，生成氢氧化物和氢气。
Magnesium reacts very slowly with cold water but rapidly with steam: Mg + H₂O → MgO + H₂.
镁与冷水反应很慢，但与水蒸气迅速反应：Mg + H₂O → MgO + H₂。
Zinc and iron react only with steam, producing metal oxides and hydrogen.
锌和铁仅与水蒸气反应，生成金属氧化物和氢气。
Copper, silver, and gold do not react with water or steam under normal conditions.
铜、银和金在常温下不与水或水蒸气反应。
6. Reaction 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 produce a salt and hydrogen gas.
在活动性顺序中位于氢之前的金属，可与稀盐酸或稀硫酸反应生成盐和氢气。
Metal + Acid → Salt + Hydrogen
金属 + 酸 → 盐 + 氢气
Zn + 2HCl → ZnCl₂ + H₂↑.
Zn + 2HCl → ZnCl₂ + H₂↑。
Fe + H₂SO₄ → FeSO₄ + H₂↑.
Fe + H₂SO₄ → FeSO₄ + H₂↑。
Reaction with nitric acid is different because nitric acid is an oxidising agent, so hydrogen gas is generally not produced.
与硝酸的反应不同，因为硝酸具有氧化性，通常不产生氢气。
7. Redox Trends and Electrode Potentials | 氧化还原趋势与标准电极电势
Standard electrode potentials (E°) provide a quantitative measure of the reducing power of metals. A more negative E° value means the metal is more easily oxidised.
标准电极电势（E°）为金属的还原能力提供了定量衡量标准。E° 值越负，金属越容易被氧化。
E°(Zn²⁺/Zn) = −0.76 V; E°(Cu²⁺/Cu) = +0.34 V
E°(Zn²⁺/Zn) = −0.76 V；E°(Cu²⁺/Cu) = +0.34 V
Zinc therefore has a stronger tendency to lose electrons than copper. When a zinc strip is placed in copper(II) sulfate solution, zinc acts as the reductant and displaces copper.
因此，锌比铜更容易失去电子。将锌片放入硫酸铜溶液时，锌作为还原剂置换出铜。
Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)
Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)
8. Corrosion of Metals | 金属的腐蚀
Corrosion is the destructive oxidation of a metal in its environment. The rusting of iron is the most common example in exams.
腐蚀是金属在环境中的破坏性氧化。铁的生锈是考试中最常考的例子。
Rusting requires both oxygen and water. The overall process can be expressed as:
生锈需要氧气和水同时存在。整个过程可用如下方程式表示：
4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃; then Fe(OH)₃ dehydrates to Fe₂O₃·xH₂O
4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃；随后 Fe(OH)₃ 脱水生成 Fe₂O₃·xH₂O
Aluminium and chromium resist corrosion by forming a self-protecting oxide layer.
铝和铬通过形成自我保护氧化层来抵抗腐蚀。
Sacrificial protection uses a more reactive metal, such as zinc, to protect iron.
牺牲阳极保护法利用更活泼的金属（如锌）来保护铁。
9. Extraction of Metals | 金属的冶炼
The extraction method for a metal depends on its position in the reactivity series.
金属的冶炼方法取决于其在活动性顺序中的位置。
| Metal position | Extraction method |
| K, Na, Ca, Al | Electrolysis of molten compounds |
| Zn, Fe, Cu | Reduction with carbon/carbon monoxide |
| Ag, Au | Occur naturally as elements |
| 金属位置 | 冶炼方法 |
| K、Na、Ca、Al | 电解熔融化合物 |
| Zn、Fe、Cu | 用碳/一氧化碳还原 |
| Ag、Au | 以单质形式存在于自然界 |
10. Transition Metals: Unique Properties | 过渡金属的特殊性质
Transition metals are d-block elements that form at least one stable ion with a partially filled d subshell. Their unique properties are frequently tested.
过渡金属是能形成至少一种具有部分填充 d 亚层稳定离子的 d 区元素。其特殊性质是高频考点。
Variable oxidation states: for example, Fe²⁺ and Fe³⁺; Cu⁺ and Cu²⁺.
可变氧化态：例如 Fe²⁺ 和 Fe³⁺，Cu⁺ 和 Cu²⁺。
Coloured compounds: due to electronic transitions between d orbitals.
化合物有颜色：因为 d 轨道之间发生电子跃迁。
Catalytic activity: transition metals and their compounds can adsorb reactants and provide alternative reaction pathways.
催化活性：过渡金属及其化合物能吸附反应物并提供新的反应路径。
Complex formation: transition metal ions form complexes with ligands such as H₂O, NH₃, and Cl⁻.
形成配合物：过渡金属离子能与 H₂O、NH₃、Cl⁻ 等配体形成配合物。
11. Alloys | 合金
An alloy is a mixture of a metal with other elements, often with different atomic sizes. Alloys are usually harder and stronger than pure metals.
合金是一种金属与其他元素的混合物，各原子尺寸往往不同。合金通常比纯金属更硬、更强。
In a pure metal, layers of identical positive ions can slide easily. In an alloy, different-sized atoms disrupt the regular lattice, making it harder for layers to slide.
在纯金属中，相同的正离子层容易滑动。在合金中，不同尺寸的原子会破坏规则的晶格结构，使层间滑动更加困难。
Steel is an alloy of iron with carbon and sometimes other metals such as chromium or nickel.
钢是铁与碳（有时还有铬、镍等金属）形成的合金。
Brass is an alloy of copper and zinc.
黄铜是铜和锌的合金。
12. Key Points and Common Mistakes | 考点总结与常见误区
Here are the most important revision points and typical misconceptions that students often make.
以下是本主题最重要的复习要点，以及学生常犯的典型错误。
Remember the full reactivity series, including hydrogen and carbon, in order.
牢记完整的活动性顺序，包括氢和碳的位置。
Common mistake: assuming all metals react with cold water. In fact, only K, Na, and Ca react vigorously with cold water.
常见误区：认为所有金属都能与冷水反应。事实上只有钾、钠和钙能与冷水剧烈反应。
Common mistake: forgetting that aluminium is protected by an oxide layer, so it appears less reactive than expected.
常见误区：忽视铝表面氧化膜的保护作用，导致其表现出的活泼性低于预期。
Common mistake: writing Fe³⁺ when iron reacts with dilute acid. With dilute HCl or H₂SO₄, iron forms Fe²⁺, not Fe³⁺.
常见误区：铁与稀酸反应时错误写成 Fe³⁺。铁与稀盐酸或稀硫酸反应生成 Fe²⁺，而非 Fe³⁺。
Always link physical properties back to metallic bonding and link chemical properties back to the reactivity series or E° values.
始终将物理性质与金属键联系起来，将化学性质与活动性顺序或 E° 值联系起来。
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