📚 3. Non-metal Elements: Properties, Reactions and Uses | 非金属元素：性质、反应与用途
In KS3 chemistry, elements are divided into two large families: metals and non-metals. Non-metal elements are found on the right-hand side of the periodic table, and they show a wide range of physical states and chemical behaviours. This article reviews the key ideas you need to know about non-metal elements, including their properties, common examples, reactions and uses, and it adds the detail that exam questions often test.
在 KS3 化学中，元素分为两大家族：金属和非金属。非金属元素位于周期表的右侧，它们表现出多种多样的物理状态和化学行为。本文回顾你需要掌握的非金属元素的关键知识，包括它们的性质、常见例子、反应和用途，并补充考试中经常考查的细节。
1. What Are Non-metal Elements? | 什么是非金属元素？
A non-metal element is an element that does not show the typical properties of a metal. Non-metals are poor conductors of heat and electricity, and they are usually dull in appearance. About 17 elements are classified as non-metals, including hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur and chlorine.
非金属元素是不表现出金属典型性质的一类元素。非金属通常导热和导电性差，外观暗淡无光泽。大约有 17 种元素被归类为非金属，包括氢、碳、氮、氧、磷、硫和氯。
At room temperature, non-metals can exist as gases (such as oxygen and nitrogen), as a liquid (bromine), or as solids (such as carbon and sulfur). Their varied states make them very useful in everyday life.
在室温下，非金属可以是气体（如氧气和氮气）、液体（溴）或固体（如碳和硫）。它们多样的状态使它们在日常生活中非常有用。
The simplest way to recognise a non-metal is to think about behaviour rather than colour or state. A non-metal does not conduct electricity, is not malleable, is not ductile, and does not make a ringing sound when struck. These differences are all linked to the way electrons are arranged and shared in the element.
识别非金属最简单的方法不是看颜色或状态，而是看行为。非金属不导电、没有延展性、不能锤打成薄片，敲击时也不会发出清脆的响声。这些差异都与元素中电子的排列和共享方式有关。
2. Position in the Periodic Table | 在周期表中的位置
Non-metals are located on the right-hand side of the periodic table. Hydrogen is the exception because it is placed at the top left, but it is still a non-metal. The non-metals include elements in groups 14 to 18, such as carbon, nitrogen, oxygen, fluorine and chlorine.
非金属位于周期表的右侧。氢是例外，因为它被放在左上角，但它仍然是非金属。非金属包括第 14 族到第 18 族的元素，例如碳、氮、氧、氟和氯。
A rough dividing line runs diagonally from boron to astatine. Elements close to this line, such as silicon and germanium, are called metalloids because they have properties between those of metals and non-metals. Everything to the right of the line is a non-metal, and everything to the left is a metal.
一条大致的分界线从硼斜向延伸到砹。靠近这条线的元素，例如硅和锗，被称为类金属，因为它们的性质介于金属和非金属之间。分界线右侧的元素是非金属，左侧的元素是金属。
Group 18, the noble gases, are all non-metals. Group 17, the halogens, are all non-metals. Group 16 contains oxygen and sulfur, and group 15 contains nitrogen and phosphorus. Carbon, in group 14, is also a non-metal, although diamond and graphite look and behave very differently from each other.
第 18 族的稀有气体全部是非金属。第 17 族的卤素全部是非金属。第 16 族包含氧和硫，第 15 族包含氮和磷。第 14 族的碳也是非金属，尽管金刚石和石墨的外观与行为彼此差异很大。
3. Physical Properties of Non-metals | 非金属的物理性质
Non-metals are poor conductors of heat and electricity. This makes them useful as insulators. Plastic handles on cooking pans, rubber coatings on wires, and the air gap in double glazing all rely on non-metal materials that do not conduct heat easily.
非金属的导热性和导电性都很差。这使它们可用作绝缘体。锅具的塑料把手、电线外层的橡胶，以及双层玻璃中的空气层，都依赖不易导热的非金属材料。
Solid non-metals are usually dull and brittle. They break or shatter when hit instead of bending. They are not malleable, so they cannot be hammered into thin sheets, and they are not ductile, so they cannot be pulled into wires.
固态非金属通常暗淡且易碎。受到敲击时它们会断裂或破碎，而不是弯曲。它们没有延展性，因此不能锤打成薄片；也没有韧性，因此不能拉成细丝。
Most non-metals have low melting points and low boiling points because they exist as simple molecules held together by weak intermolecular forces. Oxygen, nitrogen, hydrogen and chlorine are gases at room temperature for this reason. Sulfur and iodine are solids, but they still melt at fairly low temperatures.
大多数非金属的熔点和沸点较低，因为它们以简单分子的形式存在，分子之间只有较弱的分子间作用力。氧、氮、氢和氯在室温下是气体，原因就在于此。硫和碘是固体，但它们的熔点仍然相当低。
There are important exceptions. Diamond and graphite are giant covalent structures, so they have very high melting points. Graphite is also unusual because it conducts electricity, even though it is a non-metal. This exception is often tested in exams.
也有重要的例外。金刚石和石墨是巨型共价结构，因此熔点非常高。石墨还很特殊，因为尽管它是非金属，却能导电。这一例外在考试中经常出现。
Non-metals are not sonorous. Metals make a ringing sound when struck, but non-metals do not. Non-metals also generally have low density, which is why gases such as helium and hydrogen are used in balloons.
非金属没有金属响声。金属被敲击时会发出清脆的声音，非金属则不会。非金属的密度通常也较低，因此氦和氢等气体可用于填充气球。
4. States of Matter at Room Temperature | 室温下的物质状态
One of the most interesting features of non-metals is that they appear in all three states of matter at room temperature. Most are gases, a few are solids, and exactly one common non-metal is a liquid.
非金属最有趣的特点之一是，它们在室温下可以出现在物质的三种状态中。大多数是气体，少数是固体，而恰好有一种常见非金属是液体。
Non-metal states at room temperature: gas → solid → liquid
非金属在室温下的状态：气态 → 固态 → 液态
| State | 状态 | Examples | 例子 | Key point | 要点 |
| Gas | 气体 | oxygen O₂, nitrogen N₂, hydrogen H₂, chlorine Cl₂, fluorine F₂ | Particles are far apart and move freely | 粒子间距大，可自由运动 |
| Liquid | 液体 | bromine Br₂ | The only common liquid non-metal | 唯一常见的液态非金属 |
| Solid | 固体 | carbon C, sulfur S, phosphorus P, iodine I₂ | Particles are closely packed and vibrate | 粒子紧密排列并振动 |
Bromine is a dark red-brown liquid that gives off an orange vapour. It is often used in exam questions because students wrongly assume that all non-metals are gases. Mercury, by contrast, is the only common metal that is a liquid at room temperature.
溴是一种深红棕色液体，会放出橙色蒸气。考试中经常考查它，因为学生常错误地认为所有非金属都是气体。相比之下，汞是唯一在室温下呈液态的常见金属。
5. Chemical Properties and Reactions | 化学性质与反应
Non-metals tend to gain electrons when they react. By gaining electrons, a non-metal atom forms a negative ion, called an anion. For example, a chlorine atom gains one electron to form a chloride ion, and an oxygen atom gains two electrons to form an oxide ion.
非金属在反应中倾向于获得电子。通过获得电子，非金属原子形成带负电的离子，称为阴离子。例如，氯原子获得一个电子形成氯离子，氧原子获得两个电子形成氧离子。
Cl + e⁻ → Cl⁻ O + 2e⁻ → O²⁻
When a non-metal reacts with a metal, the metal loses electrons and the non-metal gains them. The oppositely charged ions are held together by strong electrostatic forces, forming an ionic compound. Sodium chloride is a familiar example.
当非金属与金属反应时，金属失去电子，非金属获得电子。带相反电荷的离子通过强大的静电作用力结合在一起，形成离子化合物。氯化钠就是一个熟悉的例子。
2Na + Cl₂ → 2NaCl 2Mg + O₂ → 2MgO
When two non-metals react together, they usually share electrons and form covalent compounds. Carbon burning in oxygen, hydrogen burning in oxygen, and nitrogen combining with hydrogen are all examples of non-metal to non-metal reactions.
当两种非金属相互反应时，它们通常共享电子并形成共价化合物。碳在氧气中燃烧、氢在氧气中燃烧，以及氮与氢结合，都是非金属与非金属反应的例子。
C + O₂ → CO₂ 2H₂ + O₂ → 2H₂O N₂ + 3H₂ ⇌ 2NH₃
Non-metal oxides are usually acidic. Carbon dioxide dissolves in water to form a weak acid, and sulfur dioxide does the same. This contrasts with metal oxides, which are usually basic and neutralise acids.
非金属氧化物通常是酸性的。二氧化碳溶于水形成弱酸，二氧化硫也是如此。这与金属氧化物形成对比，金属氧化物通常是碱性的，能中和酸。
CO₂ + H₂O ⇌ H₂CO₃ SO₂ + H₂O ⇌ H₂SO₃
Not all non-metals are equally reactive. Nitrogen is very unreactive because its atoms are joined by a strong triple bond, so the Haber process needs a high temperature, a high pressure and an iron catalyst. Fluorine and chlorine, on the other hand, are highly reactive.
并非所有非金属的活泼性都相同。氮非常不活泼，因为它的原子之间由强大的三键连接，因此哈伯法需要高温、高压和铁催化剂。相反，氟和氯则非常活泼。
6. Common Non-metal Elements and Their Uses | 常见非金属元素及其用途
Oxygen makes up about 21% of the air. It is needed for respiration and combustion. It is used in hospitals for patients who struggle to breathe, in steel making, and in oxy-acetylene welding torches.
氧气约占空气体积的 21%。呼吸作用和燃烧都需要氧气。它用于医院中呼吸困难的患者、炼钢，以及氧乙炔焊接炬。
Nitrogen makes up about 78% of the air. It is used in food packaging to keep food fresh, because it is unreactive and stops oxidation. Liquid nitrogen is used to freeze food and to store biological samples at very low temperatures.
氮气约占空气体积的 78%。它用于食品包装以保持食物新鲜，因为它不活泼并能阻止氧化。液氮用于冷冻食品，并在极低温度下保存生物样本。
Carbon exists in several forms, called allotropes. Diamond is the hardest natural substance and is used in cutting tools and drill tips. Graphite is soft and slippery, so it is used in pencils and as a lubricant. Charcoal and coke are used as fuels and in metal extraction.
碳以多种形式存在，称为同素异形体。金刚石是最硬的天然物质，用于切割工具和钻头。石墨柔软滑腻，因此用于铅笔和润滑剂。木炭和焦炭用作燃料，也用于金属冶炼。
Sulfur is a yellow solid. Most of it is converted into sulfuric acid, which is one of the most important industrial chemicals. Sulfur is also used to vulcanise rubber, making it harder and more elastic, and in some medicines and fungicides.
硫是一种黄色固体。大部分硫被转化为硫酸，硫酸是最重要的工业化学品之一。硫还用于硫化橡胶，使其更坚硬、更有弹性，也用于某些药物和杀菌剂。
Chlorine is a greenish-yellow gas. It is used to disinfect drinking water and swimming pools. It is also used to make bleach, hydrochloric acid and plastics such as PVC. Hydrogen is used in fuel cells, in the manufacture of ammonia, and in the hydrogenation of vegetable oils.
氯是一种黄绿色气体。它用于给饮用水和游泳池消毒。它还用于制造漂白剂、盐酸和聚氯乙烯等塑料。氢用于燃料电池、氨的制造，以及植物油氢化。
Phosphorus is used in fertilisers and matches. Iodine is used as an antiseptic and as a test for starch. Helium is used in balloons and to cool magnets in MRI scanners. Neon is used in glowing advertising signs.
磷用于肥料和火柴。碘用作消毒剂和淀粉的检验试剂。氦用于气球，也用于冷却核磁共振扫描仪中的磁体。氖用于发光的广告灯牌。
7. Group 17: The Halogens | 第 17 族：卤素
The halogens are the non-metals in group 17: fluorine, chlorine, bromine, iodine and astatine. They all have seven electrons in their outer shell, so they need to gain one electron to achieve a full outer shell.
卤素是第 17 族的非金属：氟、氯、溴、碘和砹。它们的最外层都有七个电子，因此需要获得一个电子才能达到满外层。
Their physical states change down the group. Fluorine is a pale yellow gas, chlorine is a greenish-yellow gas, bromine is a red-brown liquid, and iodine is a dark grey solid. Melting and boiling points increase down the group as the molecules become larger.
它们的物理状态沿族向下发生变化。氟是淡黄色气体，氯是黄绿色气体，溴是红棕色液体，碘是深灰色固体。随着分子变大，熔点和沸点沿族向下升高。
Reactivity decreases down the group. Fluorine is the most reactive non-metal, while iodine is much less reactive. A more reactive halogen can displace a less reactive halogen from its compound.
活泼性沿族向下减弱。氟是最活泼的非金属，而碘的活泼性则低得多。较活泼的卤素可以把较不活泼的卤素从其化合物中置换出来。
Cl₂ + 2KBr → 2KCl + Br₂
This displacement reaction is easy to see because the colour changes. Colourless potassium bromide solution turns orange-brown as bromine is produced. This is a common practical question in KS3 and GCSE chemistry.
这种置换反应很容易通过颜色变化观察到。无色的溴化钾溶液会变成橙棕色，因为生成了溴。这是 KS3 和 GCSE 化学中常见的实验题。
8. Group 18: The Noble Gases | 第 18 族：稀有气体
The noble gases are helium, neon, argon, krypton and xenon. They are all non-metals and they are all colourless gases at room temperature. They exist as single atoms, not as molecules, so they are described as monatomic.
稀有气体包括氦、氖、氩、氪和氙。它们都是非金属，在室温下都是无色气体。它们以单原子形式存在，而不是分子，因此被称为单原子气体。
Noble gases are extremely unreactive because they already have a full outer shell of electrons. This stable arrangement means they do not need to gain, lose or share electrons. Helium has two electrons in its outer shell, and the others have eight.
稀有气体极不活泼，因为它们已经拥有满外层电子。这种稳定结构意味着它们不需要获得、失去或共享电子。氦的最外层有两个电子，其他稀有气体则有八个。
Their lack of reactivity makes them useful. Argon is used inside light bulbs and in welding to stop hot metals reacting with oxygen. Helium is used in balloons and airships because it is less dense than air and does not burn. Neon produces a red-orange glow in discharge tubes.
它们不易反应的特点使它们很有用。氩用于灯泡内和焊接中，防止热金属与氧气反应。氦用于气球和飞艇，因为它比空气密度小且不会燃烧。氖在放电管中会发出红橙色光。
Krypton and xenon are used in high-performance lamps and flash photography. Xenon is also used in some car headlights. Noble gases are sometimes called inert gases for the same reason.
氪和氙用于高性能灯和闪光摄影。氙还用于某些汽车前照灯。出于同样的原因，稀有气体有时也被称为惰性气体。
9. Structure and Bonding in Non-metal Substances | 非金属物质的结构与键合
Many non-metal substances are simple molecular. Oxygen, nitrogen, chlorine, water and carbon dioxide are all made of small molecules. The atoms inside each molecule are held together by strong covalent bonds, but the forces between different molecules are weak.
许多非金属物质是简单分子。氧、氮、氯、水和二氧化碳都由小分子构成。每个分子内部的原子由强共价键连接，但不同分子之间的作用力很弱。
This structure explains their low melting and boiling points. When a simple molecular substance melts or boils, only the weak intermolecular forces are broken. The covalent bonds inside the molecules stay intact. This is why oxygen and nitrogen are gases at room temperature.
这种结构解释了它们低熔点和低沸点的原因。简单分子物质熔化或沸腾时，只破坏较弱的分子间作用力，分子内部的共价键保持不变。这就是氧和氮在室温下是气体的原因。
Some non-metals form giant covalent structures. Diamond, graphite and silicon dioxide are examples. In these structures, strong covalent bonds extend throughout the whole substance, so melting points are extremely high.
有些非金属形成巨型共价结构。金刚石、石墨和二氧化硅就是例子。在这些结构中，强共价键延伸到整个物质，因此熔点极高。
Graphite is arranged in layers of hexagonal rings. Each carbon atom forms three covalent bonds, leaving one delocalised electron per atom. These delocalised electrons can move, so graphite conducts electricity. Diamond has each carbon atom bonded to four others in a rigid tetrahedral network, so it does not conduct electricity.
石墨由六边形环状层排列而成。每个碳原子形成三个共价键，每个原子留下一个离域电子。这些离域电子可以移动，因此石墨能导电。金刚石中每个碳原子与另外四个碳原子在刚性四面体网络中成键，因此不导电。
Silicon is a metalloid, not a true non-metal, but it forms a giant covalent structure similar to diamond. This is why silicon is used in computer chips and solar cells. The structure explains both its hardness and its semiconducting behaviour.
硅是类金属，不是真正的非金属，但它形成与金刚石类似的巨型共价结构。这就是硅用于计算机芯片和太阳能电池的原因。这种结构解释了它的硬度以及半导体行为。
10. Non-metal Compounds in Everyday Life | 日常生活中的非金属化合物
Water is a compound of two non-metals, hydrogen and oxygen. It is essential for life, acts as a solvent for many substances, and has an unusually high boiling point for such a small molecule because of hydrogen bonding between molecules.
水是由两种非金属氢和氧组成的化合物。它对生命至关重要，可作为许多物质的溶剂，并且由于分子间存在氢键，对于如此小的分子来说，它的沸点异常高。
2H₂ + O₂ → 2H₂O
Carbon dioxide is another important non-metal compound. It is produced when carbon or carbon-containing fuels burn, and it is released during respiration. It is used in fizzy drinks, fire extinguishers and dry ice for cooling.
二氧化碳是另一种重要的非金属化合物。碳或含碳燃料燃烧时会产生二氧化碳，呼吸作用也会释放二氧化碳。它用于碳酸饮料、灭火器和干冰制冷。
Ammonia is made from nitrogen and hydrogen in the Haber process. It is a key raw material for fertilisers, which help crops grow. Without ammonia-based fertilisers, it would be much harder to feed the world's population.
氨由氮和氢通过哈伯法制造。它是肥料的关键原料，有助于农作物生长。没有氨类肥料，养活世界人口会困难得多。
Acids such as hydrochloric acid, sulfuric acid and nitric acid are all based on non-metals. Hydrochloric acid contains hydrogen and chlorine. Sulfuric acid contains hydrogen, sulfur and oxygen. Nitric acid contains hydrogen, nitrogen and oxygen. These acids are widely used in industry and in the laboratory.
盐酸、硫酸和硝酸等酸都以非金属为基础。盐酸含氢和氯。硫酸含氢、硫和氧。硝酸含氢、氮和氧。这些酸在工业和实验室中广泛使用。
Plastics and polymers are also based on non-metal compounds, mainly carbon and hydrogen. The carbon atoms form long chains that can be moulded into bottles, bags, pipes and clothing fibres. This is one reason why carbon chemistry is studied separately as organic chemistry.
塑料和聚合物也以非金属化合物为基础，主要是碳和氢。碳原子形成长链，可以塑造成瓶子、袋子、管道和衣物纤维。这也是碳化学
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