The Earth | 地球

📚 The Earth | 地球

The Earth is a dynamic planet made of rocks, water, air and living things. In chemistry, we study the Earth by looking at the materials that build it, the gases in its atmosphere, and the chemical reactions that change rocks, fuels and the climate.

地球是一个由岩石、水、空气和生物组成的动态行星。在化学中，我们通过研究构成地球的物质、大气中的气体以及改变岩石、燃料和气候的化学反应来认识地球。

1. The Structure of the Earth | 地球的结构

The Earth has a layered structure. From the outside in, the main layers are the crust, the mantle, the outer core and the inner core. The crust is the thin, solid outer layer made of rock, while the core is mainly iron and nickel.

地球具有层状结构。从外到内，主要层次是地壳、地幔、外核和内核。地壳是由岩石组成的薄而坚固的外层，而地核主要由铁和镍组成。

The crust and the upper part of the mantle form the lithosphere. Below the lithosphere, the mantle is hot and partly molten. The outer core is liquid, and the inner core is solid because of extremely high pressure.

地壳和地幔上部构成岩石圈。在岩石圈之下，地幔温度很高且部分熔融。外核是液态的，而内核由于极高的压力呈固态。

Movement of heat inside the Earth drives plate tectonics. This movement causes volcanoes and earthquakes, and it also brings new chemicals from deep inside the Earth to the surface.

地球内部的热量运动驱动板块构造。这种运动引起火山和地震，同时也会把地球深处的新化学物质带到地表。

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2. Early and Modern Atmosphere | 早期与现代大气

The Earth’s early atmosphere was formed by volcanic activity. Volcanoes released gases such as carbon dioxide, water vapour, methane and ammonia. There was very little oxygen in the early atmosphere.

地球早期的大气是由火山活动形成的。火山释放二氧化碳、水蒸气、甲烷和氨等气体。早期大气中几乎没有氧气。

As the Earth cooled, water vapour condensed to form oceans. Carbon dioxide dissolved in the oceans and was also locked up in carbonate rocks. Photosynthetic organisms later produced oxygen, which gradually increased in the atmosphere.

随着地球冷却，水蒸气凝结形成海洋。二氧化碳溶解在海洋中，并被固定在碳酸盐岩石里。后来，光合作用生物产生氧气，使大气中的氧气逐渐增加。

The modern atmosphere is about 78% nitrogen, 21% oxygen, 0.9% argon and 0.04% carbon dioxide. Water vapour is also present in variable amounts.

现代大气中约含 78% 的氮气、21% 的氧气、0.9% 的氩气和 0.04% 的二氧化碳。水蒸气的含量则变化不定。

Gas	气体	Approximate percentage
Nitrogen	氮气	78%
Oxygen	氧气	21%
Argon	氩气	0.9%
Carbon dioxide	二氧化碳	0.04%

Human activities, especially burning fossil fuels, are now increasing the amount of carbon dioxide in the atmosphere. This links the chemistry of the Earth to current climate change.

人类活动，尤其是燃烧化石燃料，正在增加大气中二氧化碳的含量。这把地球化学与当前的气候变化联系了起来。

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3. Igneous Rocks | 火成岩

Igneous rocks form when molten rock, called magma or lava, cools and solidifies. The chemical composition of the rock depends on the elements present in the magma, mainly silicon, oxygen, aluminium, iron, magnesium, calcium, sodium and potassium.

火成岩是由称为岩浆或熔岩的熔融岩石冷却凝固形成的。岩石的化学成分取决于岩浆中存在的元素，主要是硅、氧、铝、铁、镁、钙、钠和钾。

If magma cools slowly underground, large crystals have time to grow. Granite is an example of a slow-cooling igneous rock with visible crystals. If lava cools quickly on the surface, the crystals are small, as in basalt.

如果岩浆在地下缓慢冷却，大晶体就有时间生长。花岗岩是一种缓慢冷却的火成岩，具有可见的晶体。如果熔岩在地表快速冷却，晶体就很小，例如玄武岩。

Igneous rocks are often hard and resistant to weathering. Their main chemicals are silicate minerals, which contain silicon and oxygen combined with metal elements.

火成岩通常坚硬且耐风化。它们的主要化学物质是硅酸盐矿物，由硅、氧与金属元素结合而成。

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4. Sedimentary Rocks | 沉积岩

Sedimentary rocks form from sediments that are deposited in layers, compacted and cemented together. Common sediments include sand grains, clay particles, shell fragments and minerals that were dissolved in water.

沉积岩是由沉积物分层沉积、压实并胶结在一起形成的。常见的沉积物包括沙粒、黏土颗粒、贝壳碎片以及溶于水中的矿物质。

Limestone is an important sedimentary rock made mostly of calcium carbonate, CaCO₃. It often forms from the shells and skeletons of marine organisms. Sandstone is mainly grains of silica, SiO₂, cemented together, and shale forms from compacted clay minerals.

石灰岩是一种重要的沉积岩，主要由碳酸钙 CaCO₃ 组成。它通常由海洋生物的壳和骨骼形成。砂岩主要由二氧化硅 SiO₂ 颗粒胶结而成，页岩则由压实的黏土矿物形成。

Sedimentary rocks can contain fossils because they form at relatively low temperatures and pressures. Fossils are preserved remains or impressions of organisms found in the rock layers.

沉积岩中可能含有化石，因为它们是在相对较低的温度和压力下形成的。化石是保存在岩层中的生物遗骸或印痕。

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5. Metamorphic Rocks | 变质岩

Metamorphic rocks form when existing rocks are changed by heat and pressure. The original minerals may recrystallise or rearrange into new minerals without the rock melting completely.

变质岩是在热和压力作用下由原有岩石发生变化而形成的。原有的矿物可能重新结晶或重新排列成新矿物，而岩石并未完全熔化。

Limestone changes into marble under heat and pressure. Marble is still mainly calcium carbonate, CaCO₃, but its crystals are larger and interlock, making it harder and useful for sculpture and building.

石灰岩在热和压力作用下变成大理石。大理石仍然主要由碳酸钙 CaCO₃ 组成，但其晶体更大且相互嵌合，使其更坚硬，适合用于雕塑和建筑。

Shale can be changed into slate, which has thin, flat layers. The chemical composition changes little, but the physical structure becomes denser and more compact.

页岩可以变成板岩，板岩具有薄而平坦的层理。化学成分变化很小，但物理结构变得更加致密和紧实。

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6. The Rock Cycle | 岩石循环

The rock cycle describes how rocks change from one type to another over millions of years. It involves weathering, erosion, deposition, compaction, cementation, melting and cooling.

岩石循环描述了岩石在数百万年间如何从一种类型转变为另一种类型。它涉及风化、侵蚀、沉积、压实、胶结、熔融和冷却。

Igneous rocks can be weathered and eroded into sediments that later form sedimentary rocks. Sedimentary rocks can be buried and changed by heat and pressure into metamorphic rocks. Any rock can melt and then cool to form new igneous rock.

火成岩可以被风化和侵蚀成沉积物，之后形成沉积岩。沉积岩可以被埋藏并在热和压力作用下变成变质岩。任何岩石都可以熔化，然后冷却形成新的火成岩。

Weathering includes both physical breakdown and chemical reactions. For example, rainwater containing carbon dioxide is slightly acidic and can slowly dissolve limestone.

风化包括物理破碎和化学反应。例如，含有二氧化碳的雨水呈弱酸性，可以缓慢溶解石灰岩。

CaCO₃ + CO₂ + H₂O → Ca²⁺ + 2HCO₃⁻

This equation shows that limestone can be dissolved by carbonic acid formed when carbon dioxide reacts with water. The dissolved material can later precipitate to form new carbonate rocks.

该方程式表明，二氧化碳与水反应生成的碳酸可以溶解石灰岩。溶解的物质随后可能沉淀，形成新的碳酸盐岩石。

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7. Limestone and Thermal Decomposition | 石灰石与热分解

Limestone is mainly calcium carbonate, CaCO₃. When heated strongly, it undergoes thermal decomposition to form calcium oxide and carbon dioxide gas.

石灰岩的主要成分是碳酸钙 CaCO₃。当被强烈加热时，它会发生热分解，生成氧化钙和二氧化碳气体。

CaCO₃ → CaO + CO₂

This reaction is important in industry because calcium oxide, also called quicklime, is used to make cement, mortar and concrete. Thermal decomposition means breaking down a compound using heat.

这个反应在工业中很重要，因为氧化钙（也称生石灰）用于制造水泥、砂浆和混凝土。热分解是指利用热量使化合物分解。

Limestone also reacts with acids. When dilute hydrochloric acid is added to limestone, it fizzes and releases carbon dioxide gas.

石灰岩还能与酸反应。当把稀盐酸加到石灰岩上时，会产生气泡并释放二氧化碳气体。

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

This reaction is used as a test for carbonate rocks. The release of carbon dioxide gas can be tested by bubbling the gas through limewater, which turns cloudy.

这个反应用于检验碳酸盐岩石。释放出的二氧化碳气体可以通过将气体通入石灰水中来检验，石灰水会变浑浊。

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8. Fossil Fuels and Combustion | 化石燃料与燃烧

Fossil fuels include coal, oil and natural gas. They formed from the remains of dead plants and animals over millions of years. Chemically, they are mainly hydrocarbons, which are compounds made of carbon and hydrogen.

化石燃料包括煤、石油和天然气。它们是由数百万年前死去的动植物遗骸形成的。从化学角度看，它们主要是碳氢化合物，即由碳和氢组成的化合物。

When hydrocarbons burn in a good supply of oxygen, they undergo complete combustion. The products are carbon dioxide and water.

当碳氢化合物在充足的氧气中燃烧时，会发生完全燃烧。产物是二氧化碳和水。

CH₄ + 2O₂ → CO₂ + 2H₂O

Methane is the main gas in natural gas, and this equation shows its complete combustion. Incomplete combustion happens when oxygen is limited, producing toxic carbon monoxide gas and solid carbon particles.

甲烷是天然气中的主要气体，这个方程式表示了它的完全燃烧。当氧气不足时会发生不完全燃烧，产生有毒的一氧化碳气体和固体碳颗粒。

Burning fossil fuels releases stored carbon back into the atmosphere as carbon dioxide. This increases the greenhouse effect because carbon dioxide traps heat in the atmosphere.

燃烧化石燃料会将储存的碳以二氧化碳的形式释放回大气中。这会增强温室效应，因为二氧化碳会将热量留在大气中。

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9. Acid Rain | 酸雨

Acid rain is rainwater that has become more acidic than normal. It forms when gases such as sulfur dioxide, SO₂, and nitrogen oxides, NO and NO₂, dissolve in water in the atmosphere.

酸雨是酸性比正常雨水更强的雨水。当二氧化硫 SO₂ 以及氮氧化物 NO 和 NO₂ 等气体溶解在大气中的水里时，就会形成酸雨。

Sulfur dioxide is released when fossil fuels containing sulfur impurities are burned. Nitrogen oxides form at high temperatures in engines and power stations when nitrogen and oxygen from the air react.

含有硫杂质的化石燃料燃烧时会释放二氧化硫。氮氧化物则是在发动机和发电站的高温条件下，空气中的氮气和氧气发生反应形成的。

These gases dissolve in rain clouds and form sulfuric acid and nitric acid. The resulting acid rain damages buildings made of limestone, harms plants and animals, and can make lakes and soils too acidic.

这些气体溶解在雨云中，形成硫酸和硝酸。由此产生的酸雨会破坏石灰岩建筑，危害动植物，并可能使湖泊和土壤变得过酸。

Limestone buildings are affected because calcium carbonate reacts with acids. The rock slowly dissolves and crumbles, which is a serious problem for historic stone monuments.

石灰岩建筑会受到影响，因为碳酸钙会与酸反应。岩石会缓慢溶解并碎裂，这对历史石质古迹来说是一个严重问题。

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10. The Carbon Cycle | 碳循环

Carbon moves between the atmosphere, living things, oceans and rocks in the carbon cycle. In the atmosphere, carbon is mainly found as carbon dioxide gas, CO₂.

在碳循环中，碳在大气、生物、海洋和岩石之间不断移动。在大气中，碳主要以二氧化碳气体 CO₂ 的形式存在。

Plants remove carbon dioxide from the air during photosynthesis. They use it to make glucose, and oxygen is released as a product.

植物在光合作用过程中从空气中吸收二氧化碳。它们利用二氧化碳制造葡萄糖，并释放氧气作为产物。

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Animals and plants return carbon dioxide to the atmosphere through respiration. Decomposers, such as bacteria and fungi, also release carbon dioxide when they break down dead material.

动物和植物通过呼吸作用将二氧化碳释放回大气中。细菌和真菌等分解者在分解死亡物质时也会释放二氧化碳。

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Some carbon is stored for a very long time in fossil fuels and carbonate rocks. Burning fossil fuels and making cement release this stored carbon back into the carbon cycle.

一些碳以化石燃料和碳酸盐岩石的形式被长期储存。燃烧化石燃料和制造水泥会把这些储存的碳释放回碳循环中。

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11. Earth’s Natural Resources | 地球的自然资源

The Earth provides many natural resources that humans use. Some resources, such as air and water, are renewable because they are replaced by natural processes. Others, such as metal ores and fossil fuels, are non-renewable because they form extremely slowly.

地球提供了许多人类使用的自然资源。空气和水等资源是可再生的，因为它们可以由自然过程补充。金属矿石和化石燃料等其他资源是不可再生的，因为它们的形成速度极其缓慢。

Chemistry helps us extract useful materials from the Earth. Metals are extracted from ores using chemical reactions, limestone is quarried for building, and crude oil is separated into fuels and raw materials for plastics.

化学帮助我们在地球中提取有用材料。金属通过化学反应从矿石中提取，石灰岩被开采用于建筑，原油则被分离成燃料和塑料原料。

Extracting and processing resources uses energy and can damage the environment. Quarrying changes landscapes, mining produces waste rock, and burning fossil fuels adds greenhouse gases to the atmosphere.

资源的开采和加工需要消耗能源，并可能破坏环境。采石改变地貌，采矿产生废石，燃烧化石燃料会向大气中增加温室气体。

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12. Using Earth’s Resources Sustainably | 可持续利用地球资源

Sustainable use of the Earth’s resources means meeting our needs without preventing future generations from meeting theirs. The three key ideas are reduce, reuse and recycle.

可持续利用地球资源意味着满足我们当前的需求，同时不影响后代满足他们的需求。三个关键理念是减少使用、重复使用和回收利用。

Reducing means using less raw material and energy. Reusing means using an item again for the same or a different purpose. Recycling means breaking down a used material and making it into something new.

减少使用是指使用更少的原材料和能源。重复使用是指再次将物品用于相同或不同的用途。回收利用是指将用过的材料分解并制成新产品。

Recycling metals and glass saves energy and reduces the need to extract new resources. For example, recycling aluminium uses much less energy than extracting aluminium from its ore.

回收金属和玻璃可以节约能源，并减少开采新资源的需要。例如，回收铝所消耗的能源远低于从铝矿石中提取铝所需的能源。

Chemists also develop new materials and processes that are less harmful to the environment. Making decisions about resources requires balancing economic, social and environmental factors.

化学家还开发对环境影响较小的新材料和新工艺。在资源问题上做决策时，需要在经济、社会和环境因素之间取得平衡。

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Published by TutorHao | Chemistry Revision Series | aleveler.com

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