📚 Year 8 SQA Chemistry: Core Knowledge Review | Year 8 SQA 化学：核心知识点梳理
Year 8 chemistry under the Scottish Curriculum for Excellence builds a vital foundation for understanding how substances behave, interact, and transform. This article brings together the essential topics you will encounter, from particle theory and atomic structure to chemical reactions, acids and alkalis, and Earth's materials. Each section explains key ideas clearly, pairing English and Chinese explanations so that you can strengthen both your scientific vocabulary and conceptual grasp. Use this guide as your revision companion to stay confident and well-prepared.
在苏格兰卓越课程框架下，八年级化学为你理解物质的行为、相互作用和变化打下重要基础。这篇文章汇集了你将接触的核心主题，从粒子理论、原子结构到化学反应、酸碱以及地球的物质。每个部分都用清晰的中英双语解释关键概念，帮助你同时加强科学词汇和概念理解。请把这份指南当作你的复习伴侣，保持自信，做好充分准备。
1. States of Matter and Particle Theory | 物质状态与粒子理论
All matter is made up of tiny particles that are constantly moving. In solids, particles are packed closely in a fixed arrangement and only vibrate in place. In liquids, particles are still close but can slide past each other, allowing the liquid to flow. In gases, particles are far apart, move quickly and randomly, and fill any container.
所有物质都由不断运动的微小粒子组成。固体中的粒子紧密排列在固定位置上，只能原地振动。液体中的粒子仍然紧靠，但可以相互滑动，使液体能够流动。气体中的粒子相距很远，快速而无规则地运动，并充满任何容器。
Changes of state happen when a substance is heated or cooled. Melting (solid to liquid) and boiling (liquid to gas) require energy, while condensing (gas to liquid) and freezing (liquid to solid) release energy. Diffusion is the movement of particles from an area of high concentration to low concentration, and it is fastest in gases.
当物质被加热或冷却时，就会发生状态变化。熔化（固体变液体）和沸腾（液体变气体）需要能量，而冷凝（气体变液体）和凝固（液体变固体）则释放能量。扩散是粒子从高浓度区域向低浓度区域的运动，它在气体中最快。
| State / 状态 | Particle arrangement / 粒子排列 | Movement / 运动 |
|---|---|---|
| Solid / 固体 | Regular, very close / 规则，紧密 | Vibrate about fixed positions / 在固定位置振动 |
| Liquid / 液体 | Random, close / 无规则，紧密 | Slide past each other / 相互滑动 |
| Gas / 气体 | Random, far apart / 无规则，相距很远 | Fast and random in all directions / 快速无规则 |
2. Elements, Compounds, and Mixtures | 元素、化合物和混合物
An element is a pure substance made of only one type of atom. For example, oxygen gas (O₂) and iron (Fe) are elements. A compound contains two or more different types of atom chemically joined together, like water (H₂O) or carbon dioxide (CO₂). A mixture is made of different substances that are not chemically combined, such as air or sand and salt.
元素是一种只由一种原子组成的纯净物。例如，氧气 (O₂) 和铁 (Fe) 就是元素。化合物含有两种或多种不同原子通过化学键结合而成，如水 (H₂O) 或二氧化碳 (CO₂)。混合物由不同物质组成，它们没有通过化学结合在一起，例如空气或者沙子和盐的混合。
Compounds always have a fixed composition and can only be separated into their elements by chemical reactions. Mixtures can be separated by physical methods like filtration, evaporation, or distillation. The properties of a compound are different from the properties of the elements that make it.
化合物总是具有固定的组成，并且只能通过化学反应才能分解成元素。混合物则可以通过过滤、蒸发或蒸馏等物理方法进行分离。化合物的性质与其组成元素的性质不同。
3. Atoms and the Periodic Table | 原子与元素周期表
An atom consists of a tiny nucleus containing protons and neutrons, surrounded by electrons moving in shells. Protons have a positive charge (+1), electrons have a negative charge (−1), and neutrons have no charge. The atomic number is the number of protons, which determines the element. The mass number is the total number of protons plus neutrons.
原子由一个微小的原子核（含有质子和中子）以及绕核运动的电子组成。质子带一个正电荷 (+1)，电子带一个负电荷 (−1)，中子不带电。原子序数就是质子数，它决定了元素的种类。质量数是质子数加中子数的总和。
Electrons occupy shells around the nucleus. The first shell holds up to 2 electrons, the second up to 8, and the third also up to 8 for the first 20 elements. The periodic table arranges elements in order of increasing atomic number. Elements in the same group (vertical column) have similar chemical properties because they have the same number of electrons in their outermost shell.
电子分布在原子核外的电子层中。第一层最多容纳 2 个电子，第二层最多容纳 8 个，对于前 20 种元素，第三层最多也容纳 8 个。元素周期表按照原子序数递增的顺序排列。同一族（纵列）的元素具有相似的化学性质，因为它们最外层电子数目相同。
Sodium atom electron arrangement: Na 2,8,1 / 钠原子的电子排布：Na 2,8,1
4. Chemical Formulas and Equations | 化学式与化学方程式
A chemical formula uses symbols and numbers to show the types and numbers of atoms in a compound. For example, CO₂ has one carbon atom and two oxygen atoms. H₂SO₄ contains two hydrogen, one sulfur, and four oxygen atoms. The small numbers (subscripts) indicate how many atoms of each element are present.
化学式用符号和数字表示化合物中原子的种类和个数。例如，CO₂ 有一个碳原子和两个氧原子。H₂SO₄ 含有两个氢原子、一个硫原子和四个氧原子。下标数字表示每种元素的原子个数。
A balanced chemical equation represents a chemical reaction. The number of atoms of each element must be the same on both sides of the arrow because atoms are never lost or made in a chemical reaction. For instance, the reaction between magnesium and oxygen is: 2Mg + O₂ → 2MgO.
配平的化学方程式表示一个化学反应。箭号两边每种元素的原子数目必须相等，因为在化学反应中原子既不会消失也不会凭空产生。例如，镁与氧气的反应：2Mg + O₂ → 2MgO。
d to be able to write word equations and simple symbol equations to describe the reactions you study in Year 8.
文字方程式给出反应物和生成物的名称，例如：镁 + 氧气 → 氧化镁。在八年级你需要能够书写文字方程式和简单的符号方程式来描述所学的反应。
5. Acids and Alkalis | 酸和碱
Acids are substances that release hydrogen ions (H⁺) when dissolved in water. Common laboratory acids include hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and nitric acid (HNO₃). They have a sour taste (never taste in the lab!) and turn blue litmus paper red. Alkalis are soluble bases that release hydroxide ions (OH⁻) in water, such as sodium hydroxide (NaOH). They feel slippery and turn red litmus paper blue.
酸是溶于水时释放出氢离子 (H⁺) 的物质。实验室常见的酸有盐酸 (HCl)、硫酸 (H₂SO₄) 和硝酸 (HNO₃)。它们有酸味（绝不可在实验室品尝！），并能将蓝色石蕊试纸变红。碱是可溶的碱性物质，在水中释放出氢氧根离子 (OH⁻)，例如氢氧化钠 (NaOH)。碱有滑腻感，能将红色石蕊试纸变蓝。
Indicators are substances that change colour in acids and alkalis. Litmus is red in acid and blue in alkali. Universal indicator shows a full range of colours depending on the strength of the acid or alkali; it can give a pH value from 0 to 14.
指示剂是一些在酸和碱中会变色的物质。石蕊在酸中呈红色，在碱中呈蓝色。通用指示剂则根据酸碱的强弱显示一整段颜色范围，能够给出 0 到 14 的 pH 值。
6. Neutralisation and the pH Scale | 中和反应与 pH 标度
ample: HCl + NaOH → NaCl + H₂O. The H⁺ ions from the acid react with the OH⁻ ions from the alkali to form water molecules.
中和反应是酸和碱之间的反应，生成盐和水。一般方程式为：酸 + 碱 → 盐 + 水。例如：HCl + NaOH → NaCl + H₂O。酸中的 H⁺ 离子与碱中的 OH⁻ 离子结合生成水分子。
The pH scale measures how acidic or alkaline a solution is. A pH less than 7 is acidic, exactly 7 is neutral, and greater than 7 is alkaline. Strong acids have a very low pH (e.g. 1), while strong alkalis have a very high pH (e.g. 14). Everyday neutralisation includes using lime to treat acidic soil and antacid tablets to relieve indigestion.
pH 标度用来衡量溶液的酸碱度。pH 小于 7 为酸性，刚好等于 7 为中性，大于 7 为碱性。强酸的 pH 值很低（例如 1），而强碱的 pH 值很高（例如 14）。日常生活中的中和反应包括用石灰处理酸性土壤以及用抗酸药片缓解消化不良。
pH scale: 0–6 acidic, 7 neutral, 8–14 alkaline / pH 标度：0–6 酸性，7 中性，8–14 碱性
7. Metals, Non-metals, and Reactivity | 金属、非金属与反应性
Metals are typically shiny, good conductors of heat and electricity, malleable, and ductile. Non-metals are usually dull, poor conductors, and brittle when solid. The periodic table has a rough dividing line: metals are on the left and centre, while non-metals are on the right.
金属通常有光泽，是热和电的良导体，具有延展性和可锻性。非金属通常暗淡无光，是热和电的不良导体，固态时质脆。周期表有一条大致分界线：金属在左侧和中部，非金属在右侧。
ive. In Year 8 you will investigate reactions of metals with water, acid, and oxygen. For example, metals like magnesium react vigorously with hydrochloric acid to produce hydrogen gas and a salt: Mg + 2HCl → MgCl₂ + H₂.
金属活动性顺序按照金属反应的活泼程度排列。钾和钠非常活泼，铜和金则很不活泼。在八年级你将探究金属与水、酸和氧气的反应。例如，像镁这样的金属与盐酸剧烈反应，生成氢气和盐：Mg + 2HCl → MgCl₂ + H₂。
The formation of metal oxides when metals react with oxygen is an oxidation reaction. Rusting of iron is a specific example that requires both oxygen and water.
金属与氧气反应生成金属氧化物，属于氧化反应。铁生锈是一个特例，需要氧气和水同时存在。
8. Oxidation and Combustion | 氧化与燃烧
Oxidation originally meant a reaction in which a substance combines with oxygen. Burning, or combustion, is a rapid oxidation that releases heat and light. For combustion to take place, three things are needed: a fuel, oxygen, and heat (the fire triangle). Removing any one of these will extinguish the fire.
氧化最初指物质与氧结合的反应。燃烧是快速的氧化反应，会释放出热和光。燃烧需要三个条件：燃料、氧气和热量（火三角）。移除其中任何一项都能使火焰熄灭。
gen: CH₄ + 2O₂ → CO₂ + 2H₂O. Incomplete combustion, which occurs when oxygen supply is limited, produces carbon monoxide or carbon (soot), which can be dangerous.
碳氢化合物（含碳和氢的燃料）完全燃烧生成二氧化碳和水。例如，甲烷在氧气中燃烧：CH₄ + 2O₂ → CO₂ + 2H₂O。在氧气供应不足时发生的不完全燃烧会产生一氧化碳或碳（炭黑），这可能非常危险。
Oxidation also occurs more slowly, such as when metals tarnish or food goes rancid. Understanding these processes links to both environmental chemistry and everyday safety.
氧化也可以缓慢发生，例如金属失去光泽或食物变质。理解这些过程与环境化学和日常安全息息相关。
9. Separation Techniques | 分离技术
Mixtures can be separated using physical methods that rely on differences in physical properties. Filtration separates an insoluble solid from a liquid, for example sand from water. Evaporation heats a solution to drive off the solvent, leaving the soluble solid behind.
混合物可以利用物理性质的差异通过物理方法进行分离。过滤用来分离不溶性固体和液体，例如从水中分离出沙子。蒸发是将溶液加热，使溶剂汽化，留下可溶性固体。
Chromatography is used to separate mixtures of dissolved substances, such as the colours in ink. A small spot of the mixture is placed on chromatography paper, and a solvent carries the different components at different speeds. Distillation separates a liquid from a solution based on boiling points: the liquid boils first, its vapour is cooled and collected as a distillate.
色谱法用于分离溶解的物质混合物，例如墨水中的颜色。将少量混合物点在层析纸上，溶剂会以不同速度带着各组分移动。蒸馏根据沸点的不同从溶液中分离液体：液体先沸腾，其蒸气被冷凝后收集为馏出液。
These techniques are not only practical skills but also help you understand the nature of mixtures and pure substances. Choosing the correct separation method depends on the properties of the components.
这些技术不仅是实验技能，还能帮助你理解混合物与纯净物的本质。选择正确的分离方法取决于组分的性质。
10. Earth’s Materials and Everyday Chemistry | 地球物质与日常化学
The Earth provides us with many important materials. The atmosphere is composed of about 78% nitrogen, 21% oxygen, and small amounts of carbon dioxide, argon, and water vapour. Rocks are classified into three main types: igneous (formed from cooled magma), sedimentary (formed from compressed sediments), and metamorphic (formed by heat and pressure changing existing rocks).
地球为我们提供了许多重要材料。大气约由 78% 的氮气、21% 的氧气以及少量的二氧化碳、氩气和水蒸气组成。岩石分为三大类：火成岩（由冷却的岩浆形成）、沉积岩（由压实的沉积物形成）和变质岩（由热和压力改变原有岩石形成）。
The rock cycle shows how rocks change from one type to another over millions of years. Weathering and erosion break down rocks, transporting sediments to form new rocks. Limestone, a sedimentary rock, reacts with acid rain because it contains calcium carbonate (CaCO₃), reminding us how chemistry affects our environment.
岩石循环展示了岩石在数百万年间如何从一种类型转变为另一种。风化与侵蚀使岩石分解，搬运沉积物形成新的岩石。石灰岩是一种沉积岩，由于含有碳酸钙 (CaCO₃)，会与酸雨反应，这提醒我们化学是如何影响环境的。
In Year 8, linking chemical ideas to real-world contexts—such as the carbon cycle, the extraction of metals from ores, and the use of natural resources—deepens your understanding of why chemistry is an essential science for everyday life and the planet's future.
在八年级，将化学概念与现实情境联系起来——例如碳循环、从矿石中提取金属以及自然资源的使用——能够加深你对化学为什么是日常生活和地球未来必不可少的一门科学的理解。
Published by TutorHao | Chemistry Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图