JR2 Chemistry Notes

Chapter 1 : Atoms(原子）、Molecules(分子）and Ions(离子）

● Atoms （原子）
● Molecules（分子）
● Ions (离子）

Element is a pure substance that cannot be split into 2 or more simpler
substances by chemical processes
元素是一种纯物质，不能通过化学过程分解为2种或更多种更简单的物质

Atoms（原子）
Atoms is the smallest particle of an element that takes part in a chemical
reaction
在化学过程中，原子是元素中最小的粒子

Dalton's Atomic Theory 道耳顿原子论
➔ All substances are made of atoms. Atoms are the smallest particles in
matter and they cannot be divided into smaller particles. They also
cannot be created or destroyed
➔ All atoms of the same element are alike and have the same mass.
Atoms of different elements are different and have different masses
➔ Atoms of different elements combine in fixed ratios to form
compounds. The formation of compounds results from the
rearrangement of existing atoms.

➔ 所有的东西都是由原子组成。原子是物质中最小的粒子，不能再分成更
小的粒子。它们也不能被创建或销毁

➔ 同一元素的所有原子都相似，质量相同。不同元素的原子不同，质量也
不同

➔ 不同元素的原子以固定比例结合形成化合物。化合物的形成源于现有
原子的重排

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Symbols for the elements（元素符号）

1 Hydrogen 氢 H 11 Sodium 钠 Na

2 Helium 氦 He 12 Magnesium 镁 Mg

3 Lithium 锂 Li 13 Aluminium 铝 Al

4 Beryllium 铍 Be 14 Silicon 硅 Si

5 Boron 硼 B 15 Phosphorus 磷 P

6 Carbon 碳 C 16 Sulphur 硫S

7 Nitrogen 氮 N 17 Chlorine 氯 Cl

8 Oxygen 氧 O 18 Argon 氩 Ar

9 Fluorine 氟 F 19 Potassium 钾K

10 Neon 氖 Ne 20 Calcium 钙 Ca

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● The elements are arranged in 7 horizontal rows. The rows are called periods（周
期）and they are numbered from 1 to 7

● The vertical columns of the periodic table are called groups（族）. Each group is
further subdivided into sub-groups A and B. They are numbered from 1 to 18

● The elements in the same group have similar chemical properties（化学性质）
● Elements are arranged in order of increasing atomic number（原子序数）

● 元素排列成 7 个行。这些行称为周期，从 1 排 到 7（元素周期表左从上往下）
● 元素周期表的垂直列称为族群。每组进一步细分为子组 A 和 B。它们的从 1 排到 18

（元素周期表上从左到右）
● 同族元素具有相似的化学性质
● 元素按原子序数增加的顺序排列

Groups of the Periodic Table

➔ Group 1（IA族）
◆ These elements are known as alkali metals（碱金属）.They are
soft and can be easily cut
◆ Are very reactive metals（活泼金属）. They react violently with
water to produce alkaline solution and hydrogen gas.
◆ Must be kept in paraffin oil（石蜡油）to avoid explosion.

➔ Group 2 （IIA族）
◆ Known as alkaline metals（碱土金属）

➔ Group 17（VIIA族）
◆ Are known as halogens（卤素）
◆ All halogens are poisonous and their colours become darker
going down the group
◆ Are reactive non-metal（活泼非金属）

➔ Group 18（VIIIA族）
◆ Are known as noble gases or rare gases（稀有气体）
◆ Are chemically unreactive（不活泼）

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1.2 Structure of atom : Proton（质子）、Electron（电子） and
Neutron（中子）

What are atoms made up of?

Atoms are made up of:
● Proton（质子）
● Electron（电子）
● Neutron（中子）

Protons and neutrons are tightly packed together, they form the nucleus（原子核） of an
atom
Electrons move rapidly around nucleus

Proton Number and Nucleon Number

All atoms are electrically neutral（中性）. An atom contains an equal number of protons
and electrons.
The number of protons and in an atom is called proton number（质子数）or the atomic
number（原子序数）

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Nucleon Number

Nucleon number can also be called the mass number

Nucleon Number = number of protons + number of neutrons

1.3 Molecules（分子）

Molecule is a group of 2 or more atoms that are chemically bonded together
分子是由 2 个或更多原子化学键合在一起的组

➔ Atoms such as hydrogen, oxygen, nitrogen, fluorine, chlorine, bromine and iodine
are join in pairs, are known as diatomic molecules

➔ Molecules that are form by combination of 4 or more atoms are called polyatomic
molecules

Molecules are not always formed by atoms of the same element joining together For ex:
➔ Water molecules（水分子）consist of oxygen and hydrogen atoms chemichally
bonded, H2O
➔ Ethanol molecule（酒精分子）consists of carbon, hydrogen and oxygen chemically
bonded, C2H5OH

Water is not an element itself. It is a compound made from 2 types of elements (
hydrogen and oxygen) and it can be broken down by electrolysis（电解法）

Electrolysis is a process of breaking down a compound to its constituent
elements by running electric current through it

电解是通过电流通过化合物将化合物分解为其组成元素的过程

Molecules are the smallest particles that give the chemical properties of water
分子是保持物质化学性质的最小的粒子

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1.4 Ions（离子）

Other than atoms and molecules, matter can also be made up of ions（离子）
Table salt- Sodium Chloride（NaCl，氯化钠）is made of sodium ions and chloride ions
食用盐- 氯化钠（NaCl）是由钠离子和氢离子组成

Formation of Ions 离子的形成

Atoms are electrically neutral because they have equal number of protons and electrons
An atom becomes an ion when it loses or gains electrons. An ion is a charged particle.
原子是电中性的，因为它们具有相同数量的质子和电子
当原子失去或得到电子的时候会形成离子，离子是带电子的
An ion is charged particle formed from atom or a group

of atoms by the loss or gain of electron
离子是由原子或一组原子形成的带电粒子原子因失去或获得

电子
1. Atoms of metals tend to lose electrons to form positively charged ions (cation)

金属原子倾向于失去电子形成带正电的离子（正离子）
2. Atoms of non-metal tend to gain electrons to form negatively charged ions

(anion) 非金属原子倾向于获得电子形成带负电的离子（负离子）

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Formation of sodium chloride

When sodium metal burns in chlorine gas, sodium atoms lose electrons and become
positive ions-sodium ions, while chlorine atoms gain electrons to become negative
ions-chloride ions.
钠金属在氯气中燃烧时，钠原子失去电子成为正离子-钠离子，而氯原子获得电子成为负离
子-氯离子

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Chapter 2 : Compounds（化合物） and mixtures（混合物）

2.1 Compounds（化合物）

A compound is a substance that contains atoms of 2 or more different elements
that are chemically combined

化合物是一种物质，它包含两种或多种不同元素的原子，这些元素以化学方式结合在一起

➔ Water is a compound of hydrogen and oxygen. Each of its molecules contains 2
hydrogen atoms and 1 oxygen atom

➔ Sodium is a shiny metal. Chlorine is a green, smelly and poisonous gas at 20°C. When
these 2 elements join together, it makes a compound called sodium chloride,NaCl

➔ When elements form compounds they no longer display their own special properties.
They form their own special properties as a compound.

➔ 水是氢和氧的化合物。每个水分子含有2个氢原子和1个氧原子
➔ 钠是一种有光泽的金属。氯在 20°C 时是一种绿色、有臭味和有毒的气体。当这两种

元素结合在一起时，就会形成一种叫做氯化钠的化合物，NaCl
➔ 当元素形成化合物时，它们不再显示自己的特殊属性。它们以化合物的形式形成自

己的特殊属性。

2.2 Common compound on Earth

Naming compounds
● Compounds of a metal and non-metal（金属，非金属的化合物）
● Compounds of a metal, a nonmetal and oxygen （金属，非金属和氧气
的化合物）
● Compounds containing nonmetals only （非金属化合物）

➔ Compounds of a metal, nonmetal and oxygen

◆ Write the name of metal
◆ Write name of nonmetal, but change the end to ide

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Metal Non-metal Name of compound
Zinc oxygen Zinc oxide
sodium chlorine
calcium sulphur Sodium chloride
Calcium sulphide

金属 非金属 化合物名字 化学式
锌 氧 氧化锌 ZnO
钠 氯 氯化钠 NaCl
钙 硫 硫化钙 CaS

➔ Compounds of a metal, a nonmetal and oxygen

◆ Write the name of metal
◆ Write name of non-metal, bur change the end to ate (shows compound

contains oxygen)

Elements in the compounds Name of compound
Copper, sulphur, oxygen Copper(II) sulphate
Potassium nitrate
Potassium, nitrogen, oxygen Magnesium carbonate
Magnesium, carbon, oxygen

化合物的元素 化合物名称 化学式
铜，硫，氧 硫酸铜 CuSO4
钾，氮，氧 硝酸钾 KNO3
镁，碳，氧 碳酸镁 MgCO3

➔ Compounds containing nonmetals only

◆ Know the numbers of atoms of each element in a molecule of compound
◆ Example: 1 carbon atom and 1 oxygen atom is carbon monoxide

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Number of atom in compounds Name of compound
1 atom of sulphur and 2 atom of oxygen Sulphur dioxide
1 atom of sulphur and 3 atoms of oxygen Sulphur trioxide
1 atom of phosphorus and 3 atoms of chlorine
2 atoms of nitrogen and 4 atoms of oxygen Phosphorus trichloride
Dinitrogen tetroxide
化合物中的原子数量 化合物名称
1个硫原子和2个氧原子 二氧化硫 化学式
1个硫原子和3个氧原子 三氧化硫 SO2
1个磷原子和3个氯原子 三氯化磷 SO4
2个氮原子和4个氧原子 四氧化二氮 POCl3
N2O4

Oxides（氧化物）

➔ An oxide is a compound made up of oxygen and another element
◆ Heating elements in the air will form oxides
◆ Examples: magnesium oxide, sulphur dioxide

➔ Many oxides exist naturally in the Earth's crust
◆ Sand is silicon dioxide
◆ Rubies consist aluminium oxide with tiny amount of chromium

➔ Metal oxides and nonmetal oxides have different properties
➔ Most nonmetal oxides（非金属氧化物）are acidic

◆ When carbon dioxide is bubbled into pure water, it forms a solution that
has a pH less than 7

◆ Examples: nitrogen dioxide, sulphur dioxide
➔ Metal oxides（金属氧化物）are bases（碱）.This means they neutralise acids

◆ Some metals dissolve in water to form alkaline solutions. Ex: Sodium
oxide

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氧化物

➔ 氧化物是由氧气和其他元素组成
◆ 在空气中加热元素会产生氧化物，如：氧化镁，氧化硫

➔ 地球的地壳上存在许多天然氧化物
◆ 沙是氧化硅

➔ 金属氧化物和非金属氧化物有不同的性质
➔ 大部分非金属氧化物都是酸性的

◆ 当二氧化碳和水产生反应时，会形成一个pH低于7 的溶液
◆ 列子：二氧化氮，二氧化硫
➔ 金属氧化物是碱性物质，可以用于中和酸性物质
◆ 一些金属与水反应后会形成碱性溶液，如：氧化纳

Hydroxide（氢氧化物）

➔ A hydroxide is a compound made up of a metal, oxygen and hydrogen
◆ Sodium hydroxide contains atoms of sodium, oxygen and hydrogen
◆ Potassium hydroxide contains atoms of potassium, oxygen and hydrogen

➔ Some metal hydroxides dissolve in water to form alkaline solution,
◆ examples : sodium hydroxide and potassium hydroxide

氢氧化物

➔ 氢氧化物是由金属，氧气和氢气组成
◆ 氢氧化钠是由钠，氧和氢原子组成
◆ 氢氧化钾是由钾，氧和氢原子组成

➔ 金属氢氧化物与水产生反应后会形成碱性溶液
◆ 如：氢氧化钠，氢氧化钾

Sulphates（硫酸盐）

➔ A sulphate is a compound made up of a metal, sulphur and oxygen
◆ Example: copper(ii) sulphate which exists as blue crystals

硫酸盐

➔ 硫酸盐是由金属，硫和氧组成
◆ 如：硫酸铜（ii)

Carbonates（碳酸盐）

➔ A carbonate is a compound made up of a metal, carbon and oxygen
➔ Calcium carbonate, CaCO3, exists naturally as limestone and marble. It is used

as building material

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碳酸盐

➔ 碳酸盐是由金属，碳和氧气组成
➔ 碳酸钙，CaCO3，存在于大理石和石灰石中

Summary

Characteristics of compound:
➔ Formed by 2 or more elements that are combined chemically
➔ Produced through a chemical reaction
➔ Consist of different elements
➔ Components cannot be separated physically

总结

化合物特征：
➔ 由2个或更多的元素化合组成
➔ 由化学反应组成
➔ 有不同的元素
➔ 不能被具体的拆散

2.3 Mixtures（混合物）

A mixture is formed by 2 or more elements or compounds that combined
physically 混合物由2种或多种元素或化合物物理结合而成

Mixtures can contain elements, compounds or both
➔ When you mix iron and sulphur together, you are making a mixture of 2 elements
➔ Ingredients in toothpaste are mixtures of compounds
➔ Air is a mixture of substances. It contains elements such as nitrogen, oxygen and
argon

Mixtures are not pure. It is made up by kinds of particles that are mixed together
混合物是不纯的，它是由各种粒子混合在一起

Formation of mixtures（混合物的形成）

Mixtures can be formed by mixing elements together

➔ Mixture of metals is called alloy（合金）
➔ Alloy : when 2 or more metals are melted together / a metal and non-metal

melted together to form a substance which has metallic properties

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➔ Example: bronze（青铜）is an alloy made by mixing copper and tin. It is harder
than either copper or tin

Mixtures can also be formed by mixing elements and compounds

➔ The atmosphere air contains a mixture of gases which are elements and
compounds

Mixtures can also be formed by mixing compounds and compounds

➔ Mineral water is a mixture. The minerals are dissolved in the water. The water is
a solution

What is the difference between mixtures and compounds?

Mixtures differences compounds
Way of formation
Formed by physical Formed by chemical
methods no chemical Formation of new reactions
substances
reaction involved Properties A new substance is formed

No new substances are Ratio of composition Properties of a compound
formed are different from those of
Change of energy elements in the compound
Properties are the same as Separation method
those of its components The composition is fixed
because the components
The composition varies combine at a fixed ratio
because the components
can combine at any ratios Absorption or release of
heat may occur
No absorption or release of
heat Can be separated by
chemical method only,such
Can be separated by
physical methods, for as electrolysis
examples using magnetic
attraction or filtration

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混合物和化合物有什么区别？

混合物 区别 化合物
由物理方法形成，不涉及化 形成方式 由化学反应形成

学反应 新物质的形成 一种新物质形成
性质
没有新物质形成 化合物的性质与化合物里的
化学成分的比例 元素不一样
性质与其成分一样 成分是固定的，因为成分以
能量转换
成分不同，因为成分可以以 分离方法 固定的比例结合
任何比例组合
可能会吸热或放热
不吸收或释放热量 只能通过化学方法分离，例
可以通过物理方法分离，例
如电解法
如使用磁力吸引或过滤

2.4 Separating mixtures

➔ Decanting（倾析法)

◆ Use to separate mixture of solid
and liquid, can also separate
liquids with different densities

◆ 用于分离固液混合物，也可分离不

同密度的液体

➔ Filtering（过滤法）

◆ Use to separate insoluble solid from
liquid

◆ 从液体分离不可溶解的固体

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➔ Evaporation（蒸发）

◆ Use to separate a soluble
solid from a liquid

◆ 用于从液体中分离可溶性固
体

➔ Distillation（蒸馏法）

◆ Simple distillation
● Use to separate solvent from a solution

◆ Fractional distillation
● Is use to separate a liquid from a mixture of 2
or more liquids
● This method works because liquids in the
mixture have different boiling points
● 用于从两种或多种液体的混合物中分离出一种
液体
● 这种方法有效是因为混合物中的液体具有不同
的沸点

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Chapter 3 : Chemical Formulae of Compounds

3.6 Chemical formulae（化学式）

1. A chemical formula is a representation of a chemical substance using symbols of
elements (元素符号）and subscript numbers（下表数字）to show the numbers of
each type of atoms that are present in the substance.

2. Based on the chemical formula of a substance, we know the composition of the
substance.
a) The elements that make up the substance
b) The ratio or number of atoms of each element in the substance

For example: The chemical formula of sulphuric acid（硫酸）is H2SO4.
a) A molecule of sulphuric acid contains three elements: hydrogen, sulphur and
oxygen.
b) The atoms are in the ratio of 2 hydrogen atoms : 1 sulphur atom : 4 oxygen
atoms.

1. 化学式是一种化学物质的表示，是用元素符号和下标数字来显示物质中存在的每种

类型原子的数量
2. 根据物质的化学式，我们知道该物质的成分

a. 构成物质的元素
b. 物质中每种元素的原子数或比例

硫酸的化学式是 H2SO4 所以我们可以得知：
1. 1个硫酸分子含有三种元素：氢、硫和氧
2. 原子的比例为2个氢原子：1个硫原子：4个氧原子

Chemical formulae of element（单质的化学）

Element Chemical Meaning of chemical formula
formula

Copper（铜） Cu Copper is made up of copper atoms

Carbon（碳） C Carbon is made up of carbon atoms

Argon（氩） Ar Argon is made up of argon atoms

Oxygen gas（氧气） O2 Each oxygen molecule consists of two oxygen atoms

Chlorine gas（氯） Cl2 Each chlorine molecule consists of two chlorine atoms

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元素 化学式 化学式的含义
铜 Cu 铜是由铜原子组成的
碳 C 碳是由碳原子组成的
氩 Ar 氩气由氩原子组成
氧气 O2 每个氧分子由两个氧原子组成
氯气 Cl2 每个氯分子由两个氯原子组成

Chemical formulae of compounds

1. Chemical formula of a compound tells us the
composition of compound

2. The number ‘1’ is not written in a chemical formula.
Thus, H2O1 is written H2O

1. 化合物的化学式告诉我们化合物的组成
2. 数字“1”没有写在化学式中。因此，H2O1 写成 H2O

Compound Chemical formula Meaning of chemical formula
化合物 化学式
Elements present Ratio of the number of
atoms of elements

water H2O hydrogen, oxygen H:O = 2:1
NH3
Ammonia（氨气） HCl nitrogen, hydrogen N:H = 1:3

Hydrochloric acid Zn(OH)2 Hydrogen, chlorine H:Cl = 1:1
（盐酸）
Mg(NO3)2 Zinc, oxygen, Zn:O:H = 1:2:2
Zinc hydroxide（氢 hydrogen Mg:N:O = 1:2:6
氧化锌）
Magnesium,
Magnesium nitrate nitrogen, oxygen
（硝酸镁）

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3.2 Valency（化合价）

1. Valency of an element is a measure of its combining power with other atoms
when it forms chemical compounds

2. The valency of metals is assigned a positive charge. This is because metals lose
electrons during reaction to form positive ions (cation)

3. The valency of non-metals are assigned a negative charge because they gain
electrons during reactions to form negative ions (anions)

4. Transition metals like copper and iron have more than 1 valency. Iron forms
iron(ii) ions and iron(iii) ions, while copper forms copper(i) and copper(ii) ions

5. We use valency of an element to construct the chemical formulae of compounds
1. 元素的化合价是衡量它与其他原子形成化合物时的结合能力
2. 金属的化合价被赋予一个正电荷。这是因为金属在反应过程中失去电子形成正离子

（正离子）
3. 非金属的化合价被赋予负电荷，因为它们在反应过程中获得电子以形成负离子（负

离子）
4. 铜和铁等过渡金属的价数超过 1。铁形成铁（ii）离子和铁（iii）离子，而铜形成铜（i）和

铜（ii）离子
5. 我们使用元素的化合价来构建化合物的化学式

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The valency and formulae of some common positive ions

Positive ions（正离子）

Valency（化合价） Metal ions 金属离子 Formulae of ions

Sodium ion 钠离子 Na+

Potassium ion 钾离子 K+
Ag+
+1 Silver ion 银离子

Hydrogen ion 氢离子 H+

Ammonium ion *铵根离子 NH4 +

Magnesium ion 镁离子 Mg2+

Calcium ion 钙离子 Ca2+

Barium ion 钡离子 Ca2+
Zn2+
+2 Zinc ion 锌离子

lead(ii) ion 铅离子 Pb2+

iron(ii) ion 铁（II）离子 Fe2+

copper(ii) ion 铜（II）离子 Cu2+

Aluminium ion 铝离子 Al3+

+3 iron(iii) ion 铁（III）离子 Fe3+

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The valency and formulae of some common negative ions

Negative ions（负离子）

Valency（化合价） Non-metal ions 非金属离子 Formulae of ion

Fluoride ion 氟离子 F-

Chloride ion 氯离子 Cl-

Bromine ion 溴离子 Br-
I-
-1 Iodide ion 碘离子

Hydroxide ion 氢氧根离子 OH-

Nitrate ion 硝酸根离子 NO3 -

Chlorate ion 氯酸根离子 ClO3 -

Oxide ion 氧离子 O2-

Sulphide ion 硫离子 S2-

-2 Carbonate ion 碳酸根离子 CO3 2-

Sulphate ion 硫酸根离子 SO4 2-

-3 Phosphate ion 磷酸根离子 PO4 3-

Writing chemical formulae

Rules:
1. Compound consists of positive ion and negative ions
2. Positive charges of the cation have to be balanced by the negative charges of
the anion
3. Total charge of a compound must be zero

1. 化合物由正离子和负离子组成
2. 正离子的正电荷必须被负离子的负电荷平衡
3. 化合物必须是0电荷

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Calcium Chloride
Ca2+ Cl-
+2 -1
1 2

CaCl2

1. Write the formulae of cation on the left and anion on the right
2. Determine the valency for each cation and anion
3. Interchange & simplify
4. Write down formula

1. 把正离子写在左边，负离子写在右边
2. 知道正离子和负离子的化合价
3. 互换和简化
4. 把化学式写下来

Examples:

Magnesium Oxide

Mg2+ O2-

+2 -2

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MgO

Aluminium nitrate

Zn2+ NO3 -

+3 -1

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Zn(NO3)3

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3.3 Relative mass of atoms and molecule

Relative Atomic Mass R.A.M （相对原子质量）

Relative Molecule Mass R.M.M（相对分子质量）

1. Relative molecular mass of a molecule is defined as the average mass of a
molecule of the substances when compared with one twelfth of the mass of 1
carbon 12 atom

2. Relative molecular mass of a molecule is calculated by adding up the relative
atomic mass of all the atoms

1. 分子的相对分子质量定义为物质分子的平均质量与 1 个碳 12 原子质量的十二分之
一相比

2. 通过将所有原子的相对原子质量相加来计算分子的相对分子质量

Substances Chemical Formula Relative Molecular mass
Hydrogen gas H2 2(1) = 2
Oxygen gas O2
H2O 2(16) = 32
Water NaBr 2(1) + 16 =18
Sodium bromide 23 + 80 = 103

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Chapter 4 : Chemical Reaction And Chemical Equations
4.1 Physical and Chemical changes（物理和化学变质）

Physical changes Chemical changes

Physical properties such as colour, The chemical composition and
physical state, volume, etc. change. chemical properties change.
Chemical properties remain
unchanged.

No new substance is formed. A new substance is formed

Temporary change Permanent change

Reversible Irreversible

Very little or no energy changes is Usually involves absorption or

involved release of energy.

物理变质 化学变质

诸如颜色、物理状态、体积等的物 化学成分和化学性质发生变化。
理属性会发生变化。化学性质保持
不变。

没有新物质形成。 有新物质形成

暂时性改变 永久性改变
可逆的 不可逆的
很少或不涉及能量变化 通常涉及能量的吸收或释放。

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4.2 Chemical Reaction（化学反应）

➔ Are processes by which chemicals interact to form new chemicals with different
compositions.

➔ Creates new substances and process are not reversible

➔ 是化学物质相互作用形成具有不同成分的新化学物质的过程
➔ 创造新的物质和过程是不可逆的

How can we recognise a chemical reaction（我们要如何分辨化学反应）

1. Temperature change 温度变化
2. Light 光
3. Precipitate formation 沉淀物
4. Colour change 颜色的变化
5. Odour change 气味的变化

4.4 Law of conservation of mass and chemical equations

Law of conservation of mass（质量守恒定律）

● The total mass of the products will remain equal to the total mass of the reactants
in a chemical reaction.

● The law of conservation of mass is used to balance the chemical equations
where the number and type of atoms must be the same for both reactants and
products.

● 在化学反应中，产物的总质量将保持等于反
应物的总质量。

● 质量守恒定律用于平衡化学方程式，其中反
应物和产物的原子数量和类型必须相同。

Types of chemical reaction

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● Combination Reaction（化合反应）
● Decomposition Reaction（分解反应）
● Displacement Reaction（置换反应）
● Double Decomposition Reaction（复分解反应）

Combination reaction （化合反应）

A + B → AB

Chemical reaction Examples
化学反应 列子

Metal + Oxygen → Metal Oxide 2Mg + O2 → 2MgO 镁 + 氧 → 氧化镁
金属 + 氧 → 氧化金属 4Na + O2 → 2Na2O 钠 + 氧 → 氧化纳

Non metal + Oxygen → Non-metal oxide S + O2 → SO2
非金属 + 氧 → 氧化非金属 C + O2 → CO2

Metal oxide + Water → Alkali Na2O + H2O → SO2
氧化金属 +水 → 碱
CO2 + H2O → H2CO3
Non-metal oxide + Water → Acid SO2 + H2O → H2SO3
氧化非金属 + 水 → 酸

Decomposition reaction（分解反应）

AB → A + B

Chemical reaction 化学反应 Example 列子

Metal carbonate → metal oxide + carbon dioxide CaCO3 → CaO + CO2

金属碳酸盐 → 氧化金属 + 二氧化碳 CuCO3 → CuO + CO2

Metal bicarbonate → metal carbonate + water + Ca(HCO3)2 → CaCO3 + H2O +
carbon dioxide CO2
金属碳酸氢盐 → 金属碳酸盐 + 水 + 二氧化碳

Displacement reaction（置换反应）

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A + BC → AC + B

Reaction of metals with acid

Metal + acid → salt + hydrogen
金属 + 酸 → 盐 + 氢

Reaction of metals with water

Reactive metal + water → alkali + hydrogen
活泼金属 + 水 → 碱 + 氢

Reaction of metals with steam

Metal + steam → metal oxide + hydrogen
金属 + 水蒸气 → 氧化金属 + 氢

Reaction of metals with salt solutions

Metal A + Salt B → Salt A + Metal B
金属A + 盐B → 盐A + 金属B
Cu + 2AgNO3 → Cu(NO3)2 + 2Ag

Double decomposition reaction（复分解反应）

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AB + CD → AD + BC

Precipitate reaction

Example: AgNO3 + NaCl → NaNO3 + AgCl
AgCl is precipitate

Neutralization reaction

Neutralization between acid and base Forms salt and water
● Acid + alkaline → salt + water
● Basic oxide + acid → salt + water
● Acidic oxide + alkali → salt + water

Neutralization Between acid and metal carbonate forms salt, carbon dioxide and water
● Metal carbonate + acid → salt + water + carbon dioxide

4.6 Energy changes in chemical reaction

Characteristics of endothermic and exothermic reactions

Endothermic 吸热反应 Exothermic 放热反应

Heat energy is absorbed and transferred Heat is released from the reactants and
from the surroundings to the reactants transferred to the surroundings
热能被吸收并从周围转移到反应物 反应物释放热量并传递到周围环境

The temperature of the reaction mixture The temperature of the reaction mixture
falls. Container feels cooler rises. Container feels warmer

反应物的温度下降。容器变冷 反应物的温度上升。容器变热

Chapter 5 : atmosphere and composition of air

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5.2 characteristic of the atmosphere

Atmospheric layer Physical properties Characteristic
大气层 物理特性 特征

Troposphere 对流层 Altitude: 0-10km ● Closest to earth
Air pressure: 100-1000mb ● Complicated weather
Temperature: -52°C to 17°C
conditions
Stratosphere 平流 Altitude: 10-50km ● Densest layer, has highest
层 Air pressure: 1-100 mb
Temperature: -25°C - -3°C air pressure

Mesosphere 中间层 Altitude: 50-85km ● Temperature rises with
Air Pressure: -1 to 0.01mb height
Temperature: -93°C - -3°C
● Has no clouds, dust nor
Thermosphere 热层 Altitude: 85-500km water vapour
Air pressure: very low
Temperature: -93°C - -3°C ● Suitable for commercial
plane flight
Exosphere 散逸层 Altitude: 500-800km
Air pressure: exactly low ● Has the ozone layer
Temperature: 270°C - 1100°C
● The temperature decrease
with increasing height

● Coldest layer
● Density is small
● Protects earth from

meteoroids

● Hottest layer
● Temperature increases

rapidly high
● Auroras are formed in this

layer

● Outermost layer of the
earth’s atmosphere

● Lowest density and air
pressure

● Contains hydrogen and
helium gas[

5.3 The composition of air

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● 78% nitrogen, N2 氮
● 21% oxygen, O2 氧
● 0.9% argon, Ar 氩
The importance of air to living things

The earth is surrounded by air, such as oxygen, carbon dioxide and nitrogen.these
gases provide humans and animals with oxygen for respiration to occur. It also provides
green plants with carbon dioxide for photosynthesis to happen. It is vital that living
things respire to get the oxygen for living cells to function. Without air, there’s no life

地球被空气包围，如氧气、二氧化碳和氮气。这些气体为人类和动物提供氧气以进行呼吸。
它还为绿色植物提供二氧化碳以进行光合作用。生物通过呼吸来获取氧气以供活细胞发挥
作用至关重要。没有空气就没有生命

5.4 Air pollution
Sources of air pollution

sources pollutions

Exhaust of vehicles and factories Smoke, soot, dust, carbon monoxide,
车辆和工厂的尾气 sulphur dioxide, nitrogen dioxide, lead

烟雾、煤烟、灰尘、一氧化碳、二氧化硫、二
氧化氮、铅

Nuclear power station 核电站 Radioactive waves 辐射

Agriculture and farming activities Residue of pesticides, chemical fertiliser
农业活动 农药和化肥残留

Decomposed organic matter and Methane, carbon dioxide and hydrogen

plants waste 分解的有机物和植物废物 sulphide 甲烷、二氧化碳和硫化氢

Construction side, asbestos factories, Dust, soot, asbestos
limestone quarries

Air conditioners, refrigerator, aerosol chlorofluorocarbon
sprays, electronic factories

Open burning, forest fires, cigarette Smoke, dust, soot, metallic particles
smoke

Burning of fossil fuel in factories and Carbon dioxide, nitrogen dioxide, sulphur
power station dioxide

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Volcanic eruptions Carbon dioxide, carbon monoxide, sulphur
dioxide

5.5 the importance of ozone layer（臭氧层）

Ozone layer is a part of the stratosphere that contains most of the ozone. It serves as a
protective shield for the earth. Ozone absorbs a large amount of ultraviolet light from the
sunlight, hence the organisms on earth will not be harmed by UV radiation. However,
the ozone layer has been depleting due to human activities.

臭氧层是包含大部分臭氧的平流层的一部分。它充当地球的保护屏障。臭氧从太阳光中吸
收大量紫外线，因此地球上的生物不会受到紫外线辐射的伤害。然而，由于人类活动，臭氧
层一直在消耗。

Chapter 6 : Gases

6.1 Nitrogen（氮气）
Characteristics and properties of nitrogen gas

Nitrogen is a diatomic molecule, each molecule containing two nitrogen atoms. Nitrogen
is colourless is a colourless, tasteless, odourless gas that is slightly soluble in water. It is
slightly less dense than air. Nitrogen has a low melting and boiling point (-196°C）and
exists as gas at room temperature.

Nitrogen gas is unreactive, it is non-flammable and does not support combustion, but
when heated to very high temperature, it combines with some of the more reactive
metals, such as magnesium to form nitrides（氮化物）.

氮是双原子分子，每个分子含有两个氮原子。氮气是一种无色、无味、无臭的气体，微溶于
水。它的密度略小于空气。氮气的熔点和沸点较低（-196°C），常温下以气体形式存在。

氮气不活泼，不易燃，不助燃，但加热到很高的温度时，它与一些较活泼的金属，如镁结合
形成氮化物

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Magnesium + nitrogen → magnesium nitride
镁 + 氮 → 氮化镁

The primary industrial use of nitrogen is to make ammonia（氨气）where nitrogen and
hydrogen combine in the presence of catalyst to produce ammonia, NH3 in a method
known as Haber process. Ammonia is then used to make fertilizers, nitric acid and
explosives.
氮气的主要工业用途是制造氨气，其中氮气和氢气在催化剂的存在下以一种称为 Haber 工
艺的方法生成氨，即 NH3。氨然后用于制造肥料、硝酸和炸药。

Nitrogen + hydrogen → ammonia
氮+氢→氨

6.2 Noble gases

Characteristic and properties of noble gases

Noble gases are also known as rare gases or the inert gases. They are monoatomic
gas（单原子气体）. They are called noble gases because they are all chemically
unreactive.
稀有气体也称为稀有气体或惰性气体。它们是单原子气体。它们被称为惰性气体，因为它们
都没有化学反应

6.3 Oxygen

Characteristics and properties of oxygen

Oxygen is found naturally as diatomic molecules, it has a low melting point and boiling
point. Oxygen gas is colourless, odourless and tasteless. It is more dense than air. Solid
and liquid oxygen are pale blue.

Oxygen is slightly soluble in water. Oxygen is a very reactive element. It reacts with
many elements to form oxides.

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氧气是天然存在的双原子分子，它具有低熔点和沸点。氧气无色、无臭、无味。它比空气更
密集。固态和液态氧呈淡蓝色。

氧气微溶于水。氧气是一种非常活泼的元素。它与许多元素反应形成氧化物

Preparation of oxygen gas in laboratory
1. By heating method

When potassium chlorate is heated in the
presence of manganese(IV) oxide, it
decomposes into potassium chloride and
oxygen gas
氯酸钾在氧化锰（IV）存在下加热时，分解为氯
化钾和氧气
Oxygen gas is collected in a gas jar through the
downward displacement of water（排水集气法）

2. Without heating method

Oxygen can be also made from hydrogen
peroxide（过氧化氢/双氧水）which decomposes
slowly to form water and oxygen

How to test the presence of oxygen?

Oxygen supports combustion so a good method of testing oxygen is to take a glowing
wooden splint and place it in a test tube containing the sample of gas, it will rekindle of if
the gas is oxygen
氧气支持燃烧，因此测试氧气的一个好方法是将余烬的木支放在装有气体样本的试管中，
如果气体是氧气，它会复燃

Collecting gases

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Downward displacement of Downward delivery Upward delivery
water 排水集气法 向上排气法 向下排气法

This method is used for This method is used for This method is used for
gases which are insoluble gases which are soluble in gases which are soluble in
or slightly soluble in water water but less dense than
该方法用于不溶于水或微溶 water but dense in air air 此方法适用于可溶于水
此方法适用于可溶于水但在
于水的气体 但密度小于空气的气体
空气中密度大的气体

6.4 Carbon dioxide

Reaction of carbon dioxide with water

→H2O + CO2 H2CO3

Reaction of carbon dioxide with limewater

→Ca(OH)2 (s) + CO2 (g) CaCO3 (s) + H2O (l)

Test the presence of carbon dioxide gas

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Carbon dioxide turns limewater milky. A lighted wooden splint extinguishes in a test tube
of carbon dioxide but this happens with other gases too. So the limewater test is a
better choice. 二氧化碳使石灰水变成乳白色。点燃的木夹板在二氧化碳试管中熄灭，但其
他气体也会发生这种情况。所以石灰水测试是更好的选择。

➔ When carbon dioxide is bubbled through limewater, the limewater turns from
colourless to milky. A white
precipitate of calcium carbonate is
formed and this makes the
limewater cloudy and chalky

➔ 当二氧化碳在石灰水中鼓泡时，石灰
水从无色变为乳白色。形成白色碳酸
钙沉淀，这使得石灰水混浊和白垩

Preparation of carbon dioxide in laboratory

limestone reacts with hydrochloric acid to release bubbies of carbon dioxide gas.
Carbon dioxide is produced whenever an acid reacts with a carbonate. This makes
carbon dioxide easy to make in the laboratory
石灰石与盐酸反应释放二氧化碳气体气泡。每当酸与碳酸盐反应时就会产生二氧化碳。这
使得在实验室中很容易制造二氧化碳

→CaCO3 (s) + 2 HCl (aq) H2O (l) + CO2 (g) + CaCl2 (aq)

Carbon dioxide is soluble in water and more dense than air, so it can be collected by
downward delivery-upward displacement of air（向下排空气法）. As the carbon dioxide
falls out of the delivery tube and into the gas jar, it pushes the less dense air out of the
top of the gas jar.
二氧化碳易溶于水，密度比空气大，因此可以通过向下排空气法进行收集。当二氧化碳从输
送管落入气罐时，它会将密度较低的空气从气罐顶部推出。

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6.5 combustion and extinguishment

What is combustion（燃烧）？

Combustion is the scientific word for burning. It is a chemical reaction that produces
heat and light. The products of a combustion reaction are called oxides

Fire triangle

● Oxygen
● Heat
● Fuel

Fire extinguisher

Chapter 7 : Water
7.1 importance of water to life

Water is fundamental to life on earth. In photosynthesis, water combines with carbon
dioxide to produce carbohydrates and oxygen
水是地球上生命的基础。在光合作用中，水与二氧化碳结合产生碳水化合物和氧气

6CO2 + 6H2O → C6H12O6 + 6O2

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Test presence of water

Compound Anhydrous copper(II) sulphate Anhydrous cobalt(III)
(无水硫酸铜) chloride
(无水氯化钴)
Initial colour White
Observation Blue
The colour of white powder turns blue
in the presence of water The colour of blue powder
白色粉末遇水变蓝 turns pink in the presence
of water
蓝色粉末遇水变成粉红色

7.3 water cycle（水循环）

Steps in water cycle

A. Evaporation（蒸发
B. Transpiration（蒸腾作用）
C. Condensation（凝聚）
D. Precipitation（降水）
E. Surface runoff（地表径流）
F. Infiltration and percolation

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7.4 Purification of water

Process Function

Coagulation ● Alum(明矾) coagulates suspended particles,
● Slaked lime(生石灰）neutralises the acidity of water

Sedimentation ● Allowing the suspended particles in water to settle (sink to
the bottom) and form sediment and can be removed under
the effect of gravity

Filtration ● Separates leaves, branches rubbish and others
● Removes remaining suspended particles, algae, bacteria

and some chemicals through sand filters

Disinfection Chlorination ● Chlorine kills harmful
microorganisms

Fluoridation ● To prevent tooth decay

7.5 hard water and soft water

Hard water Soft water
Less mineral content
High content of minerals like magnesium
and calcium Bubbly lather from soaps
No soap scum is formed. Soap is
Less foam and lather from soaps effective

Soap scum is formed-soap is not so
effective

Leaves spots on the washed dishes after Does not leave any spots on dishes after

they are dried they are dried

Hair washed feel dry and sticky Hair washed feel soft

Contains mineral good for health Less health benefit-not preferred as
drinking water

Example: Groundwater like deep wells Example: rainwater

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