📚 Year 9 Edexcel Chemistry: Unit Test Mock Paper Analysis | 九年级爱德思化学：单元测试模拟卷解析
This article provides a step-by-step walkthrough of a mock unit test for Year 9 Edexcel Chemistry. Each section focuses on a key topic from the syllabus, presenting sample questions, clear explanations, and bilingual insights. Use this guide to identify common pitfalls, sharpen your problem-solving skills, and build confidence for your actual assessment.
本文将对一份九年级爱德思化学单元测试模拟卷进行逐步解析。每个小节聚焦一个核心知识点，提供样题、清晰的解释和中英双语要点。通过本指南，你可以识别常见错误、提高解题能力，并为真正的测评建立信心。
1. Atomic Structure and Subatomic Particles | 原子结构与亚原子粒子
Mock Question 1: An atom of aluminium has 13 protons, 14 neutrons and 13 electrons. State its atomic number and mass number. Explain why the atom has no overall charge.
模拟题1: 一个铝原子有13个质子、14个中子和13个电子。写出它的原子序数和质量数，并解释为什么这个原子呈电中性。
m is neutral because the 13 positive charges from protons exactly balance the 13 negative charges from electrons. In any neutral atom, the number of electrons equals the number of protons.
原子序数由质子数决定，所以是13。质量数是质子数和中子数之和，即13 + 14 = 27。该原子呈电中性，因为来自质子的13个正电荷与来自电子的13个负电荷恰好抵消。在任何中性原子中，电子数等于质子数。
The table below summarises the properties of the three subatomic particles you must know for the exam.
下表总结了考试中必须掌握的三种亚原子粒子的性质。
| Particle / 粒子 | Relative charge / 相对电荷 | Relative mass / 相对质量 | Location / 位置 |
|---|---|---|---|
| Proton / 质子 | +1 | 1 | Nucleus / 原子核 |
| Neutron / 中子 | 0 | 1 | Nucleus / 原子核 |
| Electron / 电子 | -1 | 1/1836 (negligible / 忽略不计) | Shells / 电子层 |
Mock Question 2: A fluorine atom has 9 protons and 10 neutrons. It gains one electron to become a fluoride ion. Determine the number of protons, neutrons and electrons in the ion, and explain why its charge is 1-.
模拟题2: 一个氟原子有9个质子和10个中子，它得到一个电子后变成氟离子。请确定该离子的质子数、中子数和电子数，并解释为什么它的电荷是1-。
e a total positive charge of +9, while 10 electrons give a total negative charge of -10. The overall charge is (+9) + (-10) = -1, which is written as F⁻.
氟离子仍有9个质子和10个中子（得到电子不改变原子核）。它现在有9 + 1 = 10个电子。9个质子贡献+9正电荷，10个电子贡献-10负电荷，总电荷为(+9) + (-10) = -1，写作F⁻。
2. Electron Configuration and the Periodic Table | 电子排布与元素周期表
Mock Question 3: The electronic configuration of an atom is 2,8,1. Use this information to identify its group and period in the periodic table, and name the element.
模拟题3: 某原子的电子排布为2,8,1。请利用这一信息确定它在周期表中的族和周期，并说出元素名称。
utermost shell determines the group: one electron in the outer shell places it in Group 1. An atom with 2+8+1 = 11 electrons is sodium (Na). Therefore, sodium is in Group 1, Period 3.
电子层数等于周期数；这里有三个电子层被占据，因此该元素位于第3周期。最外层电子数决定族：最外层有1个电子，所以它属于第1族。电子总数为2+8+1=11个电子的原子是钠（Na）。因此钠位于第1族、第3周期。
Mock Question 4: The electronic configuration of chlorine is 2,8,7. Predict the group, period and the charge of the ion it commonly forms.
模拟题4: 氯的电子排布是2,8,7。预测它所在的族、周期和通常形成的离子电荷。
Chlorine has three occupied shells, placing it in Period 3. The outer shell contains 7 electrons, so it belongs in Group 7 (the halogens). To achieve a stable noble gas configuration, a chlorine atom gains one electron, forming a Cl⁻ ion.
氯有三个已占据的电子层，因此位于第3周期。最外层有7个电子，所以它属于第7族（卤素）。为了达到稳定的稀有气体电子排布，氯原子会得到一个电子，形成Cl⁻离子。
3. Formation of Ions | 离子的形成
Mock Question 5: Magnesium has the electronic configuration 2,8,2. Explain, in terms of electron transfer, how a magnesium atom becomes a stable ion. Write the symbol of the ion formed.
模拟题5: 镁的电子排布为2,8,2。请从电子转移的角度解释镁原子如何变成稳定的离子，并写出所形成的离子符号。
Magnesium atoms have two electrons in the outer shell. Losing these two electrons requires less energy than gaining six, so each magnesium atom loses two electrons to empty its outer shell. This leaves a full second shell with the stable electronic configuration 2,8. The loss of two negative electrons leaves behind an ion with a 2+ charge, written as Mg²⁺.
镁原子最外层有两个电子。失去这两个电子比获得六个电子所需的能量更少，因此每个镁原子失去两个电子，使最外层排空，留下具有2,8稳定结构的第二层。失去两个负电子使得该离子带2+电荷，写作Mg²⁺。
Mock Question 6: An oxygen atom has the electronic configuration 2,6. Describe the change in the number of electrons when it forms an oxide ion, and give the symbol of the ion.
模拟题6: 一个氧原子的电子排布为2,6。请描述它形成氧离子时电子数的变化，并写出离子符号。
Oxygen needs two more electrons to complete its outer shell with eight electrons (octet). It therefore gains two electrons. The oxide ion now has 2,8 configuration and carries a 2- charge because there are two more electrons than protons. The symbol is O²⁻.
氧需要再获得两个电子，才能最外层达到八个电子（八隅体）。因此它得到两个电子。氧离子现在具有2,8排布，并带2-电荷，因为电子数比质子数多两个。离子符号为O²⁻。
4. Ionic Bonding and Giant Ionic Structures | 离子键与巨型离子结构
Mock Question 7: Sodium chloride is an ionic compound. Describe the bonding in sodium chloride and explain why it has a high melting point.
模拟题7: 氯化钠是一种离子化合物。请描述氯化钠中的键合并解释为什么它具有高熔点。
In sodium chloride, sodium atoms lose one electron each to form Na⁺ ions, while chlorine atoms gain one electron each to form Cl⁻ ions. These oppositely charged ions are held together by strong electrostatic forces of attraction, called ionic bonds. The ions are arranged in a giant three-dimensional lattice. Melting the solid requires a large amount of energy to overcome these strong ionic bonds throughout the lattice, therefore the melting point is high.
在氯化钠中，每个钠原子失去一个电子形成Na⁺离子，每个氯原子得到一个电子形成Cl⁻离子。这些带相反电荷的离子通过强大的静电吸引力（离子键）结合在一起，排列成巨大的三维晶格。熔化这种固体需要大量的能量以克服晶格中强大的离子键，因此熔点很高。
Mock Question 8: Solid ionic compounds do not conduct electricity, but they do when molten or dissolved in water. Explain this observation.
模拟题8: 固态离子化合物不导电，但熔融态或溶于水时能导电。请解释这一现象。
In a solid ionic compound, the ions are fixed in position within the lattice and cannot move freely. For a substance to conduct electricity, charged particles must be mobile. When the compound is melted or dissolved in water, the ions become free to move. These mobile ions can carry electric charge, allowing the substance to conduct electricity.
在固态离子化合物中，离子被固定在晶格中，无法自由移动。物质要导电，必须有可移动的带电粒子。当化合物熔化或溶于水时，离子变为自由移动的状态。这些可移动的离子能够携带电荷，从而使物质导电。
5. Covalent Bonding and Simple Molecular Substances | 共价键与简单分子物质
Mock Question 9: Water, H₂O, is a simple molecular substance. Draw a dot-and-cross diagram to show the bonding in a water molecule, and explain why water has a relatively low boiling point.
模拟题9: 水（H₂O）是一种简单分子物质。请画出水分子键合的点叉图，并解释为什么水的沸点相对较低。
In a water molecule, the oxygen atom shares a pair of electrons with each of the two hydrogen atoms. This gives both hydrogen atoms a stable duplet (2 electrons) and oxygen a stable octet. The dot-and-cross diagram would show two bonding pairs between O and each H. Although the covalent bonds within the molecule are strong, the intermolecular forces between water molecules are weak. Only a small amount of energy is needed to overcome these weak forces, so water boils at a relatively low temperature compared with ionic compounds.
在水分子中，氧原子与两个氢原子各共用一对电子。这使得每个氢原子达到稳定的双电子结构，氧原子达到稳定的八电子结构。点叉图显示O与每个H之间有两对共用电子。虽然分子内的共价键很强，但水分子之间的分子间作用力较弱。只需要较小能量即可克服这些弱作用力，因此与离子化合物相比，水的沸点相对较低。
Mock Question 10: Carbon dioxide, CO₂, is a gas at room temperature. Explain this property using ideas about structure and bonding.
模拟题10: 二氧化碳（CO₂）在室温下是气体。请利用结构和键合的知识解释这一性质。
molecules are very weak. Very little energy is required to separate the molecules, so carbon dioxide is a gas at room temperature and has a low boiling point.
二氧化碳是一种简单分子物质。每个分子内由强的共价双键结合（O=C=O），但分子之间的作用力非常微弱。分离这些分子只需很少的能量，因此二氧化碳在室温下为气体，沸点很低。
6. Writing and Interpreting Chemical Formulae | 化学式的书写与解读
Mock Question 11: Deduce the formula of aluminium oxide. The ions involved are Al³⁺ and O²⁻.
模拟题11: 推导氧化铝的化学式。涉及的离子为Al³⁺和O²⁻。
To create a neutral compound, the total positive charge must equal the total negative charge. The lowest common multiple of 3 and 2 is 6. We need two Al³⁺ ions to give +6, and three O²⁻ ions to give -6. The formula is therefore Al₂O₃.
要形成中性化合物，总正电荷必须等于总负电荷。3和2的最小公倍数是6。需要两个Al³⁺离子贡献+6，三个O²⁻离子贡献-6。因此化学式为Al₂O₃。
Mock Question 12: What is the formula of magnesium nitrate, given that the magnesium ion is Mg²⁺ and the nitrate ion is NO₃⁻?
模拟题12: 已知镁离子为Mg²⁺，硝酸根离子为NO₃⁻，硝酸镁的化学式是什么？
The magnesium ion has a 2+ charge, while the nitrate ion has a 1- charge. To balance the charges, two nitrate ions are needed for every magnesium ion. The formula is Mg(NO₃)₂. Brackets are used to show that the subscript 2 applies to the whole nitrate group.
镁离子带2+电荷，硝酸根离子带1-电荷。为了平衡电荷，每个镁离子需要两个硝酸根离子。化学式为Mg(NO₃)₂。括号表示下标2作用于整个
Published by TutorHao | Year 9 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