OxfordAQA International AS Chemistry Unit 1 Physical Content | 牛津AQA国际AS化学第一单元物理内容

📚 OxfordAQA International AS Chemistry Unit 1 Physical Content | 牛津AQA国际AS化学第一单元物理内容

This revision guide covers the physical chemistry content commonly tested in OxfordAQA International AS Chemistry Unit 1. It includes atomic structure, amount of substance, bonding, energetics, kinetics, equilibria and redox, with key ideas matched to the AS data sheet and topic-test style questions.

本复习指南覆盖牛津AQA国际AS化学第一单元中常考的物理化学内容，包括原子结构、物质的量、化学键、能量学、动力学、平衡和氧化还原，并配合AS数据手册与单元测试题型讲解核心要点。

1. Atomic Structure and the Mass Spectrometer | 原子结构与质谱仪

Atoms contain protons, neutrons and electrons. Protons have a relative mass of 1 and charge +1; neutrons have a relative mass of 1 and charge 0; electrons have a relative mass of 1/1840 and charge -1. The atomic number Z is the number of protons, and the mass number A is the number of protons plus neutrons.

原子由质子、中子和电子组成。质子相对质量为1，电荷为+1；中子相对质量为1，电荷为0；电子相对质量约为1/1840，电荷为-1。原子序数Z等于质子数，质量数A等于质子数与中子数之和。

⁴He, ¹²C, ³⁵Cl and ³⁷Cl are common isotopes. Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.

⁴He、¹²C、³⁵Cl 和 ³⁷Cl 是常见同位素。同位素是同种元素中质子数相同而中子数不同的原子。

A mass spectrometer measures relative atomic mass through ionisation, acceleration, deflection and detection. The amount of deflection depends on the mass-to-charge ratio, m/z.

质谱仪通过电离、加速、偏转和检测四个阶段测定相对原子质量。偏转程度取决于质荷比 m/z。

2. Relative Atomic Mass from Mass Spectra | 从质谱图计算相对原子质量

Relative atomic mass, Ar, is the weighted average mass of an element’s isotopes relative to 1/12 of the mass of a carbon-12 atom. For chlorine, 75.77% ³⁵Cl and 24.23% ³⁷Cl gives Ar = (75.77 × 35 + 24.23 × 37) ÷ 100 = 35.5.

相对原子质量 Ar 是元素各同位素相对于碳-12原子质量1/12的加权平均质量。氯由75.77%的³⁵Cl和24.23%的³⁷Cl组成，Ar = (75.77 × 35 + 24.23 × 37) ÷ 100 = 35.5。

On a mass spectrum, the height of each peak is proportional to isotopic abundance. Multiply each m/z value by its abundance, add the results, and divide by the total abundance.

在质谱图中，每个峰的高度与同位素丰度成正比。将每个 m/z 值乘以其丰度，求和后再除以总丰度。

Mass spectra can also show fragmentation patterns. The peak with the highest m/z value usually corresponds to the molecular ion, M⁺, giving relative molecular mass.

质谱图还可以显示碎片峰。m/z值最大的峰通常对应分子离子 M⁺，可用于确定相对分子质量。

3. The Mole and Molar Mass | 物质的量与摩尔质量

One mole contains exactly 6.022 × 10²³ particles, known as the Avogadro constant Nₐ. Molar mass M is the mass of one mole of a substance and has units g mol⁻¹.

1摩尔含6.022 × 10²³个微粒，称为阿伏伽德罗常数 Nₐ。摩尔质量 M 是1摩尔物质的质量，单位为 g mol⁻¹。

n = m ÷ M

where n is amount of substance in mol, m is mass in g, and M is molar mass in g mol⁻¹.

其中 n 为物质的量（mol），m 为质量（g），M 为摩尔质量（g mol⁻¹）。

• Calculate moles of 0.50 g CaCO₃: M = 100.1 g mol⁻¹, so n = 0.50 ÷ 100.1 = 0.0050 mol.
• 计算0.50 g CaCO₃的物质的量：M = 100.1 g mol⁻¹，因此 n = 0.50 ÷ 100.1 = 0.0050 mol。

Avogadro constant conversions are common in topic tests. To find number of particles, multiply moles by 6.022 × 10²³; to

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