📚 Edexcel A-Level Chemistry Topic 6: Organic Chemistry I | 爱德思A-Level化学专题6：有机化学I
Organic chemistry is the branch of chemistry that explores the structure, properties and reactions of carbon-based compounds. In Edexcel A-Level Chemistry Topic 6, students build the core toolkit of organic chemistry: from naming molecules and recognising functional groups to writing mechanisms for alkanes, alkenes, halogenoalkanes and alcohols. Mastering this topic is essential because it underpins almost every later organic chemistry unit, including carbonyls, aromatic chemistry and nitrogen compounds in Topics 17 and 18.
有机化学是研究碳基化合物的结构、性质与反应的化学分支。在爱德思A-Level化学专题6中，学生将建立有机化学的核心工具箱：从分子命名、官能团识别，到书写烷烃、烯烃、卤代烷和醇的反应机理。掌握本专题至关重要，因为它几乎是后续所有有机化学单元的基础，包括专题17和18中的羰基化合物、芳香族化学和含氮化合物。
1. Carbon Skeleton and Homologous Series | 碳骨架与同系物
Carbon has four valence electrons, so it forms four covalent bonds with hydrogen, oxygen, nitrogen, halogens and other carbon atoms. This allows carbon to form long chains, branched chains and rings, which are the backbone of millions of organic molecules.
碳有四个价电子，因此它能与氢、氧、氮、卤素和其他碳原子形成四个共价键。这使得碳能够形成长直链、支链和环状结构，成为数百万种有机分子的骨架。
A homologous series is a family of organic compounds with the same general formula and the same functional group. Each successive member differs from the previous one by a CH₂ unit, so physical properties change gradually down the series while chemical properties remain similar.
同系物是一组具有相同通式和相同官能团的有机化合物家族。相邻成员之间相差一个CH₂单元，因此物理性质沿同系物逐渐变化，而化学性质保持相似。
Alkanes: CₙH₂ₙ₊₂ | Alkenes: CₙH₂ₙ | Alcohols: CₙH₂ₙ₊₁OH
2. Functional Groups and Formula Types | 官能团与分子式类型
l groups tested at A-Level include the alkene double bond C=C, halogenoalkane R-X, alcohol –OH, aldehyde –CHO, ketone –CO–, carboxylic acid –COOH, nitrile –CN and amine –NH₂.
官能团是决定分子特征反应的原子或原子团。A-Level常考的官能团包括烯烃双键C=C、卤代烷R-X、醇–OH、醛–CHO、酮–CO–、羧酸–COOH、腈–CN和胺–NH₂。
You must be able to convert between empirical formula, molecular formula, structural formula, displayed formula and skeletal formula. The displayed formula shows every atom and bond, while the skeletal formula uses line notation where each vertex and terminal point represents a carbon atom.
你必须能够在实验式、分子式、结构式、显示式和骨架式之间相互转换。显示式画出所有原子和键，而骨架式使用线键表示法，其中每个顶点和端点代表一个碳原子。
| Formula type | Example for ethanol |
| Empirical | C₂H₆O |
| Molecular | C₂H₆O |
| Structural | CH₃CH₂OH |
| Displayed | H H | | H-C-C-O-H | | H H |
| Skeletal | OH / line notation |
3. IUPAC Nomenclature | IUPAC命名法
IUPAC names are built from a prefix, a parent chain and a suffix. The parent chain is the longest continuous carbon chain containing the principal functional group. Number the chain so that the functional group or substituents get the lowest possible locants.
IUPAC名称由前缀、母体链和后缀组成。母体链是包含主官能团的最长连续碳链。给碳链编号时，应使官能团或取代基获得尽可能小的位次。
thylbut-1-ene, not 2-methylbut-3-ene, because the double bond must have the lowest number.
对于多个相同取代基，使用前缀二、三、四。数字之间用逗号分隔，数字与文字之间用连字符分隔。例如CH₃CH(CH₃)CH=CH₂应命名为3-甲基丁-1-烯，而不是2-甲基丁-3-烯，因为双键必须获得最低位次。
CH₃CH(CH₃)CH=CH₂ → 3-methylbut-1-ene | 3-甲基丁-1-烯
4. Structural Isomerism | 结构异构
Structural isomers have the same molecular formula but different structural formulae. Chain isomers differ in the arrangement of the carbon skeleton, such as butane and methylpropane.
结构异构体具有相同的分子式但不同的结构式。碳链异构体的碳骨架排列不同，例如丁烷和甲基丙烷。
Position isomers have the same functional group but at different positions on the chain, such as propan-1-ol and propan-2-ol. Functional group isomers have different functional groups, such as ethanol CH₃CH₂OH and methoxymethane CH₃OCH₃.
位置异构体具有相同的官能团，但位于碳链的不同位置，例如丙-1-醇和丙-2-醇。官能团异构体具有不同的官能团，例如乙醇CH₃CH₂OH和甲醚CH₃OCH₃。
5. Stereoisomerism: E/Z | 立体异构：E/Z
e freely, so if each carbon of the C=C carries two different groups, E/Z isomerism arises.
立体异构体具有相同的结构式，但原子的空间排列不同。烯烃中的碳碳双键不能自由旋转，因此如果C=C的每个碳原子上连有两个不同的基团，就会产生E/Z异构。
Assign priorities using the Cahn-Ingold-Prelog rule: higher atomic number means higher priority. In the E isomer, the two higher-priority groups are on opposite sides of the double bond. In the Z isomer, they are on the same side.
使用Cahn-Ingold-Prelog规则确定优先顺序：原子序数越大，优先顺序越高。在E异构体中，两个高优先基团位于双键的异侧。在Z异构体中，它们位于同侧。
Cis-trans is a special case of E/Z when identical groups are present.
6. Alkanes: Properties and Reactions | 烷烃：性质与反应
Alkanes are saturated hydrocarbons with only single C-C and C-H bonds. Their general formula is CₙH₂ₙ₊₂. The main intermolecular forces are weak London forces, so boiling points increase with increasing chain length because there are more electrons and a larger surface area for temporary dipoles.
烷烃是只含C-C和C-H单键的饱和烃，通式为CₙH₂ₙ₊₂。分子间主要作用力是弱的伦敦力，因此沸点随碳链增长而升高，因为电子数更多、临时偶极的表面积更大。
Branched alkanes have
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