📚 Fundamentals of Organic Chemistry | 有机化学基础
Organic chemistry is the study of carbon-containing compounds and their properties, structures, and reactions. It underpins everything from biological processes to modern materials, fuels, and pharmaceuticals. In IB Chemistry, mastering the fundamentals of organic chemistry means understanding how carbon atoms bond, how molecules are classified and named, the nature of isomerism, and the main categories of organic reactions. This article provides a structured overview of these core concepts, pairing English explanations with Chinese translations to support bilingual learners.
有机化学是研究含碳化合物及其性质、结构和反应的科学。它是生物过程、现代材料、燃料和制药的基础。在 IB 化学中，掌握有机化学基础意味着理解碳原子如何成键、分子如何分类和命名、异构现象的本质以及有机反应的主要类别。本文将结构化地概述这些核心概念，通过英文解释与中文翻译配对的方式帮助双语学习者。
1. Defining Organic Chemistry | 有机化学的定义
Originally, the term 'organic' referred to compounds obtained from living organisms, but today organic chemistry is defined as the chemistry of carbon compounds. A few carbon-containing species are treated as inorganic exceptions: carbon monoxide (CO), carbon dioxide (CO₂), carbonates (CO₃²⁻), hydrogencarbonates (HCO₃⁻), and cyanides (CN⁻). All other compounds of carbon are considered organic, and they almost always contain hydrogen. Oxygen, nitrogen, sulfur, phosphorus, and the halogens are also frequently present.
‘有机’这个术语最初指从生物体中获得的化合物，但现在有机化学被定义为碳化合物的化学。少数含碳物种被视为无机例外：一氧化碳 (CO)、二氧化碳 (CO₂)、碳酸盐 (CO₃²⁻)、碳酸氢盐 (HCO₃⁻) 和氰化物 (CN⁻)。所有其他碳的化合物都被视为有机物，它们几乎总含有氢。氧、氮、硫、磷和卤素也经常出现。
Organic molecules range from simple hydrocarbons like methane (CH₄) to staggeringly complex biomolecules like DNA. The key to this diversity lies in the bonding capabilities of carbon, which is examined next.
有机分子的范围从像甲烷 (CH₄) 这样的简单烃类到 DNA 这样极为复杂的生物分子。这种多样性的关键在于碳的成键能力，接下来将进行探讨。
2. The Versatility of Carbon | 碳的多功能性
Carbon is in Group 14 of the periodic table and has four valence electrons. It achieves a stable octet by forming four covalent bonds, giving rise to tetrahedral, trigonal planar, or linear geometries depending on the number of bonding domains. The ability to form strong C–C bonds (catenation) allows the construction of chains, branched structures, and rings.
碳位于元素周期表第 14 族，拥有四个价电子。它通过形成四个共价键达到稳定的八体结构，根据成键域的数目产生四面体、平面三角形或直线型几何构型。形成强 C–C 键的能力（自链结合）使得链、支链和环状结构的构建成为可能。
Carbon’s electronegativity (2.5 on the Pauling scale) is intermediate, so its bonds with hydrogen are fairly non-polar, while bonds with oxygen or nitrogen are polar. This polarity, combined with the presence of multiple bonds, creates functional groups that control a molecule’s reactivity. The existence of single, double, and triple bonds between carbon atoms leads to saturated and unsaturated compounds—a classification that heavily influences chemical behaviour.
碳的电负性（鲍林标度为 2.5）处于中间水平，因此它与氢形成的键相当非极性，而与氧或氮形成的键则是极性的。这种极性，加上多重键的存在，产生了控制分子反应活性的官能团。碳原子之间单键、双键和三键的存在导致了饱和和不饱和化合物——这种分类对化学行为有重大影响。
3. Representing Organic Molecules | 有机分子&
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