Alkenes · 烯烃
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| double bond/ˈdʌbl bɒnd/ | 双键 | shuāng jiàn |
| alkenes/ˈælkiːnz/ | 烯烃 | xī tīng |
| unsaturated/ʌnˈsætʃəreɪtɪd/ | 不饱和 | bù bǎo hé |
| addition reactions/əˈdɪʃn rɪˈækʃnz/ | 加成反应 | jiā chéng fǎn yìng |
| bromine water/ˈbrəʊmaɪn ˈwɔːtə/ | 溴水 | xiù shuǐ |
The double-bond 双键 family
- The alkenes 烯烃 look similar to alkanes but have one crucial difference: a double bond.
- That double bond makes them much more reactive.
双键的族
- 烯烃(alkenes)看起来与烷烃相似,但有一个关键的区别:一个双键。
- 那个双键使它们活泼得多。
Alkenes contain a: · 烯烃含有一个:
The C=C double bond defines alkenes. · C=C 双键定义烯烃。
The general formula of the alkenes is: · 烯烃的通式是:
Alkenes follow CₙH₂ₙ. · 烯烃遵循 CₙH₂ₙ。
The simplest alkene, with two carbon atoms, is . · 最简单的烯烃,有两个碳原子,是。
Ethene is C₂H₄. · 乙烯是 C₂H₄。
The alkene family
- Alkenes have the general formula CₙH₂ₙ and contain a carbon–carbon double bond.
- Examples: ethene (C₂H₄), propene (C₃H₆).
Alkenes are unsaturated — they contain a C=C double bond, unlike the saturated alkanes
烯烃族
- 烯烃有通式 CₙH₂ₙ 并含有一个碳—碳双键。
- 例子:乙烯(C₂H₄)、丙烯(C₃H₆)。
烯烃是不饱和的——它们含有一个 C=C 双键,不像饱和的烷烃
Addition across the C=C double bond · 加到 C=C 双键两端
Step through an addition reaction. The C=C double bond is an alkene's reactive spot — molecules add right across it, which also gives the bromine-water test. · 逐步看一个加成反应。C=C 双键是一个烯烃的活泼点——分子直接加到它两端,这也给出溴水测试。
Alkenes are unsaturated because of their double bond. · 烯烃因为它们的双键而是不饱和的。
The double bond can open to add atoms. · 双键能打开以加上原子。
Unsaturated 不饱和
- Alkenes are unsaturated — they have a double bond that can open up.
- This lets other atoms add across the double bond (addition reactions 加成反应).
不饱和
- 烯烃是不饱和的(unsaturated)——它们有一个能打开的双键。
- 这让其他原子能加到双键两端(加成反应)。
Bromine water added to an alkene turns: · 加到一个烯烃的溴水变成:
The bromine adds across the double bond, decolourising. · 溴加到双键两端,脱色。
Testing for a double bond
- Add bromine water 溴水 to an alkene: it turns from orange to colourless.
- This is the test that distinguishes alkenes (unsaturated) from alkanes (saturated).
Worked example. Shake an unknown hydrocarbon with orange bromine water. If it turns colourless, the compound is an alkene (the bromine adds across the double bond). If it stays orange, it's an alkane.
The bromine water test: an alkene decolourises the orange bromine water, while an alkane leaves it orange
检验双键
- 给烯烃加溴水(bromine water):它从橙色变无色。
- 这是区分烯烃(不饱和)和烷烃(饱和)的测试。
例题。 把一个未知的碳氢化合物与橙色的溴水摇晃。如果它变无色,该化合物是一个烯烃(溴加到双键两端)。如果它保持橙色,它是一个烷烃。
溴水测试:一个烯烃使橙色溴水褪色,而一个烷烃使它保持橙色
You've got it
- alkenes are unsaturated (a C=C double bond), formula CₙH₂ₙ
- the double bond lets atoms add across it (addition reactions)
- the test: bromine water turns from orange to colourless with an alkene
你掌握了
- 烯烃是不饱和的(一个 C=C 双键),式为 CₙH₂ₙ
- 双键让原子加到它两端(加成反应)
- 测试:溴水与一个烯烃从橙色变无色