Organic structures and reaction pathways
| English | 中文 | Pinyin |
|---|---|---|
| functional group/ˈfʌŋkʃənl ɡruːp/ | 官能团 | guān néng tuán |
| isomer/ˈaɪsəmə/ | 异构体 | yì gòu tǐ |
What would explain this observation?
- Two compounds can have the same molecular formula but different structures. Their functional groups 官能团 help predict which reactions they undergo.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- A homologous series shares a functional group and general formula. Structural isomers 异构体 share a molecular formula but differ in atom connections. Alkenes contain a carbon-carbon double bond.
- functional group: An atom group determining characteristic reactions; isomer: A compound sharing a formula but differing in structure.
What happens to the carbon skeleton when bromine adds to ethene?
Distinguish addition, substitution, oxidation and polymerization by tracing bonds before and after reaction. Conditions and reagents belong to the reaction arrow; they are not interchangeable labels.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Distinguish addition, substitution, oxidation and polymerization by tracing bonds before and after reaction. Conditions and reagents belong to the reaction arrow; they are not interchangeable labels.
- Draw displayed formulae with correct carbon and hydrogen valencies. For the specified alkene additions, keep the carbon skeleton and track the atoms added across C=C. Compare the supplied structure before and after reaction. GCSE 8462 does not require an advanced multistep synthesis route in this focus.
Which two habits make the investigation or model in this case more defensible?
Draw displayed formulae with correct carbon and hydrogen valencies. For the specified alkene additions, keep the carbon skeleton and track the atoms added across C=C. Compare the supplied structure before and after reaction. GCSE 8462 does not require an advanced multistep synthesis route in this focus.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: ethene adds bromine across its double bond. The two-carbon skeleton stays intact and each carbon gains one bromine atom, giving 1,2-dibromoethane. One mole of ethene reacts with one mole of bromine in this addition reaction.
How many moles of bromine react completely with 0.15 mol ethene? Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
How many moles of bromine react completely with 0.15 mol ethene?
The result is 0.15 mol. Known: ethene adds bromine across its double bond. The two-carbon skeleton stays intact and each carbon gains one bromine atom, giving 1,2-dibromoethane. One mole of ethene reacts with one mole of bromine in this addition reaction.
Check the conclusion and its limits
- Bromine decolourization provides evidence of unsaturation in an appropriate test. It is not proof that an unknown sample is specifically ethene.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Compounds with the same molecular formula always have identical properties. This claim is false: Bromine decolourization provides evidence of unsaturation in an appropriate test. It is not proof that an unknown sample is specifically ethene.
Organic structures and reaction pathways: Distinguish addition, substitution, oxidation and polymerization by tracing bonds before and after reaction. Conditions and reagents belong to the reaction arrow; they are not interchangeable labels.
Compounds with the same molecular formula always have identical properties.
Bromine decolourization provides evidence of unsaturation in an appropriate test. It is not proof that an unknown sample is specifically ethene.
An atom group determining characteristic reactions: write the technical term.
functional group means An atom group determining characteristic reactions.