Formulae, functional groups and terminology
Introduced| English | Meaning |
|---|---|
| organic chemistry/ɔːˈɡænɪk ˈkemɪstri/ | The study of these carbon compounds. |
| functional group/ˈfʌŋkʃənl ɡruːp/ | An atom or group of atoms responsible for characteristic chemical reactions of an organic compound. |
| homologous series/həˈmɒləɡəs ˈsɪəriːz/ | A family with the same functional group and general formula, whose consecutive members differ by CH₂ and have similar chemical properties. |
| molecular formula/məˈlekjʊlə ˈfɔːmjʊlə/ | A formula showing the actual numbers of atoms of each element in one molecule. |
| structural formula/ˈstrʌktʃərəl ˈfɔːmjʊlə/ | A representation showing how atoms or groups of atoms are connected in a molecule. |
The chemistry of carbon
- Carbon forms millions of compounds — far more than all other elements combined.
- Organic chemistry 有机化学 is the study of these carbon compounds.
Functional group lab
Classify organic molecules by the group that controls their reactions.
Organic chemistry is the study of compounds containing:
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Organic compounds are carbon-based.
The part of a molecule that gives a family its characteristic reactions is the:
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The functional group defines the family's chemistry.
Families and functional groups 官能团
- Organic compounds are grouped into homologous series 同系物 (families) with the same general formula.
- Each family has a functional group — the part that gives it its characteristic reactions.
Structural isomers have the same molecular formula 分子式 but different structures
A family of organic compounds with the same general formula is a ______ series.
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Members share a functional group and general formula.
Types of formula
- A molecular formula gives the number of each atom (e.g. ethane C₂H₆).
- A structural formula 结构简式 shows how the atoms are joined.
Two routes to ethanol: fermentation, and hydration of ethene
Consecutive members of a homologous series differ by:
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Each step adds one CH₂ unit.
Boiling points fall as the chain length increases in a homologous series.
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False. Boiling points rise gradually with chain length, because longer molecules have stronger forces between them.
Patterns in a series
- Members of a series differ by CH₂ each step.
- Properties change gradually (e.g. boiling point rises with chain length).
Worked example. Methane (CH₄), ethane (C₂H₆) and propane (C₃H₈) are all alkanes. Each has one more CH₂ than the last, and their boiling points rise steadily — a homologous series.
You've got it
- organic chemistry studies carbon compounds, grouped into homologous series
- each family has a functional group giving its characteristic reactions
- members differ by CH₂ and show a gradual change in properties
Write from a difference of CH2
- Methane, ethane and propane are compared.
- Each has the same kind of bonds and fits one general formula.
What is the difference between neighbouring members?
Successive members of a series differ by CH2.
How do neighbouring members of this series differ?
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The series steps up by one carbon and two hydrogens.