Formulas, functional groups and naming
| English | Chinese | Pinyin |
|---|---|---|
| hydrocarbon | 碳氢化合物 | tàn qīng huà hé wù |
| alkane | 烷烃 | wán tīng |
| functional group | 官能团 | guān néng tuán |
Naming the carbon compounds
- A hydrocarbon 碳氢化合物 contains only carbon and hydrogen; alkanes 烷烃 are the simplest.
- A functional group 官能团 is the reactive part that decides a molecule's properties.
- We draw molecules in several ways and name them systematically.
Functional group lab
Sort organic molecules by the group that controls their reactions.
A functional group is:
Molecules with the same functional group behave alike, because the group is the reactive part.
A group of atoms that gives an organic molecule its characteristic reactions is a ______ group.
e.g. –OH, –COOH.
Types of formula
| Formula | What it shows |
|---|---|
| general | the pattern for a family — alkanes are $\text{C}_n\text{H}_{2n+2}$ |
| molecular | the actual atom counts — $\text{C}_4\text{H}_{10}$ |
| structural | the groups in order — $\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_3$ |
| displayed | every atom and bond drawn |
| skeletal | lines for bonds; carbons at corners, H on carbon hidden |
Chain, positional and functional-group structural isomerism
The general formula of the alkanes is:
Alkanes follow CₙH₂ₙ₊₂ (e.g. C₄H₁₀ for butane).
In a skeletal formula:
Skeletal formulas use a zigzag of lines; carbon atoms are the corners/ends and their hydrogens are implied.
Match each organic term to its meaning.
Each item links the term to its correct meaning.
Naming
- A stem for the carbon count: meth- (1), eth- (2), prop- (3), but- (4), pent- (5), hex- (6).
- An ending for the functional group, and numbers to show where groups are.
Crude oil is a complex mixture of hydrocarbons
Which stem is used for a chain of four carbons?
meth=1, eth=2, prop=3, but=4, pent=5, hex=6.
Naming pitfalls
- Number the carbon chain from the end that gives the functional group the lowest number.
- Check the suffix matches the family: -ane, -ene, -ol, -al, -one, -oic acid.
You've got it
- a functional group is the reactive part; same group → similar properties
- formulas: general ($\text{C}_n\text{H}_{2n+2}$) / molecular / structural / displayed / skeletal
- name with a stem (meth/eth/prop/but…) + an ending + numbers