Common functional groups
Cl, Br, OH, CHO, CO and COOH.
Labels on a chain
A carbon chain can carry different groups in place of hydrogen. Each group gives its own kind of compound.
Which group do you think marks a carboxylic acid?
What this lesson covers
The idea
Important functional groups are —Cl or —Br (haloalkanes), —OH (alcohols), —CHO (aldehydes), —CO— (ketones) and —COOH (carboxylic acids), each attached to the carbon chain by replacing hydrogen through its free valency.
Labels on a chain
A carbon chain can carry different groups in place of hydrogen. Each group gives its own kind of compound.
Which group do you think marks a carboxylic acid?
- -COOH
- -OH
- -Cl
Five groups
Open every tab. A dashed line is the free valency by which the group attaches to the carbon chain.
A group takes the place of hydrogen
The group is attached to the carbon chain through its free valency, replacing one hydrogen atom of the chain.
Important functional groups are -Cl or -Br (haloalkanes), -OH (alcohols), -CHO (aldehydes), -CO- (ketones) and -COOH (carboxylic acids), each attached to the carbon chain by replacing hydrogen through its free valency.
- Functional group | Class of compounds
- -Cl, -Br | haloalkanes
- -OH | alcohols
- -CHO | aldehydes
- -CO- | ketones
- -COOH | carboxylic acids
Notes
Important functional groups are -Cl or -Br (haloalkanes), -OH (alcohols), -CHO (aldehydes), -CO- (ketones) and -COOH (carboxylic acids). Each is attached to the carbon chain by replacing hydrogen through its free valency.
Check yourself
Which functional group marks an alcohol?
Which functional group marks a carboxylic acid?
Which functional group marks a ketone?
How is a functional group attached to the carbon chain?
- -COOH. -COOH marks a carboxylic acid.
- -OH — correct. Yes!
- -CHO. -CHO marks an aldehyde.
- -CO-. -CO- marks a ketone.
- -OH. -OH marks an alcohol.
- -COOH — correct. Yes!
- -CO- — correct. Yes!
- -CHO. -CHO marks an aldehyde.
- -Cl. -Cl marks a haloalkane.
- It is added on top of all the hydrogen atoms. The group takes the place of a hydrogen atom, so the valency of carbon stays satisfied.
- Through its free valency, replacing a hydrogen atom — correct. Yes!
- It is mixed in without any bond. The group is joined to the chain through its free valency.