Nathan I. answered 04/22/19
Patient, Knowledgeable Tutor in Chemistry
Organic chemistry studies molecules called hydrocarbons. Hydrocarbons are chains of carbons, with hydrogens on the carbons so that each carbon has a full octet. These chains can also have other elements as well, like oxygens, nitrogens, and halogens (fluorine, chlorine, bromine and iodine) to name the most common. These elements can change the properties of bydrocarbons, including how a hydrocarbon reacts. This is why they are called functional groups. In many reactions, these groups can be changed to give new kinds of hydrocarbons. For example, ethyl bromide:
Ethyl bromide can react with a hydroxide ion:
CH3CH2Br + HO- ------> CH3CH2OH + Br-
To form ethanol:
and will remove the bromine atom. This reaction is called a substitution reaction, as one group substitutes another's place on a hydrocarbon. If a hydrocarbon has an -OH group bonded to one of its carbons, it's called an alcohol (any chemical name ending with "-ol" tells you the chemical has this group). This is only one of many organic chemistry reactions that chemists use. Hopefully this gives you some idea of what the field is like.