Introduction to Organic Molecules I: Functional Groups

Lesson Transcript
Instructor: Meg Desko

Meg has taught college-level science. She holds a Ph.D. in biochemistry.

Organic molecules contain carbon and other atoms often found together and behaving similarly are called functional groups. Learn about carbon and atoms in functional groups in this introduction to organic molecules. Updated: 08/12/2021

What Is Organic Chemistry?

What do you think of when you think of when you hear the word organic? Do you think of the baby carrots that you saw in the grocery store the other day or do you think of something entirely different?

When we talk about organic foods, we mean that they were grown using only natural fertilizers. Now, what does this have to do with chemistry? Well, it turns out that for a long time chemists have been studying the molecules that make up living things, and for a long time they called this organic chemistry.

To them, organic chemistry was the study of molecules that came from living things and from formerly living things. These molecules included sugars (such as glucose), proteins and the amino acids that make them up (such as glycine), fats and also hydrocarbons (such as methane - which you know is natural gas - and octane - which is a component of gasoline) which are molecules that came from things that used to be living.

Organic chemistry is the study of molecules that contain carbon
Organic Molecules Contain Carbon

At some point, scientists decided that they were going to start making these types of molecules synthetically. So the old definition no longer fit. Organic chemistry could not just be the study of molecules that came from living things, but it needed to be a little bit broader. So, scientists looked at the different kinds of molecules from living things and found that they all contain carbon.

This leads us to our new definition of organic chemistry, which is the study of molecules that contain carbon.

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Introduction to Organic Molecules II: Monomers and Polymers

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 1:40 Functional Groups
  • 3:41 Hydroxyl
  • 4:34 Amine
  • 5:17 Ether
  • 5:48 Carbonyl
  • 6:47 Ester
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

What are Functional Groups?

Now, if all these molecules were like methane and octane (containing only carbon and hydrogen), life wouldn't be exciting. In fact, life probably wouldn't exist, since these molecules mostly sit around interacting with other like molecules. Unless oxygen and fire come along - in which case, they burn and turn into carbon dioxide and water. Since we're not running around as flaming people, this means there must be a little more to the story. It turns out, this is true.

While organic chemistry is the study of molecules that contain carbon, they also contain other atoms. So, organic molecules can contain carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur. All of these atoms come together to make what we call functional groups.

Functional groups are groups of atoms that we often find together that have a specific behavior. They're also a really good way to help you recognize different classes of molecules because different types of molecules contain different functional groups.

Now, think of it as if you're going to go on an or a date. You've never met this person before, so you need to remember what he or she looks like. So you look at the profile and say: this person whose name is ChemistryIsAwesome has glasses, brown hair and he or she is about 5-foot, 8-inches. All of this information gives you some idea of what this person looks like and how you will recognize him or her. That is exactly what functional groups do for us when we meet new biological molecules.

The hydroxyl group consists of an oxygen atom single-bonded to a hydrogen and to a carbon group
Hydroxyl Group

So, as we meet new biological molecules, functional groups can help us to recognize them because each of the different types of biological molecules has a characteristic set of functional groups. So, we're going to go meet the functional groups now.

Hydroxyl Group

The first functional group we're going to meet is the alcohol or hydroxyl group. Now, looking at the name hydroxyl you might think this thing probably contains hydrogen and oxygen. If that's what you're thinking right now, you're right.

A hydroxyl group is an oxygen atom that is single-bonded to hydrogen and is also single-bonded to a carbon-containing group. A common alcohol that you probably know is ethanol, which can be used as a cleaner and is the alcohol that is found in alcoholic beverages.

So the general picture of an alcohol is that it is a group that contains carbon attached to oxygen, which is single-bonded to hydrogen. A lot of times, chemists use the shorthand R to talk about something that contains carbon. In some cases, it can be carbon or hydrogen, but in the case of an alcohol, it's always a carbon, because if it was not a carbon-containing group then it would be water.

Amine Group

The next functional group I'd like to introduce you to is the amine. The simplest amine is ammonia and is often found in bathroom cleaners. It has a very simple chemical structure which is a nitrogen atom that is bonded to three hydrogen atoms. It's quite small and quite volatile, and that's why it has a very pungent smell.

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it now
Create an account to start this course today
Used by over 30 million students worldwide
Create an account