Carbon - Online Tutor, Practice Problems & Exam Prep

Carbon is a fundamental element in organic molecules, forming the backbone of carbohydrates, proteins, nucleic acids, and lipids. Its ability to create four covalent bonds allows for diverse molecular structures, including variations in backbone length, double bond positions, branching, and ring formations. Organic molecules contain covalently linked carbon and hydrogen, while hydrocarbons consist solely of these two elements. Understanding carbon's versatility is crucial for studying biological systems and metabolic pathways, emphasizing its role in the carbon cycle and organic chemistry.

Carbon

In this video, we're going to begin our lesson on the element carbon. Now of all the bulk elements, which recall from our previous lesson videos are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur or CHNOPS. If we exclude water, then it's actually the element carbon that is the most abundant element in living systems. And so that goes to show how important the element carbon is to living things. Now carbon is the main component of organic molecules, and really there are 4 classes of organic molecules that we're going to talk about moving forward in our course in separate videos, and those 4 classes of organic molecules are carbohydrates, proteins, nucleic acids, and lipids. And once again, carbon is the main component of these molecules. Now the terms organic molecules are really just referring to any molecule with covalently linked carbon and hydrogen atoms. And so if the molecule contains covalently linked carbon and hydrogen atoms at some point within the molecule, then we refer to it as an organic molecule. Now the term hydrocarbons, on the other hand, as its name implies, are organic molecules themselves that are only made up of carbon and hydrogen atoms, and so they contain no other elements. Again, hydrocarbons show that they only have hydrogens and carbons, whereas organic molecules that are not hydrocarbons can have other types of atoms. So just to get a better feel for this, let's take a look at our example down below, which is asking us to circle the organic molecules in green and then highlight the hydrocarbons in yellow.

When we take a look at these structures that we have down below, notice that this molecule over here has a carbon covalently bound to a hydrogen, so that makes it an organic molecule. Then notice this one over here has an oxygen bonded to hydrogens, and this is a water molecule. But water molecules are not organic molecules because they don't have covalently linked carbon and hydrogen atoms. So this is not going to be an organic molecule. Notice this over here is CO₂ or carbon dioxide, and once again, CO₂ does not have covalently linked carbon and hydrogen atoms, so this is not going to be an organic molecule. Now notice that this one over here does have carbon and hydrogen covalently linked together so that makes this an organic molecule. Then last but not least over here, notice that this one also has carbon and hydrogen bound, and so that also makes it an organic molecule. Now to identify the hydrocarbons, the hydrocarbons are going to be organic molecules that are only made of carbon and hydrogen atoms. So if we take a look at option a over here, notice that this is methane, which is only made up of carbon and hydrogen atoms. So that makes this a hydrocarbon. The same goes for option d over here. It is only containing carbon and hydrogen atoms. So once again, that makes this a hydrocarbon. But then notice that this last one over here has an oxygen atom over here, and so it is not only made up of carbon and hydrogen atoms if it has an oxygen in it. And so this one is an organic molecule but it is not a hydrocarbon.

As we see here, this is the correct answer to this example. And so, this here concludes our introduction to carbon and we'll get to talk a little bit more about the element carbon in our next lesson video. So, I'll see you all there.

Organic molecules are defined as chemical compounds that contain:

a) Carbon.

b) Carbon & Oxygen.

c) Carbon & Nitrogen.

d) Carbon & Hydrogen.

• A. Carbon.
• B. Carbon & Oxygen.
• C. Carbon & Nitrogen.
• D. Carbon & Hydrogen.

Carbon is an Excellent Building Block

So the element carbon is actually an excellent building block and so in this video we're going to focus on that idea. Now carbon's ability to form a total of 4 covalent bonds really is what makes it such a flexible atomic building block for building a variety of different types of molecules. And so the carbon backbones of organic molecules such as carbohydrates, proteins, nucleic acids, or lipids can actually vary in 4 different ways that we have listed down below right here. And those are in the length of the carbon backbone, the position of double bonds within the carbon backbone, the branch points of the carbon backbone, and the carbon backbone being in either a linear form or a ring form. And so if we take a look at our example image down below, we can take a look at the variations of carbon backbones. And so over here in the first image, what we're showing you is how, number 1, which of course corresponds with number 1 up above, is that the length of carbon backbones, are capable of changing. And so notice that this first molecule over here has 2 carbons in its carbon backbone, whereas this molecule over here has 3 carbon atoms in its backbone. And so you'll see different molecules throughout that have different lengths of the carbon backbone. And so that's the first characteristic of the carbon backbones. Now the second one are the positions of double bonds within the carbon backbone. So notice that this molecule over here has a double bond between the first 2 carbons in the carbon backbone, whereas this molecule over here has a double bond between the 2nd and the 3rd carbon atoms in the carbon backbone, and so the position of the double bond can vary. Now the third characteristic here of carbon backbones are the branch points, and so, of course, you can have a linear carbon backbone that does not have any branch points, but notice this molecule over here actually has a carbon backbone and another backbone that is branching off of it, and so here we have a branched carbon backbone. Now the 4th and final characteristic here are the ring forms. And so, of course, we've seen examples of the carbon backbone being in a linear form like all of these, but the ones that you see down below show that the carbon backbone can be in a ring form as we see over here and over here, and notice that the ring form can also have double bonds, within it as well. And so this here just goes to show how a lot of the molecules that we're going to talk about moving forward, they're going to be built using carbon as the backbone. And carbon is a really useful atomic building block because it can be built in so many different fashions as we see right here, and that's really the main takeaway here of this video. And so that concludes our lesson on how carbon is such an excellent building block and we'll be able to see these concepts applied as we move forward throughout our course. So I'll see you all in our next video.

Here’s what students ask on this topic:

What are the four classes of organic molecules that contain carbon?

The four classes of organic molecules that contain carbon are carbohydrates, proteins, nucleic acids, and lipids. Carbohydrates are composed of carbon, hydrogen, and oxygen, and they serve as a primary energy source. Proteins, made up of amino acids, are essential for various cellular functions and structures. Nucleic acids, such as DNA and RNA, store and transmit genetic information. Lipids, which include fats, oils, and phospholipids, are important for energy storage, membrane structure, and signaling. Carbon's ability to form four covalent bonds allows these molecules to have diverse and complex structures, making it a fundamental element in organic chemistry and biology.

Why is carbon considered an excellent building block for organic molecules?

Carbon is considered an excellent building block for organic molecules because it can form four covalent bonds, allowing for a wide variety of molecular structures. This versatility enables carbon to create long chains, branched structures, and ring formations. Additionally, carbon can form single, double, and triple bonds, further increasing the diversity of possible molecules. These properties make carbon essential for the formation of complex organic molecules such as carbohydrates, proteins, nucleic acids, and lipids, which are crucial for life. Carbon's ability to bond with many other elements, including hydrogen, oxygen, nitrogen, and sulfur, also contributes to its central role in organic chemistry.

What is the difference between organic molecules and hydrocarbons?

Organic molecules are compounds that contain covalently linked carbon and hydrogen atoms, and they may include other elements such as oxygen, nitrogen, sulfur, and phosphorus. Examples include carbohydrates, proteins, nucleic acids, and lipids. Hydrocarbons, on the other hand, are a specific type of organic molecule that consist solely of carbon and hydrogen atoms. They do not contain any other elements. Examples of hydrocarbons include methane (CH₄), ethane (C₂H₆), and benzene (C₆H₆). While all hydrocarbons are organic molecules, not all organic molecules are hydrocarbons.

How do variations in carbon backbones contribute to molecular diversity?

Variations in carbon backbones contribute to molecular diversity in several ways. First, the length of the carbon backbone can vary, resulting in molecules with different sizes and properties. Second, the position of double bonds within the carbon backbone can change, affecting the molecule's reactivity and shape. Third, carbon backbones can have branch points, leading to branched structures that differ from linear ones. Finally, carbon backbones can form ring structures, which can also include double bonds. These variations allow for a vast array of molecular configurations, enabling the formation of diverse organic molecules essential for life.

What role does carbon play in the carbon cycle?

Carbon plays a crucial role in the carbon cycle, which is the process by which carbon is exchanged between the atmosphere, oceans, soil, and living organisms. In the carbon cycle, carbon dioxide (CO₂) is absorbed by plants during photosynthesis to produce organic molecules like glucose. These molecules are then consumed by animals and other organisms, which use them for energy and growth. When organisms respire, decompose, or burn fossil fuels, CO₂ is released back into the atmosphere. This continuous exchange of carbon is essential for maintaining the balance of carbon in the environment and supporting life on Earth.