Carbon compounds are chemical compounds that contain the element carbon. There are more carbon compounds than compounds of any other element except hydrogen. Most of them are organic compounds, but inorganic carbon compounds also exist. Here is a look at examples of carbon compounds, the type of chemical bonds they contain, and how carbon compounds are classified.
Examples of Carbon Compounds
All organic and organometallic compounds and some inorganic compounds contain carbon. Examples of carbon compounds include:
- carbon dioxide (CO2)
- deoxyribonucleic acid (DNA)
- glucose (C₆H₁₂O₆)
- methane (CH4)
- benzene (C6H6)
- ethanol (C₂H₆O)
- hydrogen cyanide (HCN)
- silicon carbide (SiC)
- phosgene (COCl2)
- carbonic acid (H2CO3)
- carbon tetrafluoride (CF4)
- acetic acid (CH₃COOH)
- tetraethyl lead [(CH₃CH₂)₄Pb]
Classifying Carbon Compounds
Carbon compounds may be organic, organometallic, or inorganic.
- Organic compounds: Organic compounds always contain carbon and hydrogen. Major classes of organic compounds include proteins, lipids, carbohydrates, and nucleic acids. Traditionally, organic compounds occur in living organisms, but it’s also possible to synthesize them in the lab.
- Organometallic compounds: Organometallic compounds contain at least one carbon-metal bond. Examples include ferrocene, tetraethyl lead, and Zeise’s salt.
- Inorganic carbon compounds: Inorganic compounds contain carbon, but not hydrogen. Inorganic compounds occur in minerals and gases. Examples include carbon monoxide (CO), carbon dioxide (CO2), and calcium carbonate (CaCO3).
Some compounds defy the simple definitions. For example, hydrogen cyanide (HCN) is considered an inorganic compound. Even though it contains hydrogen and is produced by some living organisms, the bond between hydrogen and the cyanide group is more ionic in nature than covalent. Another exception is phosgene (COCl2), which contains doesn’t contain hydrogen yet is organic. Partially the explanation is because phosgene comes from chlorinated hydrocarbon (organic compounds) and partially it’s organic due to the nature of the chemical bonding of the carbon atom.
Allotropes are different forms of a pure element. Here, carbon atoms bond with other carbon atoms. Allotropes are inorganic compounds. Here is a list of some carbon allotropes:
- Amorphous carbon
- Carbon nanotubules
- Carbon nanofoam
- Glassy carbon
- Lonsdaleite (hexagonal carbon)
- Linear acetylenic carbon
- Diatomic carbon
Several alloys contain carbon. Carbon alloys include steel and cast iron. Even “pure” metals are partially carbon alloys, if they are smelted using coke. Examples include zinc, aluminum, and chromium.
Types of Chemical Bonds in Carbon Compounds
Carbon usually forms covalent chemical bonds with itself and other types of atoms. Nonpolar covalent bonds form when carbon bonds to other carbon atoms. Polar covalent bonds form when carbon bonds to nonmetals or metalloids.
Carbon forms ionic bonds when it bonds to metals. For example, the chemical bond between carbon and calcium in calcium carbide (CaC2) is ionic in nature.
The carbon-carbon bonds within graphene involve delocalized electrons and are metallic bonds.
Number of Chemical Bonds Involving Carbon Atoms
The number of bonds carbon atoms form with other elements depend on its oxidation state. The most common oxidation state is +4 or -4 (tetravalent), so carbon usually forms four bonds. However, other carbon oxidation states include +3, +2, +1, 0, -1, -2, and -3. In a few cases, carbon even forms six bonds with other atoms. For example, the hexamethylbenzene (C12H18) structure includes a single carbon atom bonded to six other carbon atoms!
Naming Carbon Compounds
The names of some types of carbon compounds indicate their chemical composition:
- Carbides: Carbides are binary compounds of carbon with another element that has a lower electronegativity. Al4C3, CaC2, SiC, TiC, and WC are examples of carbides.
- Carboranes: Carboranes are molecular clusters of carbon and boron, often with hydrogen. An example of a carborane is H2C2B10H10.
- Carbon halides: Carbon halides contain carbon and a halogen. Examples of carbon halides include carbon tetraiodide (CI4) and carbon tetrachloride (CCl4).
Properties of Carbon Compounds
Carbon compounds encompass a diverse group of chemicals, but they share common characteristics:
- A key property of carbon is catenation or the ability to forms chains and rings. So, many carbon compounds contain rings or long chains or form polymers.
- Most carbon compounds have low reactivity at room temperature, but vigorously react when heated. For example, fuels are stable until heated.
- Many carbon compounds are combustible.
- Many carbon compounds are nonpolar. Because they are nonpolar, they often have low solubility in water. This is why water alone doesn’t cut oil or grease.
- Compounds of carbon with nitrogen are often explosive. The bond between the atoms is unstable and releases considerable energy when broken.
- Compounds of carbon and nitrogen often have a distinct, unpleasant odor as liquids. Usually solids are odorless.
Uses of Carbon Compounds
Any application you can name uses carbon compounds. All living organisms contain carbon. Fuels and foods are carbon-based. Plastics, pigments, pesticides, and many alloys are carbon compounds.
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