Carbon and the Molecular Diversity of Life

What is organic chemistry?

Organic chemistry is the branch of chemistry that specializes in the study of carbon compounds. For historical reasons, compounds containing carbon are said to be organic. Organic compounds range from simple molecules (ex. Methane – CH4), to more complex ones, such as proteins (thousands of atoms). The basis of organic chemistry is the unique chemical versatility of carbon.

How does the electron configuration of carbon determine its covalent compatibility with many different elements?

Carbon has 6 electrons. 4 of these are its valence electrons in the valence shell. Having 4 valence electrons in a shell that holds 8, carbon would have to donate or accept 4 electrons to complete its valence shell and become an ion.

Instead, a carbon atom usually completes its valence shell by sharing his 4 electrons with other atoms by covalent bonds. Bonds can be single or double.

What are isomers and how do we classify them?

Isomers are compounds that have the same numbers of atoms of the same element but different structures and hence different properties.

Three types of isomers are:

structural isomers

differ in the covalent partners (arrangements of their atoms)

geometric isomers

differ in their spatial arrangements (same covalent partnerships)

enantiomers

differ in spatial arrangement around an asymmetric carbon (“mirror” images of each other)

Facts

Living matter is made mostly of carbon, oxygen, hydrogen and nitrogen, with some sulfur and phosphorus.

The foundation of organic chemistry is not some intangible life force, but the unique chemical versatility of the element carbon.

Carbon has 6 electrons, with 2 in the first shell and 4 in the valence shell (tetravalence)

Hydrocarbons (look in key terms) can undergo reactions that release a relatively large amount of energy.

Hydrocarbons consist only of carbon and hydrogen.

Key terms:

Organic Chemistry = branch of chemistry that specializes in the study of carbon compounds

Vitalism = the belief in a life force outside the jurisdiction of physical and chemical laws

Mechanism = the view that physical and chemical laws govern all natural phenomena, including the process of life

Tetravalence = ability of the molecule to branch off in as many as four directions

Hydrocarbons = Organic molecules made of only carbon and hydrogen

Isomers = Compounds with the same molecular formula but have different structures

Enantiomers = molecules that are mirror images of each other.

Functional groups = A group of atoms attached to a carbon skeleton

ATP = adenosine triphosphate, an important source of energy

ADP = adenosine diphosphate, product of losing one phosphate from ATP

Summary:

Of all chemical elements, carbon is unparalleled in its ability to form molecules that are large, complex and diverse, and this molecular diversity has made possible the diversity of organisms that have evolved on Earth. The study of carbon compounds is called organic chemistry (see more in next chapter). Carbon has 6 electrons and 4 of them are in the valence shell and it can easily accept or give 4 other electrons, making covalent bonds with other atoms. Some of the examples for the molecular diversity arising from carbon skeleton variations are isomers (take a look up on the page). Furthermore, functional groups, important chemical groups attach to carbon skeletons, making important biological molecules.

Extra:

Stanley Miller experiment (video)