The structures of most organic molecules are more complicated than those of most inorganic ones.

A short look at carbon's atomic characteristics and bonding behavior explains why. Electron configuration, electronegativity, and bonding are all terms used to describe electrons.

Carbon creates covalent bonds rather than ionic bonds in all of its elemental and chemical forms. This bonding characteristic is caused by the electron configuration and electronegativity of carbon:

Carbon's ground-state electron configuration of [He] 2s 2 2p2 — four more electrons than He and four less than Ne — makes the production of carbon ions energetically impossible under normal conditions.

The sum of IE1 through IE4 (>14,000 kJ/mol!) is required for the loss of four e to create the C4+ cation; the sum of EA1 through EA4, the latter three stages of which are endothermic, is required for the gain of four e to form the C4 anion.

Carbon, located in Period 2, has an electronegativity (EN = 2.5) that is halfway between that of the most metallic element (Li, EN = 1.0) and that of the most nonmetallic active element (F, EN = 4.0).

Catenation, bond characteristics, and molecule structure are all factors to consider. Carbon has the characteristic of catenation, which allows it to bind to one or more other carbon atoms, resulting in a plethora of chemically and thermally stable chain, ring, and branching compounds:

Carbon forms four bonds in virtually all of its compounds, and they point in as many as four different directions, thanks to the process of orbital hybridization (Section 11.1).

Because carbon's small size allows close proximity to another atom and thus greater orbital overlap, carbon forms relatively short, strong bonds.

The CC bond is short enough to allow for a side-to-side overlap of half-filled, unhybridized p orbitals as well as the creation of numerous bonds. These prevent connected groups from rotating (see Figure 11.14), resulting in extra structures.

The stability of the molecules. Although silicon and many other elements catenate, none of them produce chains as stable as carbons. Carbon chains are extremely stable and common because of atomic and bonding properties:

Atomic size and binding strength are two factors to consider. Bonds between similar atoms become longer and weaker as atomic size decreases in Group 4A(14). As a result, a CC bond (347 kJ/mol) is far stronger than a SiSi bond (226 kJ/mol).

Organic molecules are notable for their vast quantity and varied chemical behavior, in addition to their intricate structures.

Several million organic molecules have been discovered or synthesized, and thousands more are found or synthesized each year.

This variety is likewise based on atomic behavior and is caused by three interconnected factors: bonding to heteroatoms, reactivity differences, and the presence of functional groups.

The structural complexity of organic molecules is due to carbon's small size, intermediate electronegativity, four valence electrons, and capacity to form numerous bonds. These variables contribute to carbon's capacity to catenate, which results in the formation of chains, branches, and rings of C atoms.

Small size and the lack of d orbitals at the valence level result in strong, chemically resistant connections pointing in up to four directions from each C. Carbon's propensity to bind to many other elements, particularly O and N, results in polar, reactive bonds, which contribute to the chemical variety of organic molecules.

Most organic compounds have functional groups, which are particular combinations of bound atoms that respond in a certain way.

Dehydration-condensation processes produce the three forms of natural polymers: polysaccharides, proteins, and nucleic acids.

Polysaccharides are made up of cyclic monosaccharides like glucose. Cellulose, starch, and glycogen all provide structural or energy-storage functions. Proteins are polyamides made up of up to 20 distinct kinds of amino acids.

Fibrous proteins have elongated forms and provide structural functions. Globular proteins are small proteins that perform metabolic, immunologic, and hormonal functions. A protein's structure and function are determined by its amino acid sequence. Nucleic acids (DNA and RNA) are polynucleotides made up of four kinds of mononucleotides.

Nucleic acids (DNA and RNA) are polynucleotides made up of four kinds of mononucleotides. The sequence of amino acids in an organism's proteins is determined by the base sequence of the DNA chain. Protein synthesis and DNA replication rely on hydrogen bonding between particular base pairs.

DNA sequencing is a technique for determining the identity and order of nucleotides in a DNA chain fragment. DNA fingerprinting is a technique that uses the unique sequence of bases in a person's DNA to identify him or her.