HYDROCARBON

Question: Why do carbon atoms form bonds not only one but also can form a double bond or triple bond?

CARBON

 One of the privileges of carbon that is not owned by the other elements is their ability to form chains of carbon atoms, which we hereafter refer to as the carbon chain.

Carbon chains may be either a single bond, double bond, or a triple bond. Forms of carbon chains themselves are very varied, there is a straight (unbranched), there is a branching, there are open, and there is a closed (circular). Various forms of carbon chains presented in the figure below.

Compounds with an open chain compounds called aliphatic compounds while closed or circular chain called cyclic compounds. The compounds are all carbon bond is a single bond, - C - C - called unsaturated carbon compounds, while having a carbon-carbon double bond, - C - C -, or triple - C = C -, called unsaturated carbon compounds.

Cyclic compounds having conjugated bonds, the carbon-carbon bond alternating single and dual, are called aromatic compounds. All cyclic compounds that are not included aromatic compounds are called alicyclic compounds, (the word comes from the word ali alicyclic and cyclic). These compounds are called alicyclic compound because it has a circular shape, but its properties resemble aliphatic compounds.


Why carbon can form so many compounds, with very varied types? Why is this not happening in the adjacent element or elements are classified with the carbon in the periodic table? BC has the electron configuration of atoms 2 4. The four valence electrons distributed on the four C atoms in a symmetrical position.

The ability to bind carbon atoms and follow the octet rule is different from other atoms, even within a single class. For example, boron and nitrogen atoms. Electron configuration of two atoms is J3: 2 3 and _n: 2 5. Boron atom has three valence electrons so that when the covalent bonds, resulting compounds do not follow the octet Kaidan. Note the Lewis structure of the compound following BH3!

The compound BH, has the form of a symmetrical molecule and has three covalent bonds. In contrast to compound BH3, NH3 compounds follow the octet rule, but the shape of the molecule is not symmetrical because there is a lone pair.


Thus, compounds BH, and NH3 only has three covalent bonds. What about silicon? The silicon atom has an electron configuration 2 8 4. The silicon atom has four valence electrons with the carbon atom. The four electrons in the silicon atom is distributed on four sides symmetrically. Consider the Lewis structure of the following compound?


Note the Lewis structure and bonding in compounds SiH4 and SiO,. Lewis Structure and bonding in compounds such as CH4 and CO,. So, what are the differences?
Valence electrons in a silicon atom is located on the third skin, while the valence electrons in the carbon atom located on a second skin. Thus the Si atom radius greater than the radius of the atom C. Thus, the bonding Si - H to the compound anyway ^ weaker than the C - H in the compound CH4.

The carbon atom has four valence electrons with the atomic radii price the smallest of the atomic radius of other elements in the group IVA. It facilitates the C atom to form covalent bonds with other atoms, especially with atomic H, O, N, and halogen atoms (F, Cl, Br, and I). Covalent bonds are formed to meet the octet rule. The carbon atom can form up to four covalent bonds. Covalent bond formed by atoms C is more powerful than other covalent bonds, so that the carbon compounds are stable.

The position of carbon atoms in the periodic table in the middle so it has a moderate electronegativity value (2.5). This trait causes the carbon atoms can bind atoms having electronegativity greater or even smaller. The carbon atom can have a positive oxidation state (+2, +4), negative (-2, -4), or even zero.