The alkanes are a family of saturated hydrocarbons. This means that they have no double or triple bonds between the carbon atoms. The general formula for Alkanes is C_nH_2n+2 and the alkanes can occur as both straight and branched – chain molecules.
Eg: Methane, Ethane, 2–methylbutane etc.

Methane:
Methane is the simplest hydrocarbon. It(CH₄) occurs as a natural gas in the underground petroleum wells deep inside the earth. Methane gas is also known as marsh gas as it is emitted by bacterial decomposition of dead plants and animals. Methane is found in coal mine gases, gobar gas, sewage gas and bio–gas.

Structure of Methane:
The valency of carbon is four and the valency of hydrogen is one. So, one carbon atom combines with four hydrogen atoms to form methane with four equivalent C–H bonds. Carbon atom undergoes sp³ hybridization in methane. In this type of hybridization (sp³ hybridization), the s and p orbitals mix to form four identical new orbitals known as sp³ hybrid orbitals. In carbon, each of these orbitals contains a single electron, which can then form a single bond. Overlap between each of the four sp³ orbitals with the 1s orbital of a hydrogen atom produces the methane molecule. Due to electrostatic repulsion between the electron pairs, the sp³ orbitals are oriented tetrahedrally. The C–H bond length is 1.54Å and bond angle between two C–H bonds is 109°5'.

Ethane:
Ethane is the second most homologue of methane. Ethane is a colorless odorless gas.
Structure of Ethane:
Ethane molecule consists of two carbon atoms and six H–atoms with a molecular formula of C₂H₆. In ethane, each carbon atom is sp³–hybridized and has four sp³–hybrid orbitals. One s–orbital and three p–orbitals (p_x, p_y, p_z) undergo Sp³–hybridization to produce four sp³–hybrid orbitals for each carbon atom. Out of four, three sp³–hybrid orbitals one sp³–hybrid orbital of one carbon atom overlaps with one s–orbital of three hydrogen atoms to produce three sigma bonds and the last overlaps with one sp³–orbital of other carbon atom to produce a sigma bond between two carbon atoms. Ethane molecule is arranged in tetrahedral geometry in which central carbon atoms are surrounded by hydrogen atoms in three dimensions. H–C–H bond angle is 109° 28', C–H bond length is 1.09Å and C–C bond length is 1.54Å.

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