Give the general formula of the alkane series and discuss the structure of methane.

(N/A) The general formula for alkanes is $C_{n}H_{2n+2}$, where $n$ is the number of carbon atoms and $(2n+2)$ is the number of hydrogen atoms in the molecule. For example, butane has $4$ carbon atoms and $10$ hydrogen atoms, so its formula is $C_{4}H_{10}$.
Bonding and structure: Methane has a tetrahedral structure. The carbon atom lies at the center, and the four hydrogen atoms lie at the four corners of a regular tetrahedron.
$(i)$ In methane, the $H-C-H$ bond angle is $109.5^{\circ}$.
(ii) In methane, the $C-H$ bond length is $112 \text{ pm}$.
(iii) The $C-H$ bonds are formed by the head-on overlapping of $sp^{3}$ hybrid orbitals of carbon and $1s$ orbitals of hydrogen atoms.
In alkanes, tetrahedra are joined together where $C-C$ and $C-H$ bond lengths are $154 \text{ pm}$ and $112 \text{ pm}$ respectively. All these are sigma $(\sigma)$ bonds. The $C-C$ sigma bond is formed by $sp^{3}-sp^{3}$ overlap, and the $C-H$ sigma bond is formed by $sp^{3}-1s$ overlap.