Describe the shapes of carbon compounds and the effects of hybridization of carbon atoms.

(N/A) The knowledge of fundamental concepts of molecular structure helps in understanding and predicting the properties of organic compounds.
The tetravalence of carbon and the formation of covalent bonds are explained in terms of its electronic configuration and the hybridization of $s$ and $p$-orbitals.

Property	$CH_4$ (Methane)	$C_2H_6$ (Ethane)	$C_2H_4$ (Ethene)	$C_2H_2$ (Ethyne)
Hybridization	$sp^3$	$sp^3$	$sp^2$	$sp$
Shape	Tetrahedral	Tetrahedral	Trigonal planar	Linear
Bond angle	$109.5^{\circ}$	$109.5^{\circ}$	$120^{\circ}$	$180^{\circ}$
$s$-character	$25\%$	$25\%$	$33.3\%$	$50\%$

As the $s$-character increases $(sp^3$ $\rightarrow sp^2$ $\rightarrow sp)$:
$1$. Electronegativity of carbon increases.
$2$. Bond length between carbon atoms decreases.
$3$. Bond enthalpy (strength) increases.