Here's why:

* Carbon's electron configuration: Carbon has 4 valence electrons (2s² 2p²).

* Bonding: In methane, carbon forms four single covalent bonds with four hydrogen atoms.

* Hybridization: To form these four bonds, carbon undergoes sp3 hybridization. This means one 2s orbital and three 2p orbitals combine to form four equivalent sp3 hybrid orbitals.

* Shape: The four sp3 hybrid orbitals are arranged in a tetrahedral geometry, which explains the shape of methane.

Let me know if you'd like more details about the process of hybridization!