The carbon atoms in alkanes are described as sp3 hybrids; that is to say that, to a good approximation, the valence electrons are in orbitals directed towards the corners of a tetrahedron which are derived from the combination of the 2s orbital and the three 2p orbitals.
ðə kˈɑːɹbən ˈæɾəmz ɪn ˈælkeɪnz ɑːɹ dᵻskɹˈaɪbd æz ˌɛspˈiː θɹˈiː hˈaɪbɹɪdz; ðæt ɪz tə sˈeɪ ðˈæt, tʊ ɐ ɡˈʊd ɐpɹˌɑːksɪmˈeɪʃən, ðə vˈeɪləns ᵻlˈɛktɹɑːnz ɑːɹ ɪn ˈɔːɹbɪɾəlz dᵻɹˈɛktᵻd təwˈɔːɹdz ðə kˈɔːɹnɚz əvə tˌɛtɹɐhˈiːdɹən wˌɪtʃ ɑːɹ dᵻɹˈaɪvd fɹʌmðə kˌɑːmbᵻnˈeɪʃən ʌvðə tˈuː z ˈɔːɹbɪɾəl ænd ðə θɹˈiː tˈuː pˈiː ˈɔːɹbɪɾəlz.