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Animation of the bonding in a methane molecule (CH4). Initially a carbon atom has four electron orbitals, an inner spherical 1s shell, a spherical 2s shell, and two bi-lobed 2p shells. It might be expected that only the 2p orbitals would be involved in bonding, producing CH2, but instead one of the 2s electrons rises to a vacant 2p level (dark red), and the three 2p orbitals and the 2s orbital hybridise, producing four identical sp3 orbitals, arranged in a tetrahedral shape. These then bond with hydrogen atoms, with a release of energy. The hybridised CH4 is energetically favoured over CH2 as the energy required to raise the 2s electron to the 2p level is more than made up for by the creation of the two extra C-H bonds that the hybridisation permits.
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