( ( ( Carbon 's ) ( four valence ) ) ( ( ( electrons then ) ( half-fill ( each ( of ( the ( four orbitals ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Carbon) (POS 's)) (CD four) (NN valence)) (VP (VBZ electrons) (RB then) (VP (VB half-fill) (NP (NP (DT each)) (PP (IN of) (NP (DT the) (CD four) (NNS orbitals)))))) (. .)))
Carbon's four valence electrons then half-fill each of the four orbitals.
(ROOT (S (NP (CD Four) (JJ valence) (NNS electrons)) (VP (MD can) (VP (VB be) (VP (VBN found) (PP (IN in) (NP (DT a) (NN carbon) (NN atom)))))) (. .)))