( ( four ( valence electrons ) ) ( ( are ( shared ( between ( two atoms ) ) ) ) . ) )
(ROOT (S (NP (CD four) (JJ valence) (NNS electrons)) (VP (VBP are) (VP (VBN shared) (PP (IN between) (NP (CD two) (NNS atoms))))) (. .)))
four valence electrons are shared between two atoms.
(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)))))) (. .)))