( ( ( An atom ) ( with ( ( more ( than four ) ) ( but ( ( less ( than eight ) ) ( valence electrons ) ) ) ) ) ) ( ( is unstable ) . ) )
(ROOT (S (NP (NP (DT An) (NN atom)) (PP (IN with) (NP (NP (QP (JJR more) (IN than) (CD four))) (PP (CC but) (NP (QP (JJR less) (IN than) (CD eight)) (JJ valence) (NNS electrons)))))) (VP (VBZ is) (ADJP (JJ unstable))) (. .)))
An atom with more than four but less than eight valence electrons is unstable.
(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)))))) (. .)))