( ( Electrons ( in ( the ( outer ( energy level ) ) ) ) ) ( ( can ( be ( called ( valence electrons ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Electrons)) (PP (IN in) (NP (DT the) (JJ outer) (NN energy) (NN level)))) (VP (MD can) (VP (VB be) (VP (VBN called) (NP (JJ valence) (NNS electrons))))) (. .)))
Electrons in the outer energy level can be called valence electrons .
(ROOT (S (NP (NP (NNS Electrons)) (PP (IN in) (NP (NP (DT the) (JJ outer) (NN energy) (NN level)) (PP (IN of) (NP (DT an) (NN atom)))))) (VP (VBP are) (VP (VBN called) (NP (JJ valence) (NNS electrons)))) (. .)))