( ( Electrons ( in ( ( the ( outer shell ) ) ( of ( the atom ) ) ) ) ) ( ( are ( called ( valence electrons ) ) ) . ) )
(ROOT (S (NP (NP (NNS Electrons)) (PP (IN in) (NP (NP (DT the) (JJ outer) (NN shell)) (PP (IN of) (NP (DT the) (NN atom)))))) (VP (VBP are) (VP (VBN called) (NP (JJ valence) (NNS electrons)))) (. .)))
Electrons in the outer shell of the atom are 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)))) (. .)))