( ( The ( outer electrons ) ) ( ( are ( known ( as ( Valence electrons ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ outer) (NNS electrons)) (VP (VBP are) (VP (VBN known) (PP (IN as) (NP (NNP Valence) (NNS electrons))))) (. .)))
The outer electrons are known as 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)))) (. .)))