( ( ( ( ( ( valence ( level energy ) ) , ) ( bound state ) ) -- ) ( ( Energy content ) ( of ( ( an electron ) ( in ( orbit ( about ( an ( atomic nucleus ) ) ) ) ) ) ) ) ) . )
(ROOT (NP (NP (NP (JJ valence) (NN level) (NN energy)) (, ,) (VP (VBN bound) (NP (NN state)))) (: --) (NP (NP (NNP Energy) (NN content)) (PP (IN of) (NP (NP (DT an) (NN electron)) (PP (IN in) (NP (NP (NN orbit)) (PP (IN about) (NP (DT an) (JJ atomic) (NN nucleus)))))))) (. .)))
valence level energy, bound state--Energy content of an electron in orbit about an atomic nucleus.
(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)))) (. .)))