( ( ( The number ) ( of ( neutrons ( in ( an atom ) ) ) ) ) ( ( ( ( ( can vary ) , ) but ) ( ( is typically ) ( close ( ( ( to ( ( the number ) ( of protons ) ) ) , ) ( for ( ( light elements ) ( -LRB- ( ( atoms ( with ( ( small numbers ) ( of protons ) ) ) ) -RRB- ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN number)) (PP (IN of) (NP (NP (NNS neutrons)) (PP (IN in) (NP (DT an) (NN atom)))))) (VP (VP (MD can) (VP (VB vary))) (, ,) (CC but) (VP (VBZ is) (ADVP (RB typically)) (ADJP (JJ close) (PP (PP (TO to) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NNS protons))))) (, ,) (PP (IN for) (NP (NP (JJ light) (NNS elements)) (PRN (-LRB- -LRB-) (NP (NP (NNS atoms)) (PP (IN with) (NP (NP (JJ small) (NNS numbers)) (PP (IN of) (NP (NNS protons)))))) (-RRB- -RRB-)))))))) (. .)))
The number of neutrons in an atom can vary, but is typically close to the number of protons, for light elements (atoms with small numbers of protons).
(ROOT (S (S (NP (PRP You)) (VP (VBP call) (NP (NP (DT a) (NN substance)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (RB not) (VP (VB be) (VP (VBN separated) (PP (IN into) (NP (NP (JJR smaller) (NNS pieces)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (ADVP (RB also)) (VP (VBN defined) (PP (IN by) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NNS protons))))))))))))))))))) (NP (PRP it)) (VP (VP (VBZ has)) (, ,) (NP (DT a) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN element))) (. .)))