( ( ( ( ( ( All ( of ( ( the atoms ) ( of ( a ( particular element ) ) ) ) ) ) ( have ( the ( same ( atomic number ) ) ) ) ) , ) but ) ( they ( can ( have ( ( different numbers ) ( of ( neutrons ( -LRB- ( i.e. ( , ( ( different ( mass numbers ) ) -RRB- ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NP (DT All)) (PP (IN of) (NP (NP (DT the) (NNS atoms)) (PP (IN of) (NP (DT a) (JJ particular) (NN element)))))) (VP (VBP have) (NP (DT the) (JJ same) (JJ atomic) (NN number)))) (, ,) (CC but) (S (NP (PRP they)) (VP (MD can) (VP (VB have) (NP (NP (JJ different) (NNS numbers)) (PP (IN of) (NP (NP (NNS neutrons)) (PRN (-LRB- -LRB-) (FW i.e.) (, ,) (ADJP (JJ different) (PP (IN mass) (NP (NNS numbers)))) (-RRB- -RRB-)))))))) (. .)))
All of the atoms of a particular element have the same atomic number, but they can have different numbers of neutrons (i.e., different mass numbers).
(ROOT (S (NP (NP (DT The) (NN number)) (PP (IN of) (NP (NNS neutrons)))) (VP (MD can) (VP (VB vary) (PP (IN between) (NP (NP (NNS atoms)) (PP (IN of) (NP (DT the) (JJ same) (NN element))))))) (. .)))