( ( ( An atom ) ( of carbon ) ) ( ( has ( ( ( six protons ) and ) ( six neutrons ) ) ) . ) )
(ROOT (S (NP (NP (DT An) (NN atom)) (PP (IN of) (NP (NN carbon)))) (VP (VBZ has) (NP (NP (CD six) (NNS protons)) (CC and) (NP (CD six) (NNS neutrons)))) (. .)))
An atom of carbon has six protons and six neutrons.
(ROOT (S (NP (DT All) (NN carbon) (NNS atoms)) (VP (VBP have) (NP (CD six) (NNS protons))) (. .)))