( ( Chemical ( ( compounds and ) ( chemical bonds ) ) ) . )
(ROOT (NP (NP (NNP Chemical)) (NP (NP (NNS compounds)) (CC and) (NP (NN chemical) (NNS bonds))) (. .)))
Chemical compounds and chemical bonds.
(ROOT (S (NP (NP (DT The) (NNS atoms)) (PP (IN of) (NP (DT a) (NN compound)))) (VP (VBP are) (VP (VBN held) (ADVP (RB together)) (PP (IN by) (NP (NN chemical) (NNS bonds))))) (. .)))