( ( ( An introduction ) ( to ( ( ( ( ( ( ( ( ( ( atoms and ) elements ) , ) compounds ) , ) ( atomic ( ( structure and ) bonding ) ) ) , ) ( the molecule ) ) and ) ( chemical reactions ) ) ) ) . )
(ROOT (NP (NP (DT An) (NN introduction)) (PP (TO to) (NP (NP (NNS atoms) (CC and) (NNS elements)) (, ,) (NP (NNS compounds)) (, ,) (NP (JJ atomic) (NN structure) (CC and) (NN bonding)) (, ,) (NP (DT the) (NN molecule)) (CC and) (NP (NN chemical) (NNS reactions)))) (. .)))
An introduction to atoms and elements, compounds, atomic structure and bonding, the molecule and chemical reactions.
(ROOT (S (ADVP (RB Replace)) (NP (NP (DT another)) (PP (IN in) (NP (DT a) (NN molecule)))) (VP (VBZ happens) (PP (TO to) (NP (NNS atoms))) (PP (IN during) (NP (DT a) (NN substitution) (NN reaction)))) (. .)))
Replace another in a molecule happens to atoms during a substitution reaction.