( ( Explain ( the ( octet rule ) ) ) . )
(ROOT (S (VP (VB Explain) (NP (DT the) (JJ octet) (NN rule))) (. .)))
Explain the octet rule.
(ROOT (S (NP (DT The) (NN octet) (NN rule)) (VP (VP (VBZ is) (NP (NP (DT a) (NN result)) (PP (IN of) (NP (NP (NNS trends)) (PP (IN in) (NP (NNS energies))))))) (CC and) (VP (VBZ is) (ADJP (JJ useful) (PP (IN in) (S (VP (VBG explaining) (SBAR (WHADVP (WRB why)) (S (NP (NNS atoms)) (VP (VBP form) (NP (DT the) (NNS ions)) (SBAR (IN that) (S (NP (PRP they)) (VP (VBP do))))))))))))) (. .)))