( ( ( ( Rule ( 3b ( -RRB- applies ) ) ) ( to ( the energy ) ) ) ( ordering ( of ( the ( I atom ) ) ) ) ) . )
(ROOT (NP (NP (NP (NNP Rule) (NNP 3b) (-RRB- -RRB-) (NNP applies)) (PP (TO to) (NP (DT the) (NN energy)))) (VP (VBG ordering) (PP (IN of) (NP (DT the) (NN I) (NN atom)))) (. .)))
Rule 3b) applies to the energy ordering of the I atom.
(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))))))))))))) (. .)))