( Electrons ( ( can ( be ( ( raised ( to ( higher-energy orbitals ) ) ) ( when ( ( an atom ) ( absorbs energy ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Electrons)) (VP (MD can) (VP (VB be) (VP (VBN raised) (PP (TO to) (NP (JJ higher-energy) (NNS orbitals))) (SBAR (WHADVP (WRB when)) (S (NP (DT an) (NN atom)) (VP (VBZ absorbs) (NP (NN energy)))))))) (. .)))
Electrons can be raised to higher-energy orbitals when an atom absorbs energy.
(ROOT (S (NP (NP (NNS Electrons)) (PP (IN in) (NP (NP (JJ successive) (NNS atoms)) (PP (IN on) (NP (DT the) (JJ periodic) (NN table)))))) (VP (VBP tend) (S (VP (TO to) (VP (VB fill) (NP (JJ low-energy) (NNS orbitals)) (ADVP (RB first)))))) (. .)))