( ( ( Describe and ) ( discuss ( ( ( ( ( the ( energy levels ) ) ( -LRB- ( ( electron shells ) -RRB- ) ) ) ( of ( an atom ) ) ) , ) ( including ( ( the orbitals ) ( of ( the ( first ( two levels ) ) ) ) ) ) ) ) ) . )
(ROOT (S (VP (VP (VB Describe)) (CC and) (VP (VB discuss) (NP (NP (NP (DT the) (NN energy) (NNS levels)) (PRN (-LRB- -LRB-) (NP (NN electron) (NNS shells)) (-RRB- -RRB-))) (PP (IN of) (NP (DT an) (NN atom))) (, ,) (PP (VBG including) (NP (NP (DT the) (NNS orbitals)) (PP (IN of) (NP (DT the) (JJ first) (CD two) (NNS levels)))))))) (. .)))
Describe and discuss the energy levels (electron shells) of an atom, including the orbitals of the first two levels.
(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)))))) (. .)))