( ( Left ( on ( their own ) ) ) ( , ( ( ( the electrons ) ( of ( an atom ) ) ) ( ( tend ( to ( relax ( into ( orbitals ( that ( ( ( leave ( ( the atom ) ( with ( the ( lowest ( possible energy ) ) ) ) ) ) -- ) ( its ( ground state ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (S (VP (VBN Left) (PP (IN on) (NP (PRP$ their) (JJ own))))) (, ,) (NP (NP (DT the) (NNS electrons)) (PP (IN of) (NP (DT an) (NN atom)))) (VP (VBP tend) (S (VP (TO to) (VP (VB relax) (PP (IN into) (NP (NP (NNS orbitals)) (SBAR (WHNP (WDT that)) (S (VP (VBP leave) (NP (NP (DT the) (NN atom)) (PP (IN with) (NP (DT the) (JJS lowest) (JJ possible) (NN energy)))) (: --) (NP (PRP$ its) (NN ground) (NN state))))))))))) (. .)))
Left on their own, the electrons of an atom tend to relax into orbitals that leave the atom with the lowest possible energy--its ground state.
(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)))))) (. .)))