( ( Due ( to ( ( the ( lattice spacing ) ) ( of ( ( ( the atoms ) and ) ( other ( relevant factors ) ) ) ) ) ) ) ( , ( there ( ( is ( ( an ( energy gap ) ) ( between ( ( ( the highest ) - ) ( ( ( energy ( electron ( valence level ) ) ) and ) ( the ( lowest-energy ( conduction level ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (JJ Due) (TO to) (NP (NP (DT the) (NN lattice) (NN spacing)) (PP (IN of) (NP (NP (DT the) (NNS atoms)) (CC and) (NP (JJ other) (JJ relevant) (NNS factors)))))) (, ,) (NP (EX there)) (VP (VBZ is) (NP (NP (DT an) (NN energy) (NN gap)) (PP (IN between) (NP (NP (DT the) (JJS highest)) (: -) (NP (NP (NN energy) (NN electron) (NN valence) (NN level)) (CC and) (NP (DT the) (JJ lowest-energy) (NN conduction) (NN level))))))) (. .)))
Due to the lattice spacing of the atoms and other relevant factors, there is an energy gap between the highest- energy electron valence level and the lowest-energy conduction level.
(ROOT (S (NP (NP (NNS Electrons)) (PP (IN in) (NP (NP (DT the) (JJ outer) (NN energy) (NN level)) (PP (IN of) (NP (DT an) (NN atom)))))) (VP (VBP are) (VP (VBN called) (NP (JJ valence) (NNS electrons)))) (. .)))