( ( Electron deficiency ) ( ( occurs ( when ( ( a compound ) ( has ( ( ( too few ) ( valence electrons ) ) ( for ( ( the connections ) ( between ( atoms ( to ( be ( described ( as ( covalent bonds ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Electron) (NN deficiency)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (NN compound)) (VP (VBZ has) (NP (NP (ADJP (RB too) (JJ few)) (NN valence) (NNS electrons)) (PP (IN for) (NP (NP (DT the) (NNS connections)) (PP (IN between) (NP (NNS atoms) (S (VP (TO to) (VP (VB be) (VP (VBN described) (PP (IN as) (NP (JJ covalent) (NNS bonds)))))))))))))))) (. .)))
Electron deficiency occurs when a compound has too few valence electrons for the connections between atoms to be described as covalent bonds.
(ROOT (S (NP (DT A) (NN covalent) (NN network)) (ADVP (RB solid)) (VP (VBZ is) (NP (NP (DT a) (NN compound)) (SBAR (WHPP (IN in) (WHNP (WDT which))) (S (NP (NP (DT all)) (PP (IN of) (NP (DT the) (NNS atoms)))) (VP (VBP are) (VP (VBN connected) (PP (TO to) (NP (CD one) (DT another))) (PP (IN by) (NP (JJ covalent) (NNS bonds))))))))) (. .)))