( ( When ( ( ionic compounds ) ( are ( subjected ( to ( distortion ( ( cation-cation ( and ( anion-anion repulsions ) ) ) ( between ( layers ( of ions ) ) ) ) ) ) ) ) ) ) ( ( ( cause brittle ) cleavage ) . ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (JJ ionic) (NNS compounds)) (VP (VBP are) (VP (VBN subjected) (S (VP (TO to) (VP (VB distortion) (NP (NP (JJ cation-cation) (CC and) (JJ anion-anion) (NNS repulsions)) (PP (IN between) (NP (NP (NNS layers)) (PP (IN of) (NP (NNS ions))))))))))))) (VP (VBP cause) (ADJP (JJ brittle)) (S (ADJP (JJ cleavage)))) (. .)))
When ionic compounds are subjected to distortion cation-cation and anion-anion repulsions between layers of ions cause brittle cleavage .
(ROOT (S (SBAR (WHADVP (WRB When)) (S (VP (VBG naming) (NP (DT an) (JJ ionic) (NN compound))))) (, ,) (NP (DT the) (NN cation)) (VP (VBZ is) (VP (VBN written) (ADVP (RB first)))) (. .)))
When naming an ionic compound, the cation is written first.