▁ox al ate , ▁. ▁ ▁There ▁is ▁however ▁a ▁large ▁number ▁of ▁stable ▁an ions ▁in ▁this ▁class , ▁including ▁several ▁ones ▁that ▁have ▁research ▁or ▁industrial ▁use . ▁ ▁There ▁are ▁also ▁many ▁un stable ▁an ions , ▁like ▁ ▁and ▁, ▁that ▁have ▁a ▁fle eting ▁existence ▁during ▁some ▁chemical ▁re actions ; ▁and ▁many ▁hypoth et ical ▁species , ▁like ▁, ▁that ▁have ▁been ▁the ▁subject ▁of ▁theoretical ▁studies ▁but ▁have ▁yet ▁to ▁be ▁observed . ▁ ▁St able ▁ox oc ar bon ▁an ions ▁form ▁sal ts ▁with ▁a ▁large ▁variety ▁of ▁c ations . ▁ ▁Un stable ▁an ions ▁may ▁persist ▁in ▁very ▁ra ref ied ▁g ase ous ▁state , ▁such ▁as ▁in ▁inter stell ar ▁clouds . ▁ ▁Most ▁ox oc ar bon ▁an ions ▁have ▁corresponding ▁mo iet ies ▁in ▁organ ic ▁chem istry , ▁whose ▁comp ounds ▁are ▁usually ▁est ers . ▁ ▁Thus , ▁for ▁example , ▁the ▁ox al ate ▁mo iety ▁ ▁[ – O – ( C = O ) 2 – O – ] ▁occurs ▁in ▁the ▁est er ▁dim eth yl ▁ox al ate ▁H 3 C – O – ( C = O ) 2 – O – CH 3 . ▁ ▁Dist ributed ▁charges ▁and ▁reson ances ▁ ▁In ▁many ▁ox oc ar bon ▁an ions ▁each ▁of ▁the ▁extra ▁electrons ▁responsible ▁for ▁the ▁negative ▁electric ▁charges ▁behav es ▁as ▁if ▁it ▁were ▁distributed ▁over ▁several ▁atoms . ▁ ▁Some ▁of ▁the ▁electron ▁pairs ▁responsible