Famous resonance structures
O3, NO2^-, NO3^-, CO3^2–, RCOOH, , C6H6
Elements in hypovalent
Be and B
Elements in hypervalent
Xe, S, Br, I, P, Cl, any element with a d orbit
Double Bonds
o2, co2, c2h4, ch2o
triple bonds
n2, hcn, c2h2
radical/magnet
NO, NO2, O2-
Ionic formula units
AB, AB2, A2B, AB3, A3B, A2B3, A3B2