At least one of these is present in an alkene [read "al-keen"], making it unsaturated, and they are the only bonds present in diatomic oxygen.
Allylic rearrangement occurs when an SN1 substitution shifts the position of this structure, which is forbidden at bridgeheads of ring systems according to Bredt's rule. The Diels-Alder reaction modifies conjugated systems in which these alternate in a ring, often inducing resonance. They are responsible for cis-trans isomerism, and they are formed from overlapping p-orbitals creating a (*) sigma and pi bond. At least one of these is present in an alkene [read "al-keen"], making it unsaturated, and they are the only bonds present in diatomic oxygen. For ten points, identify this covalent bond indicated by two lines on a Lewis dot diagram.
Allylic rearrangement occurs when an SN1 substitution shifts the position of this structure, which is forbidden at bridgeheads of ring systems according to Bredt's rule.
double bond [prompt on partial; prompt on “covalent bond;” do NOT accept any other type] &lt;EC&gt;