# How are SN1 reactions written?

$\text{S"_"N} 1$ reactions are stepwise, unimolecular substitution reactions. They usually undergo 2-5 steps: here's a mechanism I made up (more representative of solvolysis, a process that takes on this substitution mechanism),
Since the rate-determining step is the loss of a leaving group, we want excellent leaving groups. Moreover, since $\text{S"_"N} 2$ mechanisms want strong nucleophiles for the same reason, an average strength nucleophile works in unimolecular substitution (hence why we can use a neutral nucleophile like methanol).