SN2

[LannaP]

What is the best way of identifying a reaction as SN2 or electrophilic addition when observing the mechanism?

[Rachel Risoleo 3G]

An SN2 reaction is a single-step mechanism substitution reaction. An electrophilic addition reaction's primary identifying characteristic is the addition of an electrophile to a larger molecule.

[vannahyazon 1L]

Like noted above, SN2 is a single step mechanism.

So if you create a one step mechanism, and the starting molecule does not look like the end molecule after that first step, then it will be electrophilic addition, because there are more steps to match the starting molecule and the end molecule.

As noted again, this is because you are typically dealing with a larger molecule.