is there a lower limit on the size of a nuclear bomb?

Question

And if so, what factors determine it?

I know that the scale of the explosion is an insane amount larger than the teeny molecules causing it, but I’m wondering if there could ever be nuclear explosions small enough to take out a single house or block, rather than a whole city from high above.

In: Physics

Answer 1

There are two

The complicated one: critical mass. TL;DR is you need a certain mass (the exact amount depending on what radioactive element you use) before the chain reaction starts, otherwise you don’t gain more energy than you lose, so no boom. (Extremely oversimplified, obviously)

The easy one: practicality. Why use a nuke if a grenade does the job just fine and won’t make it so entering the blast zone 500 years after detonation will still give you cancer?