How to turn object into scrap when hit hard?

I alredy fixed the falling skyscraper problem it falls very neat but i want to make it so that when the building hits the ground it appears alot of smoke,and turns itself into scrap.like destroying the original object and spawning a scrap gameobject, can anyone give me the script? it should have the variables:force it needs to turn into scrap(force to activate),particles to use for explosion(what particles or smoke will appear when the building hits),and gameobject to spawn when the building gets destroyed.Its fairly simple i just dont know scripting.Thks for reading