Now, it's generally taught ( and even visualised) that atoms are like balls which bump when collided with other atoms. And it's also said that electrons collide with atoms. I am reading the drude model of electrical conductivity, there one of assumptions was made that electrons collide with ions. I actually have a problem with that, which is that when I say an atom It doesn't have any layer covering nucleus and electrons. It simply means nucleus together with electrons right? Now the same applies to ion as well. So my doubt is if we don't have any layer covering atoms why electrons are said to bounce off with atoms or molecules or ions? In simpler terms my doubt is what does electrons bouncing of ions really mean? Does it mean like atoms are balls through which electrons are bounced off?

Now, it's generally taught (and even visualised) that atoms are like balls which bump when collided with other atoms. And it's also said that electrons collide with atoms. I am reading the Drude model of electrical conductivity, there one of assumptions was made that electrons collide with ions. I actually have a problem with that, which is that when I say an atom it doesn't have any layer covering nucleus and electrons. It simply means nucleus together with electrons right? Now the same applies to ion as well. So my doubt is if we don't have any layer covering atoms why electrons are said to bounce off with atoms or molecules or ions? In simpler terms my doubt is what does electrons bouncing of ions really mean? Does it mean like atoms are balls through which electrons are bounced off?