What happens to an atom when the atomic mass number changes and the atomic number stays the same ?

What happens to isotopes that are unstable?

In a heat engine of 1000 j of heat enters the system and the piston does 500 j of work what is the final internal energy of the system if the inital energy was 2000 j we have to do all of these down here 1)write the equation 2)list out your know variables 3)plug the numbers into the equations 4)solve 5)write your solution statemtn that includes inital energuy and final energuy added

Which states of matter have particles that move independently of one another with very little attraction?