OK, lets talk about the first statement. An atom is not a tightly compact particle. The largest part of the atom is the electron cloud, which is mostly empty space. The electrons themselves are tiny, even on atom levels; it takes 2000 electrons to equal just one proton or one neutron. So to say an atom is a tightly packed particle is very incorrect, given the massive amount of space provided amongst the electron cloud.
The second statement is inaccurate as well. The electrons are super tiny, as pointed out in the first paragraph, so they afford little protection for the nucleus. That is not why the electrons are there. They are there to provide a counter charge for the poitive charge of the protons, which are located in the nucleus of the atom. For every one positively charge proton, there is one negative electron charge, so the net charge on the atom is zero.