How big is Chlorine Nucleus?

Electrons are so small that their size can't accurately be measured. The size of an electron varies greatly depending on how it's measured, whether it's based on the quantum model or, in this case, the classical model.

The helium nucleus is thousands of times smaller than the atom, like a marble in a football field. The only reason matter feels solid is because atoms repel. If atoms didn't repel, everything would fall through each other!

Neutrons are found within an atom's nucleus. They are thousands of times smaller than the atom itself. They have two down quarks and one up quark. Therefore, the neutron's charge is -1/3-1/3+2/3 = 0.

Uranium is the heaviest natural element. It also has the largest nucleus of all the natural elements. Uranium-238, the most common isotope of uranium, has a half-life of 4.5 billion years, approximately the time the Earth has existed.

Gamma rays have a very high frequency. They can come from radioactive decay. Oh, and by the way, it's not actually light blue as it appears to the left.

Electron microscopes allow us to see very small things (like atoms) that would otherwise be invisible because they are smaller than the wavelength of visible light.