Protons, neutrons, and electrons

Elements make up compounds, and are considered the basic building blocks of matter. You cannot break down elements into smaller parts, but you can classify the different parts within the element. Within the element are protons, neutrons, and electrons. The neutron, a chargeless particle, can be found in the nucleus along with the proton, which is a particle only slightly smaller than the neutron but positively charged. Electrons are negatively charged and are found circling the nucleus (much like the sun and the planets in our solar system).
Within the atom, one can find a nucleus. The nucleus, which does not move around like electrons, contains both neutrons and protons. Both neutrons and protons have mass, and these two contribute almost 100% of the atomic mass of an element. Electrons, on the other hand, have almost no mass. Most calculations assume a mass of zero for electrons. Electrons, being so small, can move around very quickly around the nucleus. Protons and neutrons can also be broken down into quarks, but you won't learn about those petit particles in this chemistry year.
A common demonstration to show how little space the electrons and nucleus take up in the atom is with the football field analogy. If a football stadium was considered to be an atom, a feather on the 50 yard line would be the nucleus. That is how much empty space there is within an atom!