There are three basic parts to an atom. The parts are the electrons, protons, and the neutrons. In the periodic table there are over 100 elements, and all of them have different amount of electrons, protons, and neutrons. The protons and the neutrons are always in the center of the atom, or also known as the nucleus of the atom. The electrons are always surrounding the nucleus which are called orbitals. The protons are positively charged particles and weigh about 1/1837 Atomic Mass Unit, and the neutrons are neutrally charged particles and weigh about 1 Atomic Mass Unit. The electrons that are surrounding the nucleus are negatively charged particles and weigh about 1 Atomic Mass Unit. The electrons surrounding the nucleus are called the electronic cloud. Each orbital carries certain amounts of electrons. The Octet rule tells you how many electrons are in each layer of orbitals. In the first layer, “K” there are 2 negatively charged electrons, in the second, “L” there are 8 negatively charged electrons, same goes for the the next one “M”. Now the fourth layer “N” can consist of 8 or 18 negatively charged electrons, and the fifth layer “O” can consist of ether 8,18,32 negatively charged electrons. In the periodic table the elements have two numbers, one above and to the left and the other one below and to the left. These numbers represent the atomic number and the atomic mass. The atomic number represents how many protons and electrons there is in that atom. To find the number for neutrons you have to take the atomic number and subtract it from the atomic mass, and you will get the answer.