Atoms consist of three basic particles: protons, electrons, and neutrons. The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged)
Different atoms have different combinations of subatomic particles. However, there are some general rules regarding the electrical charge of an atom. If the number of protons equals the number of electrons, the atom does not have an electrical charge and is neutral. In other words, the positives and negatives balance out.
Protons and neutrons have similar masses—each proton and neutron has a mass of approximately 1 amu (atomic mass unit). The mass of one electron is even smaller: 1/2000 amu.Remember that the protons and neutrons are located in the atom’s nucleus, which is where most of the atom’s mass is located. Atomic mass is the average mass of all of the protons and neutrons in the atom. Electrons are so small that they not do change the mass of the atom. They do, however, take up a large amount of the volume of the atom.
The following formula can be used to find average atomic mass where
P = number of protons N = number of neutrons:
Atoms are all around us and are the building blocks of all matter. Consider this fact the next time you think chemistry isn’t important.