The Components of the Atom

While the cell is the basic building block of living things, the atom is the basic building block of matter.  Everything from the largest galaxy to the amoeba consists of a collection of atoms.  While our understanding of the atom may be only centuries old, the study of this tiny chemical powerhouses has gone on for centuries.  And, any discussion about the atom would be incomplete without an explanation of its components.


While many may confuse the atom with a Silver Age comic book character, the atom is genuinely more than a man in tights.  The term atom derives from the Greek word atamos, which means something that cannot be further divided.  Atoms are the smallest component of an element that also carries its chemical properties. 

Atoms can be split which releases incredible amount of energy.  Atoms can bond with others and form familiar substances such as salt, water, and air. Atoms can release parts and create the daily nuisance of static electricity.  Atoms can decompose and aid doctors in diagnosing and treating illnesses.

The atom is best described as a mini solar system.  Consisting of  protons, neutrons, and electrons, the electrically neutral atom has a core which orbiting parts. These component particles carry electrical charges which are the root at all chemical reactions. 


The proton is the positively charged part of the atom. It exists in the core, or nucleus, of the atom.  Discovered by Rutherford in 1919, the  proton is a composite particle made up of two up quarks and one down quark.  This subatomic particle is stable by itself.

The hydrogen atom, which has one proton, had originally confused scientists and many believed all elements contained hydrogen. Then, scientists realized that there must be a hydrogen-like particle. As early as 1815, researchers were trying to decipher the make-up of the atom. By 1911, Ernest Rutherford was on the trail of the answer and discovered the atomic nucleus.  And, in 1919, Rutherford and his team discovered the elusive proton.   


While the proton was discovered in the early 1900s, it was not the first subatomic particle discovered.  In 1897,  Sir. Joseph John Thomson studying cathode rays found the negatively charged particle found in atoms.

Electrons do not rest in the nucleus, but instead orbit around the atomic nucleus in zones called shells.  Electrons are considered elementary particles, because unlike protons, they do not consist of quarks or smaller particles.  An electron’s mass is about 1/1836 of a proton.  Chemical reactions, electromagnetism, gravity and even static electricity are linked to the bonding power of the electron. 


The neutron is the subatomic particle that shares the atomic nucleus with the proton. Made up of two down and one up quarks, the neutron has diametrical opposite composition than the proton.  Neutrons have no net charge and are only stable if bonded in the atomic nucleus.  While neutrons are not found in helium atoms, they exist in the core of all other elements.

After the discovery of the electron and the proton, Rutherford theorized that the atomic nucleus contains particles other than the proton.  More than ten years after Rutherford discovered the proton, the neutron confirmed by British physicist James Chadwick in 1932.  Chadwick actually discovered the neutron through the combination of methods and understanding other laws of physics, namely the laws of conservation of momentum and energy. 

Neutrons are linked to processes such as radiation and gamma ray emissions.  They are important in understanding nuclear reactions.


For every element, there is an atom.  At last count, there were over 112 known elements. The elements are arranged by their chemical behaviors and properties on what many refer to as the Periodic Table of the Elements.

Once organized, the pattern for the elements reveal that the relationship of electrons, protons, and neutrons form everything from alkali metals to noble gases. Also, the chart reveals that the stability and chemical bonds of the elements depends on the stability of the nucleus and the availability of free electrons. 


While it has taken hundreds of years to learn the basic components of the atom, scientists have put the information to great use in the field of chemistry, physics and medicine.  Understanding the nature of the atom helps science explore the mysteries of the universe.

For more information on the atom and its components, check out the following websites: