Atomic Structure by Jimmy

This topic on the surface is very basic. By definition it is the structure of an atom. As a quick summary of the topic, the current and generally accepted model that is used is a nucleus surrounded by an electron cloud. The nucleus makes up most of the mass of the atom while the electron cloud makes up most of the volume of the atom. The nucleus is made up of two different types of sub-atomic particles. The particles are called neutrons and protons.

The proton and neutron have approximately the same mass, the neutron is slightly more massive, and the same size. However, they have different electrical charges. The neutron, as suggested by the name, has a neutral charge. The proton has a positive charge. The electron is very unlike either of the particles. While the nucleus of the atom is relatively still, the electrons are constantly moving. Electrons are very small, both is mass and size. It has a negative electrical charge. This negative charge has the same numerical value as the positive charge on a proton. This relationship between the charges makes an atom with the same amount of protons and electrons electrically neutral. Most atoms are electrically neutral, but there are some atoms that have an electrical charge, either positive or negative.

The electron cloud is the most recently developed part of the current atomic model. There have been many different models for the atom. The first model that had different particles was the Rutherford model, finalized in 1911. This model was a central nucleus with free floating electrons orbiting the nucleus in a fairly random pattern. While this model was partially accurate, it has many inaccuracies on the points of the electrons. As it was found out by Niels Bohr, electrons will be in specific orbits, rather than a random pattern. Bohr made his model of the atom in 1913. His model was very similar to that of Rutherford; his model was actually called the Bohr-Rutherford model. However the arrangement of the electrons was defined and exact. He came up with three rules for how electrons behaved in an atom. The first rule was that electrons orbit the nucleus. The second was that the electrons could only orbit at a certain distance from the nucleus. Each different layer of electrons was called an electron shell. His third rule was that electrons could jump up or down electron shells, but it required a large amount of energy. His first and third laws still hold today, but his second law was proven to me incorrect in certain circumstances. The current model for electrons is called the atomic orbital model. This model incorporated both ideas from the previous two models. The model stated that electrons could exist anywhere but they were most likely to be in an area. These areas were represented by a density diagram. The areas of the diagram were most darkly colored were the places that were most likely to hold electrons. 

For a long time scientists thought that the electron, neutron, and proton were the smallest particles that existed. However, there are even smaller particles that exist. They are called quarks. These quarks have 6 “flavors”: up, down, strange, charm, top, and bottom. Protons and neutrons are made up of up and down quarks. Since quarks are so small, they cannot be observed by themselves. They can only be observed in other particles, such as protons. As science gets more and more advanced, people keep finding smaller and smaller particles. Will there ever be a definitive “smallest particle”?