An atom is known as the basic unit of a chemical element; however, atoms are no longer considered the smallest particle in existence. From approximately 460 BC to present day 2015, human knowledge about atomic particles has drastically changed. Over the years, research has led to new discoveries involving atoms, subatomic particles, and quarks. Several philosophers including Leucippus, Democritus, Dalton, Thomson, Rutherford, and Gell-Mann have contributed to humanity 's vast knowledge about atomic particles. As technology develops, our perception of atomic particles continues to change.
A number of Greek natural philosophers believed that the universe is composed of physical atoms (Berryman). Approximately 460 BC, the atom was discovered …show more content…
An atom made of thousands of electrons would have a very high, negative electric charge; however, this was not practical, as atoms typically have no charge. In 1906, Thomson suggested that atoms contained far fewer electrons, a number roughly equal to the atomic number. These electrons must have been balanced by a positive charge. Thus, Thomson began studying positively charged ions as he channeled a stream of ionized neon through a magnetic and electric field. He used deflection techniques to measure the charge to mass ratio and discovered that neon was composed of two different kinds of atoms. Nonetheless, the distribution of charge and mass in the atom was unknown. Thomson proposed a 'plum pudding ' model, with positive and negative charge filling a sphere only one ten billionth of a meter ("Cambridge Physics - Discovery of the Nucleus"). This plum pudding model was generally accepted and even Thomson 's student Rutherford, who later disproves the model, believed in it during the time ("Joseph John Thomson | Chemical Heritage Foundation").
J.J. Thomson’s student, Ernest Rutherford, was responsible for several noteworthy discoveries in radioactivity and nuclear physics. Rutherford was born in 1871 on a farm in New Zealand, where he eventually received a scholarship to Cambridge University in 1895. At Cambridge, Rutherford became Thomson’s first graduate …show more content…
Just twenty years ago, physicists were starting to recognize that protons and neutrons are not elementary particles. Instead, they appeared to be composed of puzzling objects called “quarks.” A quark is now defined as an elementary particle that has an electrical charge equal to 1/3 or 2/3 that of an electron or proton (Riordan 608-609). There are six forms of quarks, known as flavors: up, down, strange, charm, top, and bottom. Up and down quarks are normally stable and are the most common in the universe, whereas strange, charm, bottom, and top quarks can only be produced in high-energy collisions.
Today, quarks are recognized as among the elementary particles of which matter is composed. Physicists Murray Gell-Mann and George Zweig individually proposed the quark model in 1964. The main evidence for their existence came from a sequence of inelastic electron-nucleon scattering experiments conducted between 1967 and 1973 at the Stanford Linear Accelerator Center (Riordan
A number of Greek natural philosophers believed that the universe is composed of physical atoms (Berryman). Approximately 460 BC, the atom was discovered …show more content…
An atom made of thousands of electrons would have a very high, negative electric charge; however, this was not practical, as atoms typically have no charge. In 1906, Thomson suggested that atoms contained far fewer electrons, a number roughly equal to the atomic number. These electrons must have been balanced by a positive charge. Thus, Thomson began studying positively charged ions as he channeled a stream of ionized neon through a magnetic and electric field. He used deflection techniques to measure the charge to mass ratio and discovered that neon was composed of two different kinds of atoms. Nonetheless, the distribution of charge and mass in the atom was unknown. Thomson proposed a 'plum pudding ' model, with positive and negative charge filling a sphere only one ten billionth of a meter ("Cambridge Physics - Discovery of the Nucleus"). This plum pudding model was generally accepted and even Thomson 's student Rutherford, who later disproves the model, believed in it during the time ("Joseph John Thomson | Chemical Heritage Foundation").
J.J. Thomson’s student, Ernest Rutherford, was responsible for several noteworthy discoveries in radioactivity and nuclear physics. Rutherford was born in 1871 on a farm in New Zealand, where he eventually received a scholarship to Cambridge University in 1895. At Cambridge, Rutherford became Thomson’s first graduate …show more content…
Just twenty years ago, physicists were starting to recognize that protons and neutrons are not elementary particles. Instead, they appeared to be composed of puzzling objects called “quarks.” A quark is now defined as an elementary particle that has an electrical charge equal to 1/3 or 2/3 that of an electron or proton (Riordan 608-609). There are six forms of quarks, known as flavors: up, down, strange, charm, top, and bottom. Up and down quarks are normally stable and are the most common in the universe, whereas strange, charm, bottom, and top quarks can only be produced in high-energy collisions.
Today, quarks are recognized as among the elementary particles of which matter is composed. Physicists Murray Gell-Mann and George Zweig individually proposed the quark model in 1964. The main evidence for their existence came from a sequence of inelastic electron-nucleon scattering experiments conducted between 1967 and 1973 at the Stanford Linear Accelerator Center (Riordan