Subatomic Particles and the History of the Atom
Modern Atomic Theory: Subatomic Particles
Atoms are composed of three particles: protons, electrons, and neutrons
particle | symbol | charge | location | mass |
---|---|---|---|---|
proton | p^+ | +1 | nucleus | 1 amu |
neutron | n^0 | 0 | nucleus | 1 amu |
electron | e^- | -1 | around nucleus | 1/1836 amu (not significant) |
History of the Atom:
400 B.C. - Democritus
Greek philosopher who theorized that atoms are the building blocks of matter
atomos = āuncuttableā
300 B.C. - Aristotle
Believed everything was made up of 4 elements: earth, fire, air, and water. Also believed that matter had 4 main properties: hot, cold, dry, and wet.
1803 - John Dalton
English chemist, physicist, and meteorologist. Best known for introducing the atomic theory into chemistry.
each element is composed of atoms
atoms of each element are identical, but those of different elements are different
atoms are neither created nor destroyed
1839 - Michael Faraday
His research concluded with the idea that atoms contain particles with electric charge
1897 - JJ Thompson
British physicist credited with discovering the electron, which was the first subatomic particle to be discovered.
Developed a model where negative particles are stuck in a positively charged ion, called the āplum puddingā model.
1911 - Ernest Rutherford
New Zealand physicist who is known as the father of nuclear physics. Discovered that an atom has electrons scattered at a distance from the small positively charged dense nucleus.
Experiment was called the āGold Foilā
1913 - N. Bohr
Danish philosopher, promoter of scientific research, and physicist. Developed the āplanetary modelā of atoms.
Electrons locations are reliant on how much energy they have. Energy levels are located at specific distances from the nucleus.
1926 - Schrodinger
Electrons are found in electron clouds and not paths. They move around the nucleus billions of times in a second.
1932 - James Chadwick
English physicist who discovered that the nucleus of an atom contained a neutral particle with a mass similar to a proton. This particle is called a neutron.
Modern Atomic Theory: Subatomic Particles
Atoms are composed of three particles: protons, electrons, and neutrons
particle | symbol | charge | location | mass |
---|---|---|---|---|
proton | p^+ | +1 | nucleus | 1 amu |
neutron | n^0 | 0 | nucleus | 1 amu |
electron | e^- | -1 | around nucleus | 1/1836 amu (not significant) |
History of the Atom:
400 B.C. - Democritus
Greek philosopher who theorized that atoms are the building blocks of matter
atomos = āuncuttableā
300 B.C. - Aristotle
Believed everything was made up of 4 elements: earth, fire, air, and water. Also believed that matter had 4 main properties: hot, cold, dry, and wet.
1803 - John Dalton
English chemist, physicist, and meteorologist. Best known for introducing the atomic theory into chemistry.
each element is composed of atoms
atoms of each element are identical, but those of different elements are different
atoms are neither created nor destroyed
1839 - Michael Faraday
His research concluded with the idea that atoms contain particles with electric charge
1897 - JJ Thompson
British physicist credited with discovering the electron, which was the first subatomic particle to be discovered.
Developed a model where negative particles are stuck in a positively charged ion, called the āplum puddingā model.
1911 - Ernest Rutherford
New Zealand physicist who is known as the father of nuclear physics. Discovered that an atom has electrons scattered at a distance from the small positively charged dense nucleus.
Experiment was called the āGold Foilā
1913 - N. Bohr
Danish philosopher, promoter of scientific research, and physicist. Developed the āplanetary modelā of atoms.
Electrons locations are reliant on how much energy they have. Energy levels are located at specific distances from the nucleus.
1926 - Schrodinger
Electrons are found in electron clouds and not paths. They move around the nucleus billions of times in a second.
1932 - James Chadwick
English physicist who discovered that the nucleus of an atom contained a neutral particle with a mass similar to a proton. This particle is called a neutron.