States that matter is composed of extremely small particles called atoms; all atoms of the same element are identical; atoms cannot be created, destroyed, or divided into smaller particles.
Proposed that matter was not infinitely divisible, but instead made of tiny individual particles called atomos.
Used the Cathode Ray tube to determine the charge-to-mass ratio of the electron; mass much less than that of the atom - meant atom was made of smaller particles; plum pudding model
proved the existence of negatively charged particles; constructed a glass tube with wires inserted in both ends, and pumped out as much of the air as they could, an electric charge passed across the tube from the wires would create a fluorescent glow
Gold foil experiment: (atom is mostly empty space, atoms contains a dense, positively charged nucleus); discovered protons.
Gold Foil Experiment
This was Ernst Rutherford's experiment that led to the discovery of the nucleus as the small, dense, positively charged center of the atom and the development of the nuclear theory of the atom.
model of the atom in which electrons move rapidly around the nucleus in paths called orbits
formulated a mathematical formula that describes probable area called orbitals where electrons are most likely located = quantum mechanical model in 1926
If all particles are "waving," the it is impossile to know the object's velocity and position at the same time. To know one, we have to "stop" the other
discovered the neutron
Smallest particle of an element that retains all the properties of the element, electronically neutral, spherically shaped, and composed of electons, protons, and neutrons
Negatively charged, fast moving particle with an extremely small mass thta is found in all forms of matter and moves through the empty space surrounding an atom's nucleus
The extremely small, positively charged, dense center of an atom that contains positively charged protons and neutral neutrons
A subatomic particle in an atom's nucleus that has a positive charge of 1+
A neutral, subatomic particle in an atom's nucleus that has a mass nearly equal to that of a proton
The number of protons in an atom
Atoms of the same element with different numbers of neutrons
The number of an element's name, representing the sum of its protons and neutrons
Atomic Mass Unit (amu)
One-twelfth the mass of a carbon-12 atom
The weighted average mass of the isotopes of that element
Calculating weighted average atomic mass of an element