Experiments
Cathode ray tube experiment that uncovered the existence of the electron
J. J. Thomson
All matter consists of indivisible particles called _____________.
atoms
Rutherford's gold foil experiment revealed that an atom is mostly ____________.
empty space
Robert Millikan
USA
Gold Foil experiment that led to the discovery of the small, positively charged nucleus
Atoms of the same element are _______________ in mass and properties.
identical
J. J. Thomson's model is often referred to as what old-fashioned food?
The "plum pudding" model
J. J. Thomson
Great Britain
No experiments, just philosophy
Democritus
Atoms of different elements ______________ in mass and properties.
differ or vary
Why is Niels Bohr's atomic model often called the "planetary model"?
Bohr proposed that electrons circle the nucleus in fixed orbits like planets around the sun.
Ernest Rutherford
New Zealand
Oil drop experiment to determine the charge of the electron
Robert Millikan
The law of conservation of mass says what about atoms?
Atoms cannot be created, destroyed, or subdivided.
James Chadwick discovered this subatomic particle in 1932.
the neutron
Niels Bohr
Denmark
The examination of emission spectra of hydrogen led to the discovery that electron energy levels are quantized
Niels Bohr
The laws of definite proportions and multiple proportions say what about atoms?
Atoms combine in simple whole‑number ratios to form compounds
The Heisenberg Uncertainty Principle states that matter acts like a particle and a __________.
wave
Werner Heisenberg
Germany