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Discovered electron in 1897; known for plum
pudding model. Cathode ray experiment.
Discovered isotopes of elements.
Another founder of quantum mechanics;
famous for cat analogy
Wave-particle duality theory of light meaning
electrons have properties of both waves and
particles
Discovered protons in 1900; anode ray
experiment; said that since atoms contain
negatively charged particles, they must also
contain positively charged particles in order to
remain electrically neutral
Planetary model of atom; Electrons move
around the nucleus in fixed orbits, paths, or
energy levels; spectrum lines produced when
electrons move
Greek philosopher; first to identify possibility
of an atom; said matter made of smallest
particles called atomos which means
indivisible.
Law of Definite Proportions = always have the
same proportions of elements by mass (H2O is
always 2 hydrogen and 1 oxygen)
Discovered neutrons in 1932 which led to
discovery of fission and the atomic bomb;
helped with the development of the nuclear
model
Founder of quantum mechanics; uncertainty
principle; impossible to determine the position
and the momentum of a particle at the same
time; “cloud” model aka quantum mechanical
model
Discovered atoms have a small positive
nucleus and remainder is empty space; gold
foil experiment; predicted existence of
neutrons
Observed isotopes
Father of modern atomic theory that he
proposed in 1808; developed concept of the
mole; proposed system of symbols
Dismissed Democritus’ atom idea as worthless; Founder of quantum theory; atoms can emit
believed in reasoning instead of scientific
‘quanta’; Einstein used his work to study
experiments; four ‘elements’ of earth, fire, air, photons; Planck’s constant
water
Law of Conservation of Mass = matter not
created or destroyed, just changed in a
reaction; named oxygen
Oil drop experiment; measured charge of
electron; worked with Thomson