Studied by 3 peopleWhen did Democritus live?
around 460 BC
What was Democritus’ background?
lived in Abdera, Greece but not much known about his early life
what inspired Democritus’ model?
Parmenides’ challenge saying that all matter is in a state of not being or being
what did Democritus’ model show?
all atoms are tiny indivisible particles that move using hooks and barbs, are infinite in number and variation of size and shape, and cause properties of substances
was Democritus’ model accepted?
no
when did John Dalton live?
1766-1844
what was Dalton’s background?
English chemist and physicist who previously studied meteorology in manchester
what inspired Dalton’s model?
he set out to scientifically prove Democritus’ model
what are Dalton’s five tenets?
all matter is composed of atoms
atoms of elements are the same
atoms are indivisible and neither created or destroyed
atoms of separate elements can combine in simple whole-number ratios to form compounds
in chemical reactions, atoms are combined, separated, or rearranged
was Dalton’s model accepted?
it was a start but did not talk much about the atoms themselves
when did Lord Kelvin live?
1824-1907
what was Lord Kelvin’s background?
lived in Belfast, Ireland, originally named William Thomson, studied as a mathematician, physicist, and engineer
what inspired Lord Kelvin’s model?
the movement of smoke rings like a vortex and sailor knots
what did Lord Kelvin’s model show?
atoms twist and turn like knots
was Lord Kelvin’s model accepted?
it was forgotten due to his more famous inventions like the Kelvin absolute temperature scale and the mariner compass and also because he had no scientific proof
when did J.J. Thomson live?
1856-1940
what was Thomson’s background?
originally wanted to be an engineer but had financial issues and became a physicist at Owen’s college who liked to tinker around with stuff
what inspired Thomson’s model?
his cathode ray experiment finding corpuscles or electrons and plum pudding
what did Thomson’s model show?
atoms contained negative particles floating within a soup of diffuse positive charge
was Thomson’s model accepted?
his model was soon found to have many problems including no nucleus
when did Robert Millikan live?
1868-1953
what was Robert Millikan’s background?
lived in Morrison, Illinois in a rural community, studied mathematics at Oberlin College and worked with optics, molecular physics and electricity
what inspired Millikan’s model?
his water and oil drop experiments
what does Millikan’s model show?
concrete proof of electron’s negative charge and the amount of charge in an electron
was Millikan’s model accepted?
yes because he had concrete proof
when did Ernest Rutherford live?
1871-1937
what was Rutherford’s background?
lived in rural spring grove, new zealand as the one of 12 kids, was interested in science at a young age, studied at canterbury college and worked in cavendish’s lab
what inspired rutherford’s model?
his gold foil experiment
what did rutherford’s model show?
determined the presence of the nucleus
was rutherford’s model accepted?
yes except no reason for why electrons orbit the nucleus
when did niels bohr live?
1885-1962
what was bohr’s background?
lived in copenhagen as 2 of 3 kids in an upper middle class family, studied physics at the university of copenhagen and polytechnic institute
what inspired bohr’s model?
wanted to try to solve the problems with rutherford’s model using quantum model
what did bohr’s model say?
electrons are found in energy levels or shells and electrons only move by absorbing or emitting energy
was bohr’s model accepted?
considered radical for a while but now widely used by teachers even though it only works for the lighter elements and violates the Heisenberg uncertainty principle
when did james chadwick live?
1891-1974
what was chadwick’s background?
attended manchester university and studied under rutherford and went to study in berlin but was imprisoned in an internment camp for 4 years during WW1 and after release worked in cavendish’s lab
what inspired chadwick’s model?
interested in the bombardment of particles and determined the mass of each particle was over the mass of a proton
what did chadwick’s model say?
he found and proved the existence of a neutron
was chadwick’s model accepted?
yes
when did erwin schrodinger live?
1887-1961
what was schrodinger’s background?
lived in vienna, austria and was widely educated, enlisted in WW1 but returned to research after
what inspired schrodinger’s model?
applied quantum theory
what did schrodinger’s model say?
theorized that electrons have wavelike behavior and are found in orbitals in the electron cloud
was schrodinger’s model accepted?
it is the most recent and accurate model
why did plato reject democritus’ theory?
democritus had based his model on philosophy and did not have scientific proofw
why did aristotle reject democritus’ theory?
he believed everything was made of earth, water, air, and fire
why did the roman catholic church reject democritus’ theory?
it is never said in the bible that God created atoms
what is a corpuscle?
thomson originally called electrons corpuscles
what is an atom?
An atom is made up of a nucleus of positively charged protons and electrically neutral neutrons, with negatively charged electrons orbiting around it
what is a cathode ray tube?
a vacuum tube that has two charged plates on either end that when a voltage flows through turns pink
what is the plum pudding model?
this was thomson’s model that said an atom was a cloud of positive matter with embedded negative particles making the model look like plum pudding
what was the oil drop experiment?
has atomized oil particles pass through a charged metal plate and then getting radiated and being suspended by voltage
what was the gold foil experiment?
when alpha particles are fired at a gold sheet within a detecting screen most particles passed through but a few reflected back
what order did the 9 atomic models occur?
democritus
dalton
lord kelvin
thomson
millikan
rutherford
bohr
chadwick
schrodinger
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