Leucippus and Democritus

5th century BCE (around 430 BCE) - Proposed that all matter is made of indivisible particles called atoms; atoms are eternal, solid, and move through empty void; different atomic shapes and sizes create different properties of matter

4th century BCE (around 380 BCE) - Presented atomist physical theories in his philosophy; influenced discussion of matter and elements

4th century BCE (384-322 BCE) - Rejected atomic theory; proposed all matter is made of four elements (earth, water, air, fire) which could transform into each other; this theory delayed acceptance of atomic theory for centuries

1803 - Developed modern atomic theory; proposed atoms are indivisible particles, all atoms of same element are identical, atoms combine in fixed ratios to form compounds; established Law of Multiple Proportions

1897-1904 - Discovered the electron through cathode ray experiments in 1897; proposed plum pudding model in 1904 where negatively charged electrons are embedded in positively charged sphere

1909 - Conducted oil drop experiment to measure the charge of an electron; proved electric charge is quantized and exists in discrete units

1911 - Conducted gold foil experiment; discovered the atomic nucleus by observing alpha particle deflection; proposed nuclear model where positive charge and most mass are concentrated in tiny central nucleus

1900 - Proposed quantum theory to explain blackbody radiation; introduced the concept that energy is emitted in discrete packets (quanta) rather than continuously; laid foundation for quantum mechanics

1905 - Applied Planck's quantum hypothesis to explain the photoelectric effect; showed light consists of particle-like photons; demonstrated quantum theory applies beyond blackbody radiation

1913 - Proposed model where electrons orbit nucleus in specific energy levels or shells; electrons can only exist in certain quantized orbits; explained atomic spectra of hydrogen through electron transitions between orbits

1925-1927 - Developed matrix mechanics formulation of quantum mechanics in 1925; formulated uncertainty principle in 1927 stating position and momentum cannot both be precisely determined simultaneously

Help

Options

focusNode

Didn't know it?
click below

Knew it?
click below

Don't Know

Remaining cards (0)

Know

retry

shuffle

restart

0:00

Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

Normal Size Small Size show me how

Stack #4545042

Question	Answer
Leucippus and Democritus	5th century BCE (around 430 BCE) - Proposed that all matter is made of indivisible particles called atoms; atoms are eternal, solid, and move through empty void; different atomic shapes and sizes create different properties of matter
Plato	4th century BCE (around 380 BCE) - Presented atomist physical theories in his philosophy; influenced discussion of matter and elements
Aristotle	4th century BCE (384-322 BCE) - Rejected atomic theory; proposed all matter is made of four elements (earth, water, air, fire) which could transform into each other; this theory delayed acceptance of atomic theory for centuries
John Dalton	1803 - Developed modern atomic theory; proposed atoms are indivisible particles, all atoms of same element are identical, atoms combine in fixed ratios to form compounds; established Law of Multiple Proportions
J.J. Thomson	1897-1904 - Discovered the electron through cathode ray experiments in 1897; proposed plum pudding model in 1904 where negatively charged electrons are embedded in positively charged sphere
Robert Millikan	1909 - Conducted oil drop experiment to measure the charge of an electron; proved electric charge is quantized and exists in discrete units
Ernest Rutherford	1911 - Conducted gold foil experiment; discovered the atomic nucleus by observing alpha particle deflection; proposed nuclear model where positive charge and most mass are concentrated in tiny central nucleus
Max Planck	1900 - Proposed quantum theory to explain blackbody radiation; introduced the concept that energy is emitted in discrete packets (quanta) rather than continuously; laid foundation for quantum mechanics
Albert Einstein	1905 - Applied Planck's quantum hypothesis to explain the photoelectric effect; showed light consists of particle-like photons; demonstrated quantum theory applies beyond blackbody radiation
Niels Bohr	1913 - Proposed model where electrons orbit nucleus in specific energy levels or shells; electrons can only exist in certain quantized orbits; explained atomic spectra of hydrogen through electron transitions between orbits
Werner Heisenberg	1925-1927 - Developed matrix mechanics formulation of quantum mechanics in 1925; formulated uncertainty principle in 1927 stating position and momentum cannot both be precisely determined simultaneously

Created by: Karz

"Know" box contains:
Time elapsed:
Retries: