.
.
. 500 B.C.
.
. 442 B.C. Democritus co-originated the idea with his teacher, Leucippus, that matter is composed of indivisible elements.
.
.
. 1800
.
.
. 1803 John Dalton proposed the idea that matter is composed of atoms of different weights and is combined in ratios by weight. Also proposed that atoms are spherical and are in motion.
.
.
. 1850
.
.
. 1898 Pierre and Marie Curie propose the idea that radioactive particles cause atoms to break apart, then releasing radiation that takes the form of energy and subatomic particles.
.
. 1898 JJ Thomson discovers the electron by using properties of cathode rays.
. 1900
. 1905 Albert Einstein, creates special and general theories of relativity, and hypothesizes about the particle nature of light. This was the basis of nuclear energy.
.
. 1908 Robert Millikan measured the charge of one electron. Known as the elementary charge, one of the fundamental physical constants.
.
. 1909- Ernest Rutherford, also known as the father of nuclear physics, developed the theory for the structure of the atom. Used a gold foil experiment, observing the scattering of alpha particles, and demonstrated for the existence of the atomic nucleus.
.
. 1913 Neils Bohr developed the Bohr atomic model, with electrons travelling in orbits around the nucleus, and chemical properties being determined by how many electrons are in the outer orbits. He also integrated the Planck quantum theory, which says that when electrons change orbits they put off a quantum of discrete energy.
.
.
. 1931 James Chadwick discovers the neutron component of the atomic nucleus, which explains the nuclear fission of uranium 235. This also made it possible to make elements heavier than uranium in the lab.
.
.
. 1964 Mann theorizes the quark model, which describes elementary particles that have no substructure (and therefore can't be split).
Resource for timeline: http://www.softschools.com/timelines/atomic_theory_timeline/95/
.
. 500 B.C.
.
. 442 B.C. Democritus co-originated the idea with his teacher, Leucippus, that matter is composed of indivisible elements.
.
.
. 1800
.
.
. 1803 John Dalton proposed the idea that matter is composed of atoms of different weights and is combined in ratios by weight. Also proposed that atoms are spherical and are in motion.
.
.
. 1850
.
.
. 1898 Pierre and Marie Curie propose the idea that radioactive particles cause atoms to break apart, then releasing radiation that takes the form of energy and subatomic particles.
.
. 1898 JJ Thomson discovers the electron by using properties of cathode rays.
. 1900
. 1905 Albert Einstein, creates special and general theories of relativity, and hypothesizes about the particle nature of light. This was the basis of nuclear energy.
.
. 1908 Robert Millikan measured the charge of one electron. Known as the elementary charge, one of the fundamental physical constants.
.
. 1909- Ernest Rutherford, also known as the father of nuclear physics, developed the theory for the structure of the atom. Used a gold foil experiment, observing the scattering of alpha particles, and demonstrated for the existence of the atomic nucleus.
.
. 1913 Neils Bohr developed the Bohr atomic model, with electrons travelling in orbits around the nucleus, and chemical properties being determined by how many electrons are in the outer orbits. He also integrated the Planck quantum theory, which says that when electrons change orbits they put off a quantum of discrete energy.
.
.
. 1931 James Chadwick discovers the neutron component of the atomic nucleus, which explains the nuclear fission of uranium 235. This also made it possible to make elements heavier than uranium in the lab.
.
.
. 1964 Mann theorizes the quark model, which describes elementary particles that have no substructure (and therefore can't be split).
Resource for timeline: http://www.softschools.com/timelines/atomic_theory_timeline/95/
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When and where did Democritus live?
Democritus lived from 460 BCE to 370 BCE in Greece.
Democritus lived from 460 BCE to 370 BCE in Greece.
What information did they contribute to the understanding of the atom?
Democritus was the first to propose the idea that matter wasn't infinitely divisible. He believed matter was made up of particles called atomos, which he belived couldn't be created, destroyed, or further divided.
Democritus was the first to propose the idea that matter wasn't infinitely divisible. He believed matter was made up of particles called atomos, which he belived couldn't be created, destroyed, or further divided.
What experiments did he do to find his information?
To prove that atoms couldn't be broken down any further, Democritus would take a seashell and continuously break it in half until he was left with only a fine powder. Then he would try to break apart the powder, and he could not. He thought this experiment backed up this theory.
To prove that atoms couldn't be broken down any further, Democritus would take a seashell and continuously break it in half until he was left with only a fine powder. Then he would try to break apart the powder, and he could not. He thought this experiment backed up this theory.
Interesting facts about Democritus:
- Democritus often looked happy while he worked, so people would call him "The Laughing Philosopher"
- Democritus also studied astronomy, zoology, physics, botany, and medicine. He didn't just limit his studies to atoms.
- Democritus also made contributions to the studies of math and sciences such as biology and anthropology.
Resources for questions:
- http://www.egs.edu/library/democritus/biography/
- http://thelittleguy22.tripod.com/id1.html
- http://www.softschools.com/facts/scientists/democritus_facts/721/
- http://democrituspd8.weebly.com/interesting-facts.html