-
460 BCE
Democritus-Leucippus
-Leucippus was the mentor of Democritus and originally came up with the atomic theory, but it was then adopted by Democritus
-All matter consists of invisible particles called atoms that are indestructible
-The particles are solid but invisible, and they are made up from equal elements according to each object
-They differ in size, shape , and composition
-Solids are made of small, pointy atoms
-Liquids are made of big, round atoms
-Oils are made of fine, small atoms that slip past each other -
John Dalton
-Theory developed in 1803
-Born in September 6, 1766
-Died in July 27, 1844.
-Studied meteorology and that made him interested in the study of atoms.
-The theory states that elements are made up from identical atoms for each element.
-This atoms have the same mass and properties.
-Stated that compounds were the special fusion of elements.
-Also said that atoms of different substances have different weights. -
Dmitri Mendeleev
-Developed theory in 1869
-Born february 8, 1834
-Died February 2, 1907
-Creator of the periodic table of elements.
-In this Table the elements are organized by their atomic weight and number.
-With the time more elements were added to the table thanks to constant discoveries. -
Eugen Goldstein
-Developed theory in 1886.
-Born in September 5 of 1850
-Died in 25 of December of 1930,
-He discovered canal rays that are full of ions with a positive charge, basically he discovered protons.
-Used cathode rays that are the ones emitted by electrons when are in a cathodic vacuum to study electrons.
-The atomic model was pictured more accurately thanks to him and that he discovered protons. -
Joseph John Thomson
-Developed 1897 the theory.
-Born December 18, 1856
-Died 30 of August, 1940
-In 1904 delivered six lectures about electricity and matter at Yale University.
-Discovered an atom could be divided which for the past scientist was impossible, also he discovered electrons.
-Won a Nobel prize. -
Ernest Rutherford
-Developed theory in 1907
-He was born on August 30, 1871
-He died on October 19, 1937
-Started his investigations by studying magnetic properties of iron when exposed to High-Frequency Discharges
-Discovered the nucleus of the atom.
-Most of his books were about atoms.
-Proposed the nucleus was made of protons(positive charges) and neutrons, while the electrons that were negative surrounded it.
-Won Nobel Prize of Chemistry. -
Niels Bohr
-Developed theory in 1913
-Born in October 7, 1885
-Died in November 18, 1962
-In Cambridge university he worked in a laboratory leadered by J.J Thomson.
-He based his investigations in Rutherford investigations of the nucleus and helped creating a new and more detailed diagram of the atom.
-This drawing included the number of each particle an atom had.
-The model suggested there were layers that surrounded the nucleus where the electrons orbit.
-Won a Nobel Prize for his atomic model -
Erwin Schrödinger
-Developed his ideas in 1926
-Born August 12, 1887
-Died January 4, 1961
-Based his studies in the atomic model of Niels Bohr
-Stated that the possible positions of electrons could not be determined by the quantum mechanical model of the atom that could predict the odds of the location of an electron
-His model describes a cloud that covers electrons and according to him the places the cloud was denser there is greater probabilities of finding an electron, while in less denser areas there wasn´t -
James Chadwick
-Developed the theory in 1932
-Born 20 of October of 1891.
-Died 24 of July of 1974
-Discovered the neutrons had the same mass of protons.
-Also that the neutrons balanced the protons in the nucleus.
-According to his model electrons that orbited the nucleus were positioned according to the amount of energy they had.
-Discovered that neutrons could be use to create the atomic bomb.
-Won Nobel Prize in physics.
