Atomic model timeline use

Aristotle

335

Aristotle was born in 384 B.C. in Stagira, Greece. his atomic theory was all matter is made of the four elements: fire, water, earth and air. Aristotle also believed that there were four qualities to these elements: dryness, hotness, coldness and moistness. These beliefs based Aristotle’s theory that fire would have the characteristics of dryness and hotness and water is wet and cold etc. Aristotle came up with his atomic model around 335 BC.

Democritus

465

Ancient reports say that Democritus was born around 460 B.C.E in Abdera. Democritus’s theory on atoms is everything is composed of atoms. Atoms are physically but are not geometrically invisible. Atoms are indestructible. Atoms will always be in motion and there are an infinite number of atoms which differ in shape and size. Democritus came up with atomic model around the year 465 BC.

Antoine Lavoisier

Apr 1, 1789

Antoine Lavoisier proved the law of conservation of mass in 1789. The law states that mass cant be created nor destroyed and the mass of the reactants must be equal the mass of the products. He also proved that when oxygen and hydrogen are combined you get water. Antoine Lavoisier was born in 1743 and died in 1794.

Dmitri Mendeleev

Apr 2, 1865

Dmitri Mendeleev was born in 1834 and he lived till 1907. Mendeleev is best known for his work on the periodic table with he did by arranging the 63 known elements based in the atomic mass of that certain atom. Dmitri Mendeleev did these findings between the years of 1860 and 1870.

J.J. Thomson

Apr 2, 1904

JJ Thomson came up with the plum pudding model in 1904. J.J Thomson’s atomic theory was that the atomic model was something like a plum pudding. He thought that the basic setup of an atom is spherical containing negative electrons confined in a massive positive charge; the positive and negative charges cancel each other out. J.J. Thomson lived from 1856 to 1940.

John Dalton

Apr 1, 1911

John Dalton was born in 1766 and died in 1844. John Dalton’s theory was matter is composed of microscopic particles called atoms. All atoms of an element are identical, but differ from any atom from a different element. During chemical reactions atoms are neither created nor destroyed but they are rearranged. Atoms always combine in whole number multiples of each other e.g. 1:1, 1:2, 2:3, 1:3. John Dalton developed the atomic theory of matter around 1803

Ernest Rutherford

Apr 2, 1911

Ernest Rutherford was born on the 30th of August 1871, in Nelson, New Zealand. The Rutherford atomic model is described as a tiny positively charged core called the nucleus. Negative constituents called electrons circulate around the nucleus. The Rutherford atomic model has been called the nuclear atom or the planetary model of the atom. 1911 was when Ernest Rutherford discovered the nucleus and electrons by doing the gold foil experiment.

Fredrick Soddy

Apr 2, 1912

English chemist Frederick Soddy was born on the 2nd of September in Eastbourne, Sussex, England. Frederick Soddy proposed in 1912 that the same elements exist in different forms, a nucleus having the same number of protons but they have a different number of neutrons. His theory of isotopes explains that different elements can be indistinguishable but have different weights and characteristics.

H.G.J Moseley

Apr 2, 1913

Henry Moseley was born in 1887 and died in 1915 at Gallipoli in world war 1. H.G.J Moseley determined the charges of most atoms. He said the atomic number of an element is the same as the number of protons in the nucleus instead of the atomic mass. Henry Moseley used the application of X-ray spectra to study the structure of an atom.

Niels Bohr

Apr 2, 1915

Niels Bohr was born on the 7th of October, 1885, in Copenhagen, Denmark. Niels Bohr proposed his atomic model in 1915. Bohr’s model is a modification of Ernest’s Rutherford’s atomic model. Bohr’s model is a planetary model, which the electrons orbits a positively charged nucleus. The Bohr model is very similar to the planets orbiting the sun.

Ernest Rutherford

Apr 2, 1920

James Chadwick was born in 1891 and he passed away in 1974. As of 1930 only the proton and the electron had been discovered. Protons were positive and the electrons had a negative charge. Moseley showed that the charge increases in steps of a one proton as you go up the periodic table. To account for this it was apparent that the nucleus of each atom contains a number of protons to equal its atomic number. In order to remain electrically neutral it also was thought to contain an equivalent numbe

Werner Heisenberg

Apr 2, 1927

Werner was born of December 5th, 1901 in Wurzburg, Germany. He died on the 1st of February 1976 of cancer. Werner calculated the behaviour of electrons and subatomic particles that make up an atom. Werner focused on mathematics instead of scientific terms to understand the pattern of atoms electrons. Werner’s discovery helped to clarify the view of an atom because scientists can compare the number of atoms there are by their movements of electrons, and how many electrons are inside of an atom.

James Chadwick

Apr 2, 1932

James Chadwick was born in 1891 and he passed away in 1974. Protons were positive and the electrons had a negative charge. Moseley showed that the charge increases in steps of a one proton as you go up the periodic table. To account for this it was apparent that the nucleus of each atom contains a number of protons to equal its atomic number. In order to remain electrically neutral it also was thought to contain an equivalent number of electrons. The difficulty remaining was the job of accountin

Murray Gell-Mann and George Zweig

Apr 2, 1964

Murray Gell-Mann and George Zweig put forward the idea of quarks in 1964. They suggested that mesons and baryons are combined of three quarks or antiquarks, with the names up, down and strange. Their theory was found not to be entirely accurate.