Timeline project by Alyzah Nation Ledezma

Aristotle & Democritus

27anation — 2025-09-12 14:58:50 UTC

400 B.C. Aristotle believed that all matter was made of 4 elements: Earth, Air, Fire, and Water. Everyone believed Aristotle because you could see the elements Aristotle believed all matter was created from.

Democritus on the other hand believed that everything is composed of small atoms. atoms could come in different shapes and sizes, but no one believed him because they couldn't see it.

John Dalton

27anation — 2025-09-12 15:07:07 UTC

John Dalton continued Democritus's theory in 1809. His theories were based on observations and experiments.

Matter is made of small particles or atoms
Atoms cannot be created nor destroyed
All atoms of an element are identical and have the same mass
Atoms of different elements have different masses
Compounds are formed by combining different elements
John believed atoms were small, solid particles

War of the Fifth Coalition-10 Apr 1809

27anation — 2025-09-12 15:16:33 UTC

Archduke Charles of Austria invades Bavaria with 200,000 men, sparking the War of the Fifth Coalition. The war of the fifth coalition was a major conflict of the Napoleonic wars, it was fought temporarily in central Europe between the first French empire and its client states against the Austrian empire, supported by the United kingdom. the six-month conflict was the final victorious war in the career of emperor Napoleon I.

J.J. Thompson

27anation — 2025-09-12 15:31:05 UTC

In 1897 an English physicist named J.J. Thompson did experiments to determine the parts that make up the atom. He used a cathode ray tube: a vacuum tube where all the air has been pumped out and a limited amount of other gases pumped in. The experiment was passing an electric current, it makes a beam appear to move from the negative to the positive, by adding and electric field to the outside of the tube, he discovered that the moving pieces were negative. The negatively charged particles were called corpuscles by Thompson but the name was later changed to electrons. Thompson developed a model based on his findings and it was called the plum pudding model. looks like a chocolate chip cookie.

The Korean Empire 1897-1910

27anation — 2025-09-12 15:45:10 UTC

Officially the empire of Korea or imperial Korea, was a Korean monarchical state proclaimed in October 1897 by King Gojong of the Joseon dynasty. The empire lasted until the Japanese annexation of Korea in august 1910. During this period, Emperor Gojong oversaw the Gwangmu Reform, a partial modernization and westernization of Korea's military, economy, land system, education system, and various industries. In 1905, the Korean empire became a protectorate of the empire of Japan. after the Japanese annexation in 1910, the Korean empire ceased to exist.

Ernest Rutherford

27anation — 2025-09-16 17:15:15 UTC

In 1910, an English physicist named Ernest Rutherford continued Thompson's work. He believed the plum pudding model was correct, but wanted to discover the size of atoms. To do that Rutherford used thin gold foil sheets and Radioactive material. The radioactive material released alpha particles, which would glow when in contact with the fluorescent screen. The explanation from Rutherford is atoms are mostly empty space, there is a small dense positively charged area at the center of the atom - called the "nucleus". The positive alpha particles were deflected by the nucleus if they got close enough and thus we have the proton.

atoms have a positively charged central part (nucleus)
electrons are distributed around the nucleus
the mass of an atom is concentrated in the nucleus
compared with the total size of an atom, the size of the nucleus is tiny.

Niels Bohr

27anation — 2025-09-16 17:24:25 UTC

In 1913, a Danish chemist, Niels Bohr developed the next model of the atom. In this model the protons are located in the nucleus and the electrons are located in pathways around the nucleus. The wave mechanical or electron cloud model was introduced in 1926 by Schrodinger & Heisenberg, because of this you cannot predict the location of an electron at given time.

World War I (1914-1918)

27anation — 2025-09-16 17:31:41 UTC

World War I was a global conflict, also called the great war, that lasted from July 28, 1914, to November 11, 1918. It pitted the central powers (primarily Germany, Austria-Hungary, and the ottoman empire) against the allies (including France, great Britain, Italy, and United States). the war resulted in unpredicted destruction and millions of deaths, with the allied powers emerging victorious.

James Chadwick

27anation — 2025-09-16 17:34:49 UTC

James Chadwick discovered the last subatomic particles in 1932. The neutron was so difficult to find because it does not have a charge, it is neutral. Chadwick's discovery earned him the nickname:Jimmy Neutron.