Deveoping Models of Matter

450 B.C., Four Element Model

200

A man named Empedocles said that matter was composed of four elements, water, air, fire and earth. At this time, greeks believed that these four things made up everything on earth. Empedocles checked his theories exerementally.

350 B.C.

300

a philolsipher named aristotle that believed in empedocles theory "four element" model. He influnced so many peoplel that the " four element" model was eccepted for 2000 years later.

A.D. 500 - 1600

400

for centuries alchemists preformed numbers of experaments to try to make gold from cheap metal such as lead and iron to see if the metal grew like plants turing into gold. they arranged chemical symbols to identify sertain substances that are now recognized as elements and also invented many tools that we use today such as beakers, filters and stiring rods. eventhough they all believed that the "four element " model correct, they never proved it or turned led into gold.

1650

500

An scientist of english decent did not believe in the " four element" model. He arranged a definition for the word element " i mean by element, simple unmigrating bodies" became the definition but today, the modern difinition became a pure substance that cannot be broken down into simpler substances. Robert Boyle aslo didnt believe that air was not an element but a mixture.

late 1700

Mar 13, 600

Joseph Pristley was the first person to scientifically seclude oxygen, but he also did not know that oxygen was an element. the fact that oxygen was an element was determined by Antoine Lavoisier. he experamented with Prestleys oxygen, conculding that was a mixture of two gases, icluding oxygen.

1808

Mar 13, 700

by this time it was accepted that matter was made of elements. john dalton determined a theory of why elements differ from non- elements. John Daltons atomic model for matter said all matter is made of particles that the naked eye cannot see. each element has a differnt kind of atom with its own particle mass, compounds are created when atoms of elements connect to form molecules, and atoms cannot be created dystroyed or subdevidedin chemical changes

1904

Mar 24, 1000

sorrounded by a ring of negative electrons

1904

Mar 24, 1000

J.J. Thomson went over the atomic model even further and revised it. To explain his discovery of very light negative particles, called electrons. he also did experaments where he looked into the topic of beams of much hevier positive particles (later identified as protons). The new model is now known as the raisin-bun model. the model was used to show that the atom is positive sphere with embeded elecrtons. arond the same time a japanese scientist, modeled that same atom as alarge positive spher

1911

Mar 24, 1100

to fireing bullets at a peice of paper and having one of the bullets bounce back. To explain this Rutherfurd had to come up with another model- the nuclear model.

1911

Mar 24, 1100

Ernest Rutherford, working at MaGill university in Montreal, created an experament to test Thomsons and Nagaokas models. He aimed a type of radiation the name of "alpha particles" (positive particles smaller than most atoms) at a sheet of gold foil. He figured, based on the Raisin-bun model, that the particles would pass right throught the gold foil, and the most of them did. Hwever, a very small number of the alpha particles bounced stright back from the foil. He described the rusult as being

400 B.C., Atomic Model

Mar 13, 2001

democritus suggested that matter was made up of tiny particles thaty were unable to be broken down. he called these particles atoms witch means invisible. he figured that differnt elements were made up of differnet kinds of atoms, a very big step in science history witch was not excepted due to that faact that a person in higher power did not accept his concep.

1800s

Mar 2, 2022

eventhough Daltons atomic model cannot descrie why odd thinslike how on a drey winter day you can gat a spark from a doorknob. matter is able to create positive and negative charges, quuantities of electricity that buiild up on an object. a new model was created , introducing small negatively charged particles that can be sperated from their atoms and trosnported to other atoms. in 1831 michael faraday found that electric currents were able to gain electric charges and

1904

Mar 2, 2022

J.J. Tomson altered the atomi model even further, to explain his finding of very light negative particles, called electrons. he also did eperiments with beams of much heavy positve particels . The newer model became known as the ''rasin- bun" model. atoms

1800s

Mar 2, 2022

charged atoms called ions.