Matter timeline.

A Greek scholar named Empedocles, came up with the idea that matter was made up of the four elements; fire, water, earth and air. Those elements mixed together in different ways to make up different substances. Empedocles experimented with some of his theories to see if they worked. He showed that even though we can not see air it's not just non-existent.

Democritus, another Greek, came up with the idea that matter is made up of little particles that couldn`t be broken down any more. He named the particle, atoms after the greek word atomos which means “invisible”.This caused the idea that elements were made of different kinds of atoms, which was an incredible thought at the time. Although, Democritus` ideas were rejected because Socrates, a very influential figure in that time, wouldn't accept them.

Aristotle, a philosopher, believed in the Empedocles theory of the “four elements” regardless of the fact of the more recent atomic theory. Aristotle had such a grand influence, many people read his writings, that Empedocles theory was accepted for nearly 2000 years.

Lots of alchemists believed that medals grew similar to plants becoming gold when ripe. For many years alchemists tried to make gold from experimenting on cheap metal like iron and lead. They created chemical symbols for substances which we now know as elements and compounds. They also made tools that we use today in our labs beakers, stirring rods, distillation apparatus and filters. Despite finding new substances, they still followed the four element theory.

Robert Boyle, an english scientist, did not believe in the four element theory. He came up with a new definition of element; “I mean by element, simple unmitigated bodies.” This then was considered the modern definition of an element; a pure that cannot be chemically broken down into simpler substances. Also Boyle believed that air was a mixture rather than an element.

The first person to isolate oxygen scientifically was Joseph Priestley, although he had no knowledge that oxygen is an element. This was recognized by Antoine Lavoisier. Using Priestley's oxygen, Lavoisier experimented and concluded that air was a mix of two or more gases, one that was oxygen.

Meanwhile, Henry Cavendish was experimenting with acid and metal which made a flammable gas that was lighter than air. The gas he prepared was Hydrogen but he did not know that, but learned that his gas would burn in contact with Priestley's oxygen, making water. Before that scholars thought that water was an element.

At this time the main concept was that matter was made of elements, both theories had merged. John Dalton published a theory on why elements differ from each other and non-elements.His theory for matter said that;All matter is made of atoms which are particles too small to be seen,each element has its own atom with its own particular mass,compounds are created when atoms of different kind fuse together to make molecules,and atoms can not be created, destroyed or subdivided in chemical reactions.

Even so Dalton's theory cannot explain why on a dry winter day if you touch a metal doorknob you can get a spark. Matter can blossom positive or negative energie. A new model was introduced stating that tiny negatively charged particles that could be separated from their atoms and switched to another atom.

In 1831 Michael Faraday discovered that an electric current could produce chemical changes in some compounds in some solutions. The atoms could get an electric charge making charged atoms called ions. This different version of Dalton's theory is; Matter must contain positive and negative charges, Opposite charges attract and like charges repel, and atoms combine to form molecules because of electrical attractions between them

H. Nagaoka modeled the atom as a large positive sphere surrounded by a ring of negative electrons.

The atomic model was further revised by J.J Thomson to explain his findings of very light negative particles named electrons. Also he experimented with heavier positive energie beams. His new model became known as the “raisin-bun” model; atoms contain particles called electrons, electrons have a small mass and a negative charge,the rest of the atom is a sphere of positive charge, the electrons are embedded in this sphere so that the resulting atoms are neutral or uncharged.

Ernest Rutherford tested Thompson’s and Nagoaka’s models out by aiming a type of radiation called alpha particles at a thin sheet of gold foil. He predicted based on Thomson's model that the particles would go through the gold foil, as most of them did. Although a few of the alpha particles bounced back from the gold foil. Ernest was in awe, he depicted it as being similar to shooting bullets at a kleenex and having 1 come back at you.

In order to explain what happened Rutherford had made a new model, the nuclear model; an atom has a tiny, dense, positive core called the nucleus and the nucleus is mainly surrounded by void space, containing fast moving negative electrons.

Matter

450 B.C.

400 B.C.

350 B.C.

A.D 500 -1600

1650

Late 1700s Part 1

Late 1700s Part 2

1808

1800s

1800s (Pt 2)

1904 (Pt 2)

1904

1911

1911 (Pt2)