History of the Atom

Democritus

460 BCE

The Greek philosopher Democritus (460-370 B.C.) was the first person to propose the idea that matter was not infinitely divisible. He believed matter was made up of tiny individual particles called atomos. Democritus believed that atoms could not be created, destroyed, or further divided.

Aristotle

384 BCE

Aristotle (384-322 B.C.)
Aristotle is one of the most influential greek philosophers. He rejected the notion of atoms, because it did not agree with his own ideas about nature. One of Aristotle major criticisms concerned that ideas that atoms moved through empty space. Aristotle did not believe that empty space could exist.

Democritus Ideas

370 BCE

Democritus Ideas (460- 370 B.C.)
1. Matter is composed of atoms, which move through empty space.
2. Atoms are solid, homogeneous, indestructible, and indivisible.
3.Different kinds of atoms have different sizes and shapes.
4.Size, shape, and movement of atoms determine the properties of matter.

Aristotle Ideas

322 BCE

Aristotle ideas (384-322 B.C.)
1. Empty Space cannot exist.
2.Matter is made of earth, fire, air, and water.

John Dalton

1766

John Dalton (1766-1844)
A schoolteacher in England, marks the beginning of development of modern atomic theory. Dalton revived and revised Democritus's ideas based on the results of scientific research he conducted.

Dalton's atomic theory

1803

Dalton's atomic theory (1803)
The results of John Dalton's research are known as Dalton's atomic theory,

John Dalton Ideas

1844

John Dalton Ideas (1766-1844)
1.Matter is composed of extremely small particles called atoms.
2.Atoms are indivisible and indestructible.
3.atoms of a given elements are identical in size, mass, and chemical properties.
4.Atoms of a specific element are different from those of another element.
5.Different atoms combine in simple whole-number ratios to form compounds.
6.In a chemical reaction, atoms are separated, combined or rearranged.