History of the Atom Flashcards

Flashcards about the history of the atom.

Democritus

A Greek philosopher who formulated the term 'atom' and believed matter could be broken down into its simplest substance.

Aristotle

Dismissed the idea of atoms, declaring matter was made of fire, air, water, and earth.

Dalton

Theorized that all matter is made of indivisible and indestructible atoms.

Thomson

Discovered the electron and proposed the 'Plum Pudding' model of the atom.

Rutherford

Atoms have a small, dense, positively charged center called the nucleus.

Bohr

Electrons orbit the nucleus in different energy levels.

Plum Pudding Model

Proposed that atoms are made from a positively charged substance with negatively charged electrons scattered about.

Nucleus

Positively charged center of an atom.

Modern Cloud Theory

Electrons whirl around the nucleus billions of times per second in an electron cloud.

Bohr Model

The atom model that suggests electrons orbit in different levels.