Chemistry - History of Atoms

Proposed that all matter is made up of tiny indivisible particles called atoms.

Democritus

In 1803, proposed the atomic theory of matter.

John Dalton

Concluded the atom had negatively charged particles that he named electrons. Proposed the Plum-Pudding Model.

JJ Thomson

Describes mathematically the wave properties of electrons.

Quantum Theory

His Gold Foil experiment concluded that the atom is mostly empty space with a tiny, positively charged, dense center

Ernest Rutherford

Proposed a model of the atom in which electrons travel around the nucleus in orbits.

Niels Bohr

What did Rutherford conclude from his experiment?

Atoms are mostly empty space with a dense positively charged center.

Which of the following points was included in Dalton's atomic theory, but later found NOT to be true?

atoms of a given element are identical.

Which scientist, or scientists, are credited with the development of the current Quantum Mechanical Model of the atom?

many scientists

How does the current Quantum Model differ from the Bohr Model?

The QM has an e^- cloud, & the BM shows e^- in orbits around the nuclus

Discovered the existence of neutrons.

James Chadwick

This physicist developed an equation that treated electrons as waves.

Erwin Schrodinger

This physicist proposed the relationship between a quantum of energy and the frequency of radiation. E=hv

Max Planck

Discovered oxygen

Josepch Priestley

Discovered radioactivity

Henri Bacquerel

Chemist who known for the Law of Conservation of Mass.

Antoine Lavoisier

Known for the Law of Definite Proportions.

Joseph Proust

This scientist established that the atomic number defines the identity of the element.

Henry Moseley

Used the cathode ray to discover electons in the atom. He is known for the plum-pudding model of the atom.

J.J. Thomson

He suggested that e- be considered waves confined to the space around a nucleus. e^- exist at specific frequencies.

Louis de Broglie

Physisict suggested that EMR has dual wave-particle nature.

Albert Einstein

Developed a principle that states it is impossible to determine simultaneously both the position and velocity of an e^-.

Werner Heisenberg

Suggested that the stucture of atoms is related to electricity.

Michael Faraday

Scientists defined the element as a substance that cannot be broken down into simpler substances by chemical means.

Robert Boyle