ATOMS

DEMOCRITUS

ATOMOS THEORY

• First person to propose the atom.
• His theory was not accepted for many years after he created it.
• He proposed that all things are made up of tiny particles called atoms.

ARISTOTLE

EARTH WIND WATER FIRE MODEL

• He proposed that all elements were made up of those componets.
• He didn't belief in the atomic theory.
• He believed in a fifth element called aether.

DALTON

BILLIARD BALL MODEL

• He believed that atoms were like billiard ball.
• Each element had a specific size and weight and were always the same.
• They were solid balls.

THOMPSON

PLUM PUDDING MODEL

• He believed that atoms were electrons held together in positively charged matter.
• He used the cathode ray to find the negatively charged particle called an electron.
• The atom model was held together by its charge.

RUTHERFORD

POSITIVELY CHARGED NUCLEUS

• He used his gold foil experiment to find a positively charged particle.
• Placed electrons around a positively charged nucleus.
• The electrons stayed on a set area.

MILLIKAN

MASS OF AN ELECTRON

• Used his oil drop experiment to find the mass of an electron.
• He used oil because its density was well known and it was more versitile.
• He also helped to determine the charge of and electon.

CHADWICK

PROTON NEUTRON MODEL

• He discovered a particle with a neutral charge called a neutron.
• Neutrons and protons are in the nucleus.
• Electrons orbit in a set path.