ATOMIC THEORY SCIENTIST

DEMOCRITUS

ATOMOS

• Democritus claimed that everything is made up of atoms.
• He helped to propose the earliest views on the shapes and connectivity of atoms.
• He reasoned that the solidness of the material corresponded to the shape of the atoms involved.

ARISTOTLE

4 NATURAL ELEMENTS

• Believed matter is a mixture of earth, fire, air, and water.
• Was believed for long time
• Is wrong

DALTON

BILLIARD BALL

• Suggested that atoms are the smallest particle of an element.
• That atoms of different elements have different masses.
• They are solid, indestructible units

J.J. THOMSON

PLUM PUDDING

• Discovered electrons
• Atoms: spheres with positive charge random throughout
• No nucleus.

RUTHERFORD

POSITIVELY CHARGED NUCLEUS

• Discovered nucleus
• Discovered alpha beta waves
• Model showed positive charges were centralized

MILLIKIN

MASS/CHARGE OF ELECTRON

• Determined value of charge of an electron
• Based on balancing forces
• Used gravitational force and oil as items in the experiment

CHADWICK

PROTON NEUTRON MODEL

• Discovered the neutron
• Said every element has an atomic number and atomic mass
• He was prisoner in Germany for 4 years