Atomic Theories

Democritus:

• atoms were indivisible particles
• first mention of atoms
• problems: not testable

Lavoisier:

• law of conservation of mass
• law of define proportions

Proust:

• if a compound is broken down into its constituents the products exist in the same ratio as in the compound

Dalton:

• atoms are solid, indestructibile spheres
• provides for different elements
• based on the law of conservation of mass

Thomson:

• raisin bun model 
• solid, positive spheres with negative particles
• first atomic theory to have positive and negative charges

Rutheford:

• atoms have a positive, dense centre with electrons outside it
• planetary model
• explains why electrons spin around nucleous

-Eva