Atom Model Theorys
Dalton's Theory
Background Information
· English chemist born in Eaglesford, England in 1766 and died in 1844.
· Developed his theory to explain the discoveries of scientists in the late 1700s.
· Chemists discovered that they could combine elements to form compounds only in certain fixed proportions according to mass.
· Dalton realized that substances must combine in the same proportions by weight as the weight proportion of their atoms.
· He was the first to calculate the weights of several elements.
Dalton’s theory
1) Elements are made up of small, hard indestructible atoms
2) Atoms of a given element are the same but differ from atoms of different elements
3) Atoms join together to form molecules of the compounds.
4) Chemical reactions do not change the atoms, only how they combine (chemical reactions simply rearrange the atoms)
It explained why a fixed weight of one substance always combines with a fixed weight of another substance in forming a compound.
It explained the law of definite (or constant) proportions.
Each chemical element is composed of its own kind of atoms, all with the same relative weight.
Dalton's Hard Ball Model