Robert Boyle
- Born 1627 and died 1691.
- Help develop the idea of the element
- A substance was an element unless it could be broken down into two or more simpler substances
- Ex. air could not be an element as the Greek believes because it could be broken down to simpler parts
- Flaws- He held to the idea that metals were not elements because he believed that metals could change due to alchemy.
John Dalton
English scientist and teacher, developed the Atomic Theory
1. Element are made of tiny particles called atoms
2. All atoms of a given element are identical
3. The atoms of a given element are different from those of any other element.
4. Atoms of one element can combine with atoms of other elements to form a compound.
a. A given compound always has the same relative number types of atoms
5. A chemical reaction simply changes the way atoms are grouped together
a. atoms are not created or destroyed in a chemical reaction
1. Element are made of tiny particles called atoms
2. All atoms of a given element are identical
3. The atoms of a given element are different from those of any other element.
4. Atoms of one element can combine with atoms of other elements to form a compound.
a. A given compound always has the same relative number types of atoms
5. A chemical reaction simply changes the way atoms are grouped together
a. atoms are not created or destroyed in a chemical reaction
- Most natural materials are mixtures of pure substances
- Pure substances are either elements or combination of elements called compound
- Law of constant composition :
- A given compound will always contain the same proportion of elements
J. J. Thomson
- A physicist, J.J. Thomson showed in the late 1890s that atoms of any element can be made to emit tiny negative particles.
- Thomson believed that there most be a positive charge to balance the negative charges
- Thomson believed that there was a positive charge cloud with electron scattered to balance the charge
- Created Plum Pudding Model
Ernest Rutherford
- Rutherford, a physicist, discovered that when you hit an atom with an alpha particle, sometime there was a deflection.
- The deflection suggested there was some sort of core to the atom.
- If there was not a core then the alpha particle will go straight through the gold foil