5John Dalton Four points to his theory: All matter is composed of atoms that are indestructible and indivisibleAtoms of one element are all the same; atoms of a different element are different (Au atoms are different from Ag atoms)Atoms cannot be changed into different atoms by chemical of physical changes (Pb atoms cannot be turned into Au atoms)All atoms are like Billiard Balls – a solid, sphereAtoms react in whole numbers
6JJ ThomsonJoseph John Thomson was born in Cheetham Hill, a suburb of Manchester on December 18, 1856.He is given credit for the discovery of the electron.
9JJ Thomson * All gases had the same mass: charge ratio 3 Points to his theory* All gases had the same mass: charge ratio* All atoms contain small, charged particles called electrons* The atom now looked like “Plum Pudding”
10GoldsteinEugene Goldstein was born in 1850 in Germany.
15Millikan All electrons have the same mass 2 Points to his theoryAll electrons have the same massAbout 1/2000 atomic mass unitAll electrons have the same charge-1.6 x CoulombThe atom was still thought to resemble Plum Pudding
16RutherfordErnest Rutherford was born August 30, 1871 in Nelson, New Zealand (one of 12 children)
18Rutherford 3 Points to his theory * Most alpha particle went through = Atom is mostly empty space (area of electrons)* Some alpha particles bounced straight back = atom has a solid mass (nucleus)* Some alpha particles reflected = nucleus is positively chargedNew Model = Nuclear Model
19SchrödingerErwin Schrödinger born August 12 in Vienna, Austria in 1887.
21Schrödinger Major points Electrons do not follow fixed paths They move randomly in areas of probability (orbitals)There are specific energies associated with each orbitalNew Model =Quantum Mechanical Model
22ChadwickJames Chadwick was born in Cheshire, England, on 20th October, 1891.