Dalton - 18091. Matter consists of tiny atoms2. Atoms are indestructible3. All atoms of one element are identical4. Atoms of different elements differ inmass and properties5. Atoms combine in whole number ratios
Dalton - 1809Law of Definite Proportions:mass ratios of elements in acompound are always the same,therefore individual atoms of eachelement are all alikeLaw of Multiple Proportions:Atoms always combine in wholenumber ratios (FeS or FeS2, neverFeS1.5) indicating they can’t bebroken apart
Dalton - 1809Limitation:Could not explainwhyatoms ofelements combine in the ratiothey do
Thomson -1897Discovered the electronThought they were in a positivesphere
Rutherford - 1909Gold – Foil Experiment:Shot alpha particles at thin gold foil1/8000 deflected significantly (not what wasexpected, disproved Thomson)Atom mainly empty space with concentratedcharge at center = nucleusVideo:https://LimitationsAll + charges should repelDidn’t account for entire weighte- in motion should continuously give off radiation(light) and lose energy so atoms would implode
Bohr - 1913Energy (light) emitted by excitedelectrons should be continuous, butit’s not!1.