Announcements Tests are not graded Turn labs into basket Mole Party, Mon 10/23 – BRING FOOD! Dates: Stoichiometry Grade Recovery (Friday 10/27) ALL MAKEUP WORK DUE FRIDAY 10/27
What does an atom look like? You all have a sticky note at your seat Think for a few seconds about an atom Draw what you best believe an atom to look like (there is no right or wrong here, just do your best) Stick it on the paper when you finish
History of the Atom
Democritus Around 400 B.C. Atomos indivisible He suggested that all substances in the universe were made up of particles so minute that nothing smaller was possible He regarded those particles as unchangeable and indestructible, and as the only content of the universe
The “Mocker”
Dalton 1803 Atoms = small, dense, spheres Billiard Ball Model Atomic Theory
Dalton’s Atomic Theory All matter is composed of tiny particles called atoms Atoms of the same element are identical Compounds are made with whole number ratios of atoms Atoms are indivisible Chemical reactions occur when atoms are rearranged. The atoms are not changed
Thomson 1897 Discovered the electron, and they were negative Cathode Ray Tube experiment Plum pudding model
Rutherford 1911 Gold Foil Experiment Discovered atom was mostly empty space Discovered the nucleus Dense, positive, small, in center Atomic Model
Bohr 1913 Electrons were located in shells (fixed orbits) Electrons can move to other shells Planetary Model
Millikan 1916 Oil-drop experiment Mass of an electron Exact charge of an electron
Schrödinger 1926 Electron cloud of probability Heisenberg Uncertainty Principle Electron Cloud Model (Modern Model)
Chadwick 1932 Discovered the neutron
History of the Atom http://ed.ted.com/lessons/the-2-400-year-search-for-the-atom-theresa-doud
Models of the Atom Use textbook pg. 128 or internet (just make sure the model you find is accurate) Each square should be neat and have color Dalton Year Model (drawn & labeled) Significance Thomson Year Model (drawn & labeled) Significance Rutherford Year Model (drawn & labeled) Significance Bohr Year Model (drawn & labeled) Significance