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Drill. Take out HW and place it in the bin Take out your Periodic Table Are the following elements metals, nonmetals, or metalloids?? Calcium (Ca) Arsenic (As) Uranium (U) Chlorine (Cl) Aluminum (Al). Agenda. Drill History of the Atomic Model Video Demos Investigation
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Drill • Take out HW and place it in the bin • Take out your Periodic Table • Are the following elements metals, nonmetals, or metalloids?? • Calcium (Ca) • Arsenic (As) • Uranium (U) • Chlorine (Cl) • Aluminum (Al)
Agenda • Drill • History of the Atomic Model • Video • Demos • Investigation • Exit Slip • HW
I Can… • Create a timeline of the history of the atom • Explain the discoveries (in detail) of Thomson’s and Rutherford’s experiments
What is an Atom? • The basic unit of matter • Latin word – atomos • Means “that which can’t be split” • Not totally true since there are subatomic particles
Working with pico (10-12) • Scanning tunneling microscope
5 Scientists • John Dalton • J.J. Thomson • Ernest Rutherford • James Chadwick • Niels Bohr
John Dalton • England, 1808 • Atomic Theory which states: • All matter is made up of atoms • All atoms of a given element are identical in mass and properties • Compounds are formed with a combination of 2+ different kinds of atoms • A chemical reaction is the arrangement of atoms • Atoms are indivisible and indestructible • **NOTE: Not true today!!
Dalton Model Diagram: Shading is used in the sphere to show that it’s solid throughout.
J.J. Thomson • Demo • In your group… • Look at the data and what you saw in the demo • Determine: • What J.J. Thomson found in the modern-day atom • How J.J. Thomson represented the atom (how its drawn)
Discovery of electrons Cathode Ray Tube Experiment • J.J. Thompson reasoned that if Dalton’s ideas about the indestructibility of an atom were true, how could negatively charged parts of atoms (the electrons) be released from the atom?
J.J. Thomson "There is no other branch of physics which affords us so promising an opportunity of penetrating the secret of electricity.” - J.J. Thomson • England, 1897 • Discovery • Atoms contain electrons
- - + + - + + - + - - + + + - - + + - - + + - + - Thomson Model Diagram • This model is referred to as the ‘Plum Pudding model.’ Thomson believed that the atom consisted of a positive sphere (the pudding) with electrons embedded in it (the raisins).
Blueberry Muffin • Electrons = Blueberries • Positive Charge = “cake” part
Rutherford • In your group… • Look at the data and what you saw in the demo • Determine: • What Rutherford found in the modern-day atom • How Rutherford represented the atom (how its drawn)
Rutherford’s Gold Foil Experiment • Positively charged radiation directed towards a thin sheet of gold foil. • Odd results: most radiation went through the foil, some scattered at wide angles, and some shot back at him!
Ernest Rutherford • New Zealand, 1911 • Discovery • Atoms are made up of mostly empty space • Atoms contain a small, dense, positively-charged nucleus.
- - - - - - - + Rutherford’s Model Diagram
Niels Bohr • Denmark, 1913 • Discovery: • Electrons contain specific amounts of energy and orbit the nucleus in specific paths, called energy levels • Electrons must gain energy to move to a higher energy level or lose energy to move to a lower energy level
e- e- e- Bohr Model Diagram • The small particles in the center represent the protons and neutrons in the nucleus.
James Chadwick • England, 1932 • Discovered the neutron • When looking at the masses of elements, found that they increased, but the electron does not have much weight • Concluded that there must be something else in the nucleus that did not have a charge
Quantum Theory • 1925 – present • Erwin Schrödinger, Wolfgang Pauli, Max Born. Max Planck and Werner Heisenberg Discovery: • Electrons behave more like waves than particles. • The location of an electron is given in terms of probability. The exact location of an electron is impossible to determine • Energy levels exist, but the electrons exist in electron clouds, not in specific paths .
Exit Slip • Please complete the exit slip!
HW • Login to class website • fair.pbworks.com • Take notes on the Periodic Table and color the Periodic Table
Bohr Video • https://www.youtube.com/watch?v=GhAn8xZQ-d8