Atomic History & Atomic Structure!
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Transcript of Atomic History & Atomic Structure!
Atomic History & Atomic Structure!• Notebook Add-ons:– P. 22: Unit 1 Test– P. 23: “Unit 2 Key Terms”– P. 24: “Unit 2 Proficiency Tracker”– P. 25: “Atomic Theory Timeline” Chart– P. 26: Periodic Table– P. 27: Title: “Notes: Atomic Structure– P. 28: “Atomic Structure Chart”
• Homework!– Finish “Atomic Structure Chart”– Study for Quiz!!!– Start working on your Project! (Due 9/30)
Mystery Box
• With your table group… try to figure out what is inside the “Mystery Box”
• DON’T OPEN IT!!!!
• How small is an atom???• http://www.youtube.com/watch?v=aQnbF-zp
DiM
Atomic Theory
• Discuss with your table groups your research findings on your scientist.
Atomic Theory Timeline
Fill in your chart!
John Dalton (1803)
Dalton’s Postulates
1) All elements are composed of tiny indivisible particles called atoms.
2) Atoms of the same element are identical. The atoms of any one element are different from those of any other elements.
3) Atoms of different elements can physically mix together or can chemically combine with one another in simple whole-number ratios to form compounds.
4) Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction.
Dalton’s Postulates
• We now know that certain parts of this theory are invalid.
• Part 1 – False. Atoms have been split.• Part 2 – Partially False. Some atoms of the
same element have more neutrons. (However, atoms of different elements are different.)
• Part 3 – True!• Part 4 – True!
Dalton’s Model
• Just a tiny ball with no parts inside
J. J. Thomson (1897)
J. J. Thomson• Used a cathode ray tube to shoot an electrical
charge through it.• Saw that the particles were deflected towards
the positive end of the tube.– This must mean that atoms contained a NEGATIVE
charge!• Discovered the ELECTRON.
http://www.youtube.com/watch?v=IdTxGJjA4Jw
http://www.youtube.com/watch?v=RW_zfKOU9uM
Thomson’s Model
• “Plum Pudding” or “Chocolate Chip Cookie Dough” Model.
• A ball of positive charge containing a number of electrons.
Ernest Rutherford (1911)
Ernest Rutherford
• Did the Gold Foil Experiment– Shot alpha (positively charged)
particles at a sheet of gold foil.• Saw that most particles passed
through the foil and some deflected straight back at different angles.
• Means that atoms are mostly empty space but contain a densely packed positive center….– Discovered the NUCLEUS
http://www.youtube.com/watch?v=wzALbzTdnc8&NR=1
http://www.youtube.com/watch?v=5pZj0u_XMbc
Rutherford Model
Nucleus
Empty Space
Electrons
Dense, positively charged nucleus
Surrounded by electrons (mostly empty space)
Niels Bohr (1913)
Niels Bohr
• Electrons travel in definite orbits around the nucleus
• Electrons are found in “energy levels”• AKA Planetary Model
http://www.youtube.com/watch?v=wCCz20JOXXk
Bohr Model
Nucleus
Electrons(orbiting the
nucleus)
Atomic Structure
p. 27
Proton
Neutron
Electron
particle Symbol Relative Mass
Charge Location
Proton p+ 1 +1 Nucleus
Electron e- 0 -1 Electron cloud
Neutron n0 1 0 Nucleus
Element Info on the Periodic Table
Element Name
Atomic Number (#protons)
Element Symbol
Atomic Mass
Other Info
• Mass Number = #p + #n• NOT the same as Atomic Mass… you
CAN’T find this on the P.T.!• # of electrons: – If #of electrons is the same as the # of
protons --- NEUTRAL ATOM– If the # of electrons is NOT the same as
the # of protons --- ION
Beans activity
• A Carbon atom has:– 6 protons– 6 neutrons– 8 electrons
• Create a “bean atom” of carbon.
Atomic Symbols
6C12 2-
Mass Number (#protons + #neutrons)
Charge (#protons - #electrons)
Atomic Number (#protons)