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Atomic Structure

Atomic Structure. Chemistry: Chapter 4. Atoms. Building block of matter. Cannot be seen. Known to exist through indirect evidence. Gathering information w/o actually seeing or touching the object. Used to develop a mental picture or model. Ex. gravity. History of the atom overview.

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Atomic Structure

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  1. Atomic Structure Chemistry: Chapter 4

  2. Atoms • Building block of matter • Cannot be seen • Known to exist through indirect evidence. Gathering information w/o actually seeing or touching the object. Used to develop a mental picture or model. Ex. gravity

  3. History of the atom overview • http://www.nobeliefs.com/atom.htm http://www.chalkbored.com/lessons/chemistry-11/atomic-models-handout.pdf

  4. Greek Model • 2400 years ago, Greek philosopher Democritus • 1st to use the term “atom” meaning “indivisible” or “not to be cut” • Ancient Greeks believed matter was made of 4 basic elements: fire, air, water, and earth

  5. Dalton’s Model • Early 1800’s, English chemist, John Dalton • Meteorologist • Developed the atomic theory • All elements are composed of atoms. • Atoms of the same element are identical. • Atoms of different elements are different. • Compounds are formed by joining 2 or more atoms.

  6. 1897 Thomson’s Model • Proved atoms were made up of even smaller particles • Discovered corpuscles electrons • Model called “plum pudding”

  7. Rutherford’s Model • 1908 • Discovered that atoms have dense, positively charged nucleus • Fired charged particles at gold foil, some went through while others were deflected.

  8. Subatomic particles • Protons • Positively charged; +1 • In the nucleus • Neutrons • No charge • In the nucleus • Distinguishing Characteristics: • Mass • Charge • Location • Electrons • Negative charge; -1 • Outside the nucleus

  9. Atomic Number • Number of p+ in the nucleus • Each element has a certain number of p+ • Also equal to the number of e- Mass Number or Atomic mass • Sum of p+ and neutrons • Mass # = atomic # + neutrons 3 Atomic # Li Chemical symbol 7 Mass #

  10. Isotopes • Atoms of the same element • Have different number of neutrons, but the same number of protons & electrons • They have the same atomic #,but different mass # because of the # of neutrons • Ex. (O-16, O-17, and O-18) Each O has 8 protons, but the neutrons vary

  11. Bohr’s Model • 1913 • Discovered that electrons move in energy levels (orbits) around the nucleus • Called the “solar system model”

  12. Summary of history of the atom • http://www.aasd.k12.wi.us/west/science/bartel/Chemistry/Ch3/History%20of%20Atom%20Notes.pdf

  13. http://www.footprints-science.co.uk/atomicstructure1.htm

  14. Arrangement of electrons • Electrons are in energy levels within an electron cloud. Around the nucleus • 1st energy level can hold 2 e- • 2nd energy level can hold 8 e- • 3rd energy level can hold 18 e- • 4th energy level can hold 32 e- • Each orbital can contain 2 electrons

  15. Electron Configuration • Arrangement of electrons in orbitals • Most stable in the lowest possible energy level • If all electrons have the lowest possible energies, the atom is in ground state

  16. Ex. Magnesium Symbol  Mg Atomic Number  12 # of p+  12 # of e-  12 1st energy level  ____ (can hold 2) 2 2nd energy level  ____ (can hold 8) 8 3rd energy level  ____ (can hold 18) 2

  17. Magnesium 12p+ 12n0

  18. Ex. Aluminum Symbol  Al Atomic Number  13 # of p+  13 # of e-  13 1st energy level  ____ (can hold 2) 2 2nd energy level  ____ (can hold 8) 8 3rd energy level  ____ (can hold 18) 3

  19. Aluminum 13 p+ 14 n0

  20. Ex. Fluorine Symbol  F Atomic Number  9 # of p+  9 # of e-  9 1st energy level  ____ (can hold 2) 2 2nd energy level  ____ (can hold 8) 7 3rd energy level  ____ (can hold 18) none

  21. Fluorine 9 p+ 10n0

  22. Practice Determine the # of e- in the following elements. Draw their electron configuration. Lithium Oxygen Helium Titanium Beryllium Nickel Sulfur Argon Carbon Zinc

  23. Next Lab can be edible • This lab you will be creating a Bohr Model of any atom that you choose beyond Oxygen • You must bring your own supplies for this • All parts of the atom MUST BE REPRESENTED • EX: cookies with icing to hold the P+ N0 and E- in energy levels

  24. Preparing for Lab You will be having a lab where you concentrate on Atomic Structure • Make a list of supplies that you will need in order to make a model of your atom • Bring your supplies to class or drop them by room 604 that morning

  25. After you complete your model… • Once you have completed your model you are to show it to me. • You will need to make a key of what is representative of the protons, neutrons, and electrons. • You are to draw a Bohr model on the same page. • Make a key that show the atomic name, number, symbol and atomic mass number

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