2. Atomic Structure Brought to you by those crazy teachers in... Science II

3. Atom Element Molecule Compound The Basic Analogy Element- Cannot be broken down into another substance Is made up of only one type of atom

4. Molecules & Compounds Analogy: It ’ s like putting two lego blocks together and getting a Cow! (but there are reasons why this happens)

5. So … What ’ s in an Atom?

6. AnATOMy of An ATOM Electron Nucleus with Protons & Neutrons

7. Some Typical Atoms Hydrogen 1P+ 1e- Carbon 6P+ 6N 6e-

8. Rules for Atoms The Net Charge for any atom should equal … 0 This means that there should be the same number of Protons and Electrons! The number of PROTONS defines the element (This is the Atomic Number)

9. More About Atoms The MASS NUMBER of an atom is the sum of the number of PROTONS and the number of NEUTRONS.

10. What happens if... An atom gains or loses electrons? –you get an ION … a charged particle An atom gains or loses neutrons? –you get an ISOTOPE … a heavier or lighter form of the same substance An atom gains or loses protons? –you get a different element (happens in nuclear fission or fusion)

11. Atomic Mass (not Mass Number) Definition: the weighted average of all of the isotopes of an element. What’s a weighted average? –Take carbon for example. You ’ ll notice that the atomic mass is very close to 12. There are heavier forms of carbon, but they occur much less frequently than Carbon 12. If you take the average based on how frequently they occur, the relative amount of Carbon 12 brings the average close to 12.

12. A Little History... Democritus –Greek Thinker (I hope so!) –Atoms are the basic unit which cannot be cut Dalton –1809 - Basic table and symbols Thompson –1890s - A positively charged GOO, with little negative charges floating around in it! -

13. More History (Yippeeee!) Ernie ’ s (Rutherford) Big Adventure Thin Sheet of Gold Atoms

14. Rutherford ’ s Conclusion Atoms are made of mostly EMPTY SPACE! –Actually, the ratio of the size of the nucleus to the diameter of the orbits of electrons can be compared with placing a marble in the middle of a football stadium!

15. Constructing Atoms … An atom has an atomic number of “6”, and a mass number of “14”. –Sketch the Atom Use the 2-8-8 … rule for electron orbitals –Identify the Element (Periodic Table) –Is the atom the most common form for the element? An atom has an atomic number of “14”. Sketch its most common form!

16. Patterns in the periodic table... Sketch the most common form of the first 18 elements (poster size if you prefer). Make a list of any patterns that become obvious to you as you look at the structure of your atoms. Note: Look carefully at the relationship between elements in the same column…or row!

17. Periodic Table Groups Periods

18. Group... Within a Group or Family –Same number of electrons in outer level –React similarly –Are likely to form similar Ions Moving Down a Group –Add one electron shell each time –Elements on the left (Group 1) get more reactive as you go down a column. –Elements on the right (Group 7) get less reactive as you go down a column.

19. Periods... Elements in the same period… –Have the same number of energy levels As you go across a period… –Atomic number increases by “ 1 ” –One electron is added to the outer shell each time –Change in reactivity –Form different types of Ions

20. Who gains? Who loses? In your “Pictorial Periodic Table”, which atoms do you think are most likely to lose electrons? Which are most likely to gain electrons? Make some predictions about the following… Ca, H, Cl, Al, F, Na, K