The document discusses the organization and structure of the periodic table. It explains that the periodic table is arranged by increasing atomic number and that new rows are added as elements exhibit repeating properties in each column. It then discusses various models that were developed to explain the organization and placement of electrons in atoms, including the Bohr model, quantum mechanical model, electron orbitals, and electron configurations.

1. ORGANIZATION OF THE PERIODIC TABLE November 2 nd , 3 rd & 4th, 2009

2. How is the periodic table arranged? Periodic table is arranged by increasing atomic number How did they decide when to add a new row? A new row is needed so that elements are arranged with repeating properties in each column The properties of the elements repeat periodically Hence… the periodic table! There are many different ways to organize the elements…

3. Circular

4. Long Form

5. Spiral

6. Pyramid

7. Layers

8. Which one do you like the best?

9. Why so many versions? Everybody sees their own pattern in the elements What patterns did we see? Shells Outer Electrons

10. Groups and Families The columns in the periodic table are called groups, or families. Each group has the same number of outer shell electrons Group 1: Alkali Metals Group 2: Alkaline Earth Metals Group 7: Halogens Group 8: Noble Gases

11. Valence Electrons All elements in a group have the same number of outer shell, or valence electrons Valence electrons determine how an element will behave and what it bonds with How many valence electrons does each group have?

12. Typical Charge (Ion Formed) You should remember that 8 is great! Elements will either gain or lose electrons to try to have 8 Elements with 3 or less electrons will LOSE electrons Becoming _____________ Elements with 4 or more will GAIN electrons Becoming _____________ For Hydrogen and Helium, 2 is good too! They can’t possibly hold 8 electrons, so they are full at 2

13. Practice Label: Group name or number # of valence electrons Typical Charge

14. Where are the electrons? -The Bohr Atom Problems with Bohr Model Only worked for Hydrogen Couldn’t explain where the electrons were in atoms that had more than one electron What Bohr got right Energy Levels

15. The difference between continuous and quantized energy levels How do we think energy levels work?

16. Quantum Mechanical Model Electrons do not follow definite paths like the planets Electrons have a probability of being found in a cloud of negative charge around the nucleus. These clouds have specific shapes. There are areas around the nucleus that correspond with certain energy levels (like the Bohr Model) The areas around the nucleus where the electron probably is (energy levels) are called orbitals

17. Orbitals Do not have sharp edges We can never map exactly where an electron is at any given moment All we know is the probability of an electron being in a certain place You know I’m probably in this room all day, you just don’t know if I’m at my desk or in the storeroom or walking around

18. The s Orbital

19. The p orbitals (three of them) The d orbitals (five of them)

20. Relative size of the 1s, 2s, 3s orbitals

21. Electron Filling Electrons like to be close to the nucleus because that requires the least amount of energy Electrons will fill the orbitals in this order: 1s orbital, then 2s, 2p, 3s, 3p, 4s, 3d, and so on. This order can be seen just by looking at the periodic table Larger numbers mean larger orbitals, which means the electrons is farther away from the nucleus The farther away an electron is, the more energy it has Think about where the office of a CEO is…

22. Color in or outline the sections on your blank periodic table to match this diagram

23. Electron Configuration When we write out the location of all electrons in an atom, we are writing its electron configuration Think of it like a map Fill in the missing information on your map Now locate the element with this electron configuration 1s 1 1s 2 2s 1 1s 2 2s 2 2p 4 Write the electron configuration for Boron