Valence electrons & bohr models

1. 9/30/13 Valence electrons & bohr models

2. Atom Structure • Most of the MASS is located in the nucleus • Most of the VOLUME is because of the electron

3. The Bohr Model • A way of showing exactly where all the electrons in an atom are.

4. 10 p 18 p Electron Shells • Orbitals are also called shells 2 p Helium Neon Argon • 1st shell in an atom holds 2 electrons • 2nd shell holds up to 8 electrons • 3rd shell holds up to 8 electrons

5. 6 p 13 p Valence Electrons • Valence electron: an e- in the outermost shell • Determine the chemical properties of an element • The outer shell is called the valenceshell. Only the valence electrons react with other atoms!! Why?? • It’s where the party is at in the atom  4 valence electrons 3 valence electrons

6. Let it out! • Why are valence electrons important for chemical reactions?

7. How many v.e.? • The number of valence electrons (v.e.) is the same as the Group #A • Examples: Ex.1:Hydrogen: Group 1A = _______ v.e. Ex.2:Beryllium: Group 2A = _______ v.e.

8. Practice

9. What patterns can we find??

10. When an electron gets excited: An electron starts in its ground state. If energy is added, the electron jumps to the excited state 1p When the electron returns to ground state, energy is released in the form of light. This is how light bulbs work – the electricity excites the atoms inside the bulb and they give off light as they return to “normal”.

11. Excited State Video…

12. Color and Energy Levels • Each energy level emits a different color

13. WHERE ELSE HAVE WE SEEN COLORED LIGHT COMING FROM EXCITED ELECTRONS?? Fireworks!!

14. Summary • How do you tell the number of valence electrons in an atom?

16. Why do grocery stores organize their food?

17. How does every grocery store organize their food?

18. Periodic Table is like a grocery store…

19. In your groups find 4 patterns in periodic table • You have 3 minutes!