2.  Electrons are the negatively charged part of the atom  Electrons are found in orbitals around the nucleus  We write the electron configuration of the element to see the different orbitals the electrons are located in

3.  Write the electron configuration for Lithium…  Write the electron configuration for Fluorine…

4.  The electrons in the last energy level of the element are the VALENCE electrons  The last energy level is the part of the configuration that has the largest number in front of it Lithium = 1s 2 2s 1 Fluorine = 1s 2 2s 2 2p 5

5.  An element can have anywhere from 1-8 valence electrons  The number of valence electrons determines how REACTIVE the element is  8 = totally unreactive  1 and 7 = extremely reactive  2 and 6 = pretty reactive  3-5 = only kinda reactive

6. Pull out your periodic table! You can find the valence electron of the element by seeing what group it is in…. Where are the groups on the periodic table?

7. You should already have groups 1-18 listed on your periodic table Group 1 = 1 Valence Electron Group 2 = 2 Valence Electrons Group 13 = 3 Valence Electrons Group 14 = 4 Valence Electrons Group 15 = 5 Valence Electrons Group 16 = 6 Valence Electrons Group 17 = 7 Valence Electrons Group 18 = 8 Valence Electrons

8.  The transition metals in groups 3-12 have their own set of rules  Don’t worry about them for now

9.  Write down the following elements on a sheet of paper… next to them find out how many valence electrons they have? 1. Neon2. Sodium 3. Aluminum 4. Calcium 5. Sulfur 6. Iodine 7. Carbon 8. Lead 9. Phosphorus 10. Krypton

11.  How many valence electrons does Arsenic have?  How many valence electrons does Potassium have?

12.  To find the number of valence electrons for the elements in groups 1,2 and 13-18 you look at your periodic table  Transition metals (groups 3-12) have their own rules

13.  To find the number of valence electrons for a transition metal you have to write the shorthand electron configuration for that metal  For example… Iron’s shorthand electron configuration is [Ar] 4s 2 3d 6

14.  Just like the regular valence electrons, we look at the highest energy level  Iron’s shorthand electron configuration is [Ar] 4s 2 3d 6 4s 2 = highest energy level  Iron has 2 valence electrons

15.  All transition metals will have a shorthand configuration that gives you 2 valence electrons  However, Transition Metals can act like they have anywhere from 1-4 electrons

16. “Valence Electrons” side of worksheet For each question you should 1. Write the shorthand electron configuration 2. Write how many valence electrons each element has

18.  By now we know that an element can have anywhere from 1-8 valence electrons  We can find the number of valence electrons the element has by looking at the periodic table or by its electron configuration

19.  For Groups 1,2, 13-18 the number of valence electrons depends on group it is in Exception! Helium is a noble gas and is full, but because of its electron configuration it has 2 valence electrons, not 8  Transition metals in groups 3-12 all have 2 valence electrons, even though they don’t always act that way

20.  We can draw Lewis Structures to represent the valence electrons of an element To draw a Lewis Structure 1. Put the element symbol in the middle 2. Determine how many valence electrons it has 3. Draw a dot for each electron around the symbol

21.  As you are putting the dots around the symbol you start by putting one dot on each side of the symbol  No side should ever have more than 2 dots Example: Electron dot diagram for Carbon : C: C

22. Draw the electron dot diagram 1. Put the element symbol in the middle 2. Determine how many valence electrons it has 3. Draw a dot for each electron around the symbol NaClMgAr

23.  “Lewis Dot Diagrams” side of worksheet  Remember, Helium is an exception to the noble gases, it only has 2 valence electrons!