The valence electrons are the electrons in the outermost energy level. To find the valence electrons you can write the electron configuration (or the noble gas abbreviation for it), find the sublevel(s) with the highest coefficient, and add up the number of electrons in that sublevel(s). OR you can use the “A” group number to
“count” quickly and the period number to tell which energy level the valence electrons are in. You should know how to do this BOTH ways!
For each of the elements below, write the FULL electron configuration. CIRCLE the part(s) of the electron configuration that have the highest energy level (the VALENCE level), determine the element’s number of valence electrons (# of electrons in the “outermost” shell), and write the “A” group number
Example: Carbon: 1s 2 2s 2 2p 2 4 valence electrons, group 4A
1. fluorine
2. phosphorus
3. calcium
4. xenon
5. iron
6. argon
7. potassium
8. lead
9. silver
10. arsenic
For each of the elements below, write the NOBLE GAS electron configuration. CIRCLE the part(s) of the electron configuration that have the highest energy level (the VALENCE level), determine the element’s number of valence electrons (# of electrons in the “outermost” shell), and write the “A” group number
11. silicon
12. zinc
13. gold
14. iodine
15. oxygen

16. barium
17. aluminum
18. uranium
19. nitrogen
20. nickel
Answer the following questions about valence electrons. LOOK UP THE ANSWERS IF YOU NEED TO!
Valence electrons are important because they help atoms of an element BOND with atoms of another element.
Sometimes, electrons are lost and other times they are gained. Usually, electrons with fewer than 4 valence electrons will lose all of their valence electrons and electrons with more than 4 valence electrons will gain enough to fill in their valence energy level s and p sublevels. Use this information to help you answer the questions below:
1.
Which elements listed above want to lose electrons? List their names, the number of electrons they would LOSE, and give the symbol of the ion they would form including charge. An example is done for you: barium, lose 2 e-, Ba 2+
2.
Which elements above want to gain electrons? List their names or symbols, the number of electrons they would GAIN, and give the symbol of the ion they would form including charge.
3.
Which elements above will likely neither gain nor lose electrons? Explain why these elements are considered stable. To which “A” group number do all of these elements belong?
4.
How many of valence electrons do the elements in group 4A have? Why is it difficult to tell if these elements will gain or lose electrons?