1. 13.1 Electrons and Chemical Bonds

2. Valence Electrons
Valence electrons: electrons in the outermost (highest) energy level

3. Valence Electrons – a trick1 7 8 2 3 4 5 6
Look at Group Numbers!

4. How many Valence Electrons?
Nitrogen (N)
Carbon (C)
Potassium (K)

5. Lewis Dot Diagrams To draw a Lewis dot diagram:
A Lewis dot diagram shows the element symbol surrounded by dots representing the valence electrons.
Example:
To draw a Lewis dot diagram:
Determine the number of valence electrons
Write the symbol and add dots for valence electrons

6. Valence Electrons Practice
Now draw the Lewis dot diagrams:
Element Name
Symbol
Number of Electrons
Number of Valence Electrons
Lewis Dot Diagram
Nitrogen
Oxygen
Fluorine
Neon N 7 5 O 8 6 F 9 7 Ne 10 8

7. Lewis Dot Diagrams on PT
Group # = # valence electrons
Transition metals are weird,
ignore for now!

8. Chemical Bonds
Chemical bonds are formed only between the electrons in the highest unfilled energy level.

9. Types of Chemical Bonds
A chemical bond forms when atoms transfer or share electrons.
Covalent Bonds – atoms share valence electrons
Ionic Bonds – atoms transfer valence electrons

10. Dogs Teaching Chemistry!

11. Covalent Bonds
Form between nonmetals
Share electrons

12. Ionic Bonds Form between metal and nonmetal
Electron(s) transferred from metal to nonmetal
Ions are formed
Bond = attraction
Sodium loses an electron and becomes a positively charged ion
Chlorine gains an electron and becomes a negatively charged ion

13. Chemical formulas
A chemical formula tells the ratio of atoms of each element in the compound.

14. Lewis Dot Diagrams EXIT SLIP
Answer the following questions about phosphorous:
How many total electrons does phosphorous have?
How many valence electrons does phosphorous have?
What is the Lewis dot diagram for phosphorous?