1. 13.1 Electrons and Chemical Bonds

2. Chemical formulas
A molecule’s chemical formula tells you the ratio of atoms of each element in the compound.

3. Types of Chemical Bonds
A chemical bond forms when atoms transfer or share electrons.
Covalent bond: the bond formed when atoms share electrons

4. Types of Chemical Bonds
A chemical bond forms when atoms transfer or share electrons.
Ionic bond: the bond formed when atoms transfer electrons to another atom
Ion: an atom that has lost or gained electrons

5. Why do chemical bonds form?
Energy is released when chemical bonds form.
Atoms form bonds to reach a lower energy state.
Reactive: an element readily forms chemical bonds

6. Valence Electrons
Valence electrons: electrons in the outermost (highest) energy level with electrons in it
Chemical bonds are formed only between the electrons in the highest unfilled energy level.

7. Valence Electrons Practice
Complete the chart below:
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

8. Valence Electrons – a trick

9. 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

10. 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

11. 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?