1. Chemical Bonds and Electrons
Chapter 13
Chemical Bonds and Electrons

2. Learning Goals
Infer the relationship between the number of valence electrons and the behavior of atoms.
Compare and contrast ionic and covalent bonding.
Draw Lewis diagrams to represent the valence electrons of atoms.

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

4. Types of Chemical Bonds
A chemical bond forms when atoms transfer or share electrons.
Covalent bond: the bond formed when atoms share electrons
Ionic bond: the bond formed when atoms transfer electrons to another atom

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

7. Valence Electrons Practice
Complete the chart below by determining the number of valence electrons each element has.
Element Name
Symbol
Number of Electrons
Number of Valence Electrons
Nitrogen
Oxygen
Fluorine
Neon N 7 5 O 8 6 F 9 7 Ne 10 8

8. Lewis Dot Diagrams
A Lewis dot diagram shows the element symbol surrounded by one to eight dots representing the valence electrons.
Example:
Draw the Lewis dot diagram by:
Determining the number of valence electrons
Writing the symbol and adding dots