1. Covalent Bonds

2. Ionic Bond Review
An ionic bond is the force of attraction between cations and anions that holds ionic compounds together. A bond between a metal and a nonmetal. Ionic bonds form when an atom gains or loses electrons.

3. Oxidation Numbers
The oxidation number is the number of electrons an atom needs to gain, lose or share to become stable. Ions are written by writing the charge of the ion as a superscript after the symbol for the element. Na+1 Cl-1

4. Oxidation Numbers +1 H +2 +3 -4 -3 -2 -1 He Li Be B C N O F Ne Na MgH +2 +3 -4 -3 -2 -1 He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar

5. Covalent Bonds
In covalent bonding, atoms share electrons. Covalent bonds are formed when a nonmetal and a nonmetal share electrons. They form molecules. Molecules are the particles that form because of the shared electrons. They have a neutral charge.

6. Covalent Bonds
Octet rule: Most nonmetals want 8 valence electrons. What nonmetal is the exception?
Hydrogen ● H O

7. Covalent Bonds
Covalent bonds form molecules. Just like in ionic bonding, these molecules have chemical formulas that describe the proportions of the different elements in the compound. Subscript numbers – how many atoms of that element are in one unit of the compound. Coefficients – how many molecules there are.

8. Chemical Formulas
4H2O
Coefficients are normal size and in front of formulas.
Subscripts are small and after/below elements in the compound

9. Chemical Formulas
4H2O
This formula stands for 4 molecules of water, each molecule of water has 2 atoms of hydrogen and 1 atom of oxygen.

10. Covalent Bonding Rules
Only bond the unpaired electrons.
2. Most nonmetals want an octet. ● ● O ● ● ● ●

11. Covalent Bonding Rules
Always start with the atom that makes the most bonds.
You may need double or triple bonds.
Atoms
F and H O N C
# of Bonds 1 2 3 4