1. Making Molecules and Compounds
Bonding
Making Molecules and Compounds

2. What’s the difference between a molecule and a compound?
All compounds are molecules, but not all molecules are compounds.
A compound is a molecule that has at least 2 DIFFERENT elements.
Some molecules are made of the same element and are not compounds.
FOR EXAMPLE: H2 02 N2

3. Two Types of BONDING COVELANT SHARE ELECTRONS TWO NONMETALS IONIC
GAIN AND LOSE ELECTRONS
METAL AND A NONMETAL

4. IONIC OR COVALENT?
COVALENT
CO2
NaCl
HBr
MgCl2
IONIC
COVALENT
IONIC

5. Why do atoms bond? Atoms bond to become more stable.
Stable = 8 Valence electrons
Noble gases don’t bond naturally because their valence shells are already full.

6. Ionic Bonding Only ions of opposite charges will bond.
Oxidation Number or Charge
Na Cl-1
Only ions of opposite charges will bond.
Metals will only bond with Nonmetals

7. Rules of Bonding
If they have the same number – they will cancel out. (+1, -1; +2, -2; +3, -3) Mg+2 S-2 would be MgS
If they do not cancel out, use the criss-cross method…
Ca Cl CaCl2
3. We do not write 1’s in chemical formulas. If the element’s symbol is there. We know there is only one if it doesn’t have a subscript.

8. Counting Atoms in Molecules
SUBSCRIPTS ONLY APPLY THE ELEMENT IN FRONT OF IT. THEY DO NOT APPLY TO ELEMENTS BEHIND THE SUBSCRIPT.
H2O
The “2” means there are 2 Hydrogen. There is only one Oxygen.