1. Forming Compounds

2. Ionic compounds Most elements like to “hang out” to make them stable
They give up or gain electrons to form compounds so they are less reactive.
Ionic compounds
Always contain a metal and non-metal
The metal atom gives it’s valence electron to the non metal atom
But…how are they held (bonded) together??
Metal
Non-Metal
CATION(positive charge)
ANION(negative charge)

3. The cation and the anion are attracted to each other (this attractions is called an ionic bond
Ionic Bonds are very strong and result in the following properties:
Soluble in water
High melting/boiling points
Conduct electricity when dissolved in water
Hard and brittle
Lattice structure

4. Naming Ionic Compounds:
The name of the metal always comes first, then the non-metal
Change the ending of the non-metal to “ide”
Writing Formulas for Ionic Compounds:
Write the symbol for each element.
Add the charge that each element forms
Criss-cross the number in the charge
Don’t write any 1s in the formula
Reduce the subscripts to lowest terms

5. Example: Write the formula for calcium iodide
Answer: CaI2 (see below)

6. Covalent Compounds Formed between 2 non-metals.
The non-metals share electrons with each other, making each atom “feel” like it has a full shell of its own.
This sharing of electrons results in a covalent bond.
Example: chlorine gas

7. Naming Covalent Compounds:
Because 2 non-metal elements can combine to form more than one stable compound we must use a naming system that distinguishes between them
Step 1 – name the elements in the same order as in the formula
Step 2 – name the second element but change the ending to “ide”
Step 3 – start both words with a prefix to indicate how many of each atom is present in the compound

8. Examples:
NO _______________________
N2O _______________________
NO2 _______________________
N2O3 _______________________
N2O4 __________________________________
N2O5 _______________________
CO2 _______________________
P2O5 _______________________
CH4 _______________________
NH3 _______________________