1. Ionic Compound
A compound made up of one or more positive metal ions (cations) and one or more negative non-metal ions (anions)
Most ionic compounds have:
High melting points
are hard and brittle
Form electrolytes (conduct electricity) when dissolved in water to form solutions

2. Formation of Sodium Chloride

3. Chemical Formula of an Ionic Compound
Step 1: Write the symbols of the elements, with the metal on the left-hand side and the non-metal on the right-hand side.
Mg Cl
Step 2: Add the ionic charge of each ion above the symbol
+2 -1

4. Step 3: Determine the number of ions required to bring the charge to zero.
1(+2) + 2(-1) = 0
Mg O
Step 4: Write the chemical formula using the (red) coefficients in front of each bracket as subscripts
Mg1Cl2 Note: Do not write the subscript “1”
The chemical formula for magnesium chloride is MgCl2

5. Crisscross Method
Step 1: Write the symbols of the elements and their ionic charges
Mg 2+ Cl-
Step 2: Crisscross the numbers of the ionic charges so that they now become subscripts
MgCl2

6. Considering Multiple Ionic Charges
Write the chemical name of CuBr2. Note that copper could have either of two ionic charges (+1 or +2).
Each bromide ion has a charge of -1, so the total charge of bromide ions is 2(-1).
The ionic charge of copper in this compound is +2
Roman numerals are included ONLY if the metal has more than one ionic charge.
The name of CuBr2 is copper (II) bromide

7. MOLECULAR COMPOUNDS
Nitrogen dioxide, NO2 , is the gas responsible for the reddish-brown colour of smog
Inhaling nitrous oxide, N2O , helps dental patients relax

8. Most of the chemicals we encounter are molecular compounds, including:
Acetylsalicylic acid, or Aspirin
sugar
water

9. Soft Drinks
Sugar
C12H22O11
Carbon Dioxide
CO2
Water
H2O

10. Living Organisms
Make thousands of different kinds of molecular compounds
Sugars, fats, and proteins are all molecular compounds
Some of them are very large, containing thousands of atoms in a single molecule

11. Molecular Compounds The majority of all known compounds are molecular
Molecules consist of two or more non-metal atoms joined by a covalent bond
A COVALENT BOND forms when atoms share electrons
The chemical formula gives the exact numbers of atoms in each molecule
Diatomic molecules consist of only two atoms of either the same or different elements

12. Ionic Bond vs Covalent Bond
An Ionic bond is the simultaneous strong attraction of positive ions and negative ions
A covalent bond results from the sharing of outer electrons between non-metal atoms

13. Naming Molecular Compounds
Prefixes indicate how many atoms of each element are present (for example, dinitrogen pentoxide, N2O5)
If there is only one atom of the first element, the prefix “mono” is omitted
The name of the last element ends in “ide.”
Prefix
Number of Atoms
Mon(o)- 1
Di- 2
Tri- 3
Tetra- 4
Penta- 5

14. Writing Formulas of Molecular Compounds
Sulfur dioxide
SO2
Prefixes in the name become the subscripts in the formula

15. Hotdogs contain many chemical additives
Sodium nitrite
Preservative and colour enhancer
Sodium phosphate
Binding agent
Sodium erythrobate
Preservative

16. Nitrites are not all bad news ...
Research suggests that sodium nitrite may help protect heart tissue after a heart attack or heart transplant
Nitrites and nitrates occur naturally in soil and are important plant nutrients

17. Polyatomic Ions Phosphate Ion
A polyatomic ion is an ion that consists of a stable group of several atoms acting together as a single charged particle.
The ionic charge of a polyatomic ion is shared over the entire ion rather than being on just one atom
Phosphate
Ion

18. Formulas and Charges of Common Polyatomic Ions
Name of Polyatomic Ion
Ion Formula
Ionic Charge
Nitrate ion
NO3-
- 1
Nitrite ion
NO2-
Hydroxide
OH-
Carbonate
CO32-
- 2
Sulfate
SO42-
Phosphate
PO43-
- 3
Ammonium
NH4+
+ 1

19. Naming Compounds involving Polyatomic Ions
Write the name of the compound Fe(NO3)3 Step 1: Write the name of the metal and check whether it has more than one possible ionic charge. Iron has two possible charges (+2 and +3) Step 2: Determine the ionic charge of the metal. Fe(NO3)3 x + 3(-1) = 0 x = + 3 Step 3: Write the name of the compound with the Roman numeral if necessary. The name of Fe(NO3)3 is iron (III) nitrate.

20. Writing Formulas for Compounds Containing Polyatomic Ions
What is the chemical formula of copper (II) nitrate? Step 1: Write the symbol of each ion, with its charge. Cu2+ (NO3)- Step 2: Crisscross the numbers of the ionic charges so that they become subscripts. Cu2+ (NO3)- Step 3: Write any necessary subscripts after the brackets around each ion. The formula of copper (II) nitrate is Cu(NO3)2

21. What is the most common ending for the name of ....
A) a polyatomic anion?
“ –ate” (nitrate, chlorate, sulfate, phosphate)
B) an anion made up of only one element?
“ –ide” (nitride, chloride, sulfide, phosphide)