1. 4.2 – Ionic and Covalent Compound Naming
Ionic Compounds: - are made up of positive and negative ions arranged in a crystal structure. (metal and non-metal) Covalent Molecules: - are made up of atoms sharing electrons. (non-metal and non-metal)
Salt, NaCl
Water, H2O

2. Naming Ionic Compounds:
name of an ionic compound = positive ion negative ion-ide
Ex.1: magnesium and oxygen
positive ion negative ion-ide
Magnesium ox + ide
Magnesium oxide
Ex.2: what is the name of Ca3N2?
Ca = calcium; N = nitrogen
Drop the end of the negative ion and add –ide
Calcium nitride
Ex.3: What is the name of BaCl2?
Barium chloride
Magnesium oxide is used as a drying agent.

3. Writing formulas for Ionic Compounds
Remember: positive charges must = negative charges
Ex.1: What is the formula for magnesium phosphide?
Magnesium is Mg2+ Phosphorous is P3–
Lowest common multiple of 2 and 3 is 6
3 Mg2+ ions & 2 P3– ions (6 +ve’s & 6 –ve’s)
Magnesium phosphide = Mg3P2
Ex.2: What is the formula for calcium oxide?
Calcium is Ca2+ Oxygen is O2–
1 Ca2+ ion & O2– ion
Calcium oxide = CaO

4. Drawing Formula Diagrams
More Examples:
Lithium nitride
Barium sulphide

5. Ionic Compound with a Multivalent Metal
Multivalent: some transition metals have more than one charge.
Roman numerals are used after the metal name to indicate which ion was used
Ex. 1 What is the formula manganese(III) sulphide?
This manganese is Mn3+ Sulphur is S2–
Lowest common multiple of 3 and 2 is 6
2 Mn3+ ions and 3 S2– ions
Mn2S3

6. You try! Titanium can be Ti4+ or Ti3+ Fluorine is F–
What is the name for TiF4?
Titanium can be Ti4+ or Ti3+ Fluorine is F–
From the ratio in the formula you can find out it is Ti4+
1 Ti4+ ion and 4 F– ions
Titanium (IV) fluoride

7. Provincial Exam Question

8. Polyatomic Ions
are made up of several atoms joined together by covalent bonds
The whole group has a + or – charge, not individual atoms.
Ex.1 What is the formula of sodium sulphate?
Na+ and SO42–
Na2SO4

9. Ex.2: What is the name of the compound KClO?
K+ = potassium ClO– = hypochlorite
Potassium hypochlorite
Ex.3: What is the formula for Calcium nitrate?
Ca and NO3-
Ca(NO3)2
* Note the brackets around NO3 show there are two of the nitrate ions present

10. Provincial Exam Question

11. Naming Simple Covalent Compounds
Prefixes are used before the atom name to indicate the number of atoms in the molecule.
Examples:
CO = carbon monoxide
CO2 = carbon dioxide
Write the most metallic atom (furthest left) first, then add -ide to the end of the second atom’s name

12. Examples: Trisilicon hexaphosphide
What is the name of the molecule Si3P6?
Trisilicon hexaphosphide
What is the chemical formula for the molecule trinitrogen tetrachloride?
N3Cl4

13. Provincial Exam Question

14. How do you know which type it is?
To determine whether a compound is ionic or covalent:
- Examine the formula
Ionic compounds start with a metal or the ammonium ion
Covalent compounds start with a non-metal
Take the Section 4.2 Quiz