1. IONIC COMPOUNDS

2. Ionic Compounds:
Form when metals and nonmetals combine by transferring electrons
Metal atoms lose electrons to form positive ions
Nonmetal atoms gain electrons to form negative ions
Electrons are transferred from metal to nonmetal, and the resulting charged particles (ions) form an IONIC BOND

3. Ionic Charges
Determined by the number of electrons in the outermost “shell” – VALENCE
Eg. Aluminum: Al has 13 protons, 13 electrons (2 in first shell, 8 in second, 3 in third)
Al will lose the 3 electrons in the outermost shell and therefore has a valence of 3

4. Formulas for Ionic Compounds:
Eg. Calcium iodide
Write the symbols for elements: Ca I
Write the ionic charges: Ca I 1-
Select the number of ions to balance the charge CaI2

5. Criss-Cross Rule Calcium Iodide 2+ 1- Ca I

6. Nickel and Oxygen Write chemical symbols: Ni O
Determine valence or ionic charges Ni2+ O2-
Use criss cross rule: Ni O
Write formula: Ni2O2
Reduce formula: NiO

7. POLYATOMIC COMPOUNDS
Pure substances involving combinations of metals and polyatomic ions
POLYATOMIC IONS are groups of atoms that tend to stay together and carry an overall ionic charge
Eg. Nitrate NO3-
Eg. Sulfate SO42-

8. Formulas for polyatomic compounds:
Eg. What is the formula for the ionic compound formed by sodium and a hydroxide ion?
WRITE THE SYMBOLS FOR THE IONS: Na OH
WRITE THE CHARGES ABOVE EACH: Na OH
CRISS CROSS CHARGES AND SYMBOLS
WRITE THE FORMULA: NaOH

9. Naming polyatomic compounds:
Combination of the metal and the name of the polyatomic ion
Eg. NaOH sodium hydroxide

10. Determine the formula and name the compound formed by combining calcium and carbonate ion.

11. 2+ 2- Ca CO3- CaCO3 Calcium carbonate

12. MOLECULAR COMPOUNDS
Most of the compounds you encounter everyday do not contain ions. Instead they contain molecules which share electrons to form stable arrangements.
This sharing of electrons is called a covalent bond.
Many nonmetals form covalent bonds.

13. Diatomic Molecules
Certain elements such as oxygen exist as covelently bonded molecules.
The table on p. 202 of your text lists the elements that form diatomic molecules. Copy the information into your notes.

14. Prefixes in Molecular Compounds
Prefix Number Example
mon(o)- 1 CO
di CS2
tri SO3
tetra CF4
pent(a)- 5 PBr5

15. Formulas for molecular compounds:
E.g. What is the formula for a compound formed between carbon and sulfur?
Write the symbols and their combining capacities. Write the one with the larger combining capacity first:
4 2
C S
Criss cross combining capacities to produce subscripts:
C2S4
Reduce the subscripts if possible:
CS2

16. Naming Molecular Compounds:
Molecular compounds containing hydrogen are named as if they were ionic compounds.
eg. H2S hydrogen sulfide
Others have common names such as water (H2O), ammonia (NH3), or methane (CH4).
In general, prefixes are used to count the number of atoms when the same two elements form different combinations.
IF there is only one atom of the first element, the prefix “mono” is not used.
eg. CO Carbon monoxide
eg. CO2 Carbon dioxide