1. Naming and Formula Writing
IONIC COMPOUNDS
Naming and Formula Writing

2. Monatomic Ions

3. Predicting Charges on Monatomic Ions
KNOW THESE !!!!
Cd+2

4. Naming Positive Ions
Before you name an Ion you have to know the charge
Group 1 = always +1
Group 2 = always +2
Aluminum = always +3
Zinc and Cadmium = always +2
Silver = always +1

5. Naming Positive Ions
With group 1, 2, Al, Zn, Cd, and Ag you just give the name of the atom
Na+ is Sodium
Mg+2 is Magnesium
Ag+ is Silver
Al+3 is Aluminum

6. Naming Negative Ions
All negative ions have their endings changed to –ide
Oxygen becomes oxide
Fluorine becomes Fluoride
Nitrogen becomes Nitride
Chlorine becomes Chloride

7. Formulas of Ionic Compounds
Formulas of ionic compounds are determined from the charges on the ions
atoms ions
    -
Na  +  F  Na F  NaF
   
sodium + fluorine sodium fluoride formula
Charge balance: = 0
 
 
 

8. Writing a Formula
Write the formula for the ionic compound that will form between Ba2+ and Cl
To cancel out Ba’s +2, then two -1 Cl’s are needed!
Solution:
1. Balance charge with + and – ions
2. Write the positive ion of metal first, and the
negative ion Ba2+ / Cl Cl
3. Write the number of ions needed as
subscripts BaCl2

9. Balancing a formula by math
Every ionic compound should have a formula that has a charge that equals zero
Barium Fluoride
Ba+2 F-
How many F ’s are needed to balance Ba+2 ?
Two
So, the Formula is BaF2 -

10. Another way – Drop, Swap, Reduce
What is the formula for Aluminum Oxide?
Al is always +3
Oxide is always -2
Al+3, O-2
DROP: Al3O2
SWAP: Al2O3
REDUCE: 2 and 3 are lowest integers, so leave alone
The Final Formula is Al2O3
Also called “Cris—Cross”!

11. Another example Magnesium Oxide Mg is +2 Oxide is -2 Mg+2, O-2
DROP: Mg2O2
SWAP: Mg2O2
REDUCE: MgO, 2 and 2 divide each other out
The Final Formula is MgO

12. Learning Check
Which is the correct formula for the compounds containing the following ions: 1. Na+, S2- a) NaS b) Na2S c) NaS2 2. Al3+, Cl- a) AlCl3 b) AlCl c) Al3Cl 3. Mg2+, N3- a) MgN b) Mg2N3 c) Mg3N2

13. Solution
1. Na+, S2- b) Na2S 2. Al3+, Cl- a) AlCl3 3. Mg2+, N3- c) Mg3N2

14. CaCl2 = calcium chloride
Naming Compounds
Binary Ionic Compounds:
1. Cation first (+), then anion (-)
2. Monatomic cation = name of the element
Ca2+ = calcium ion
3. Monatomic anion = root + -ide
Cl- = chloride
CaCl2 = calcium chloride

15. Naming Binary Ionic Compounds
Examples:
NaCl
ZnI2
Al2O3
sodium chloride
zinc iodide
aluminum oxide

16. Learning Check
Complete the names of the following binary compounds: Na3N sodium ________________ KBr potassium ________________ Al2O3 aluminum ________________ MgS ________________________

17. Transition Metals
Elements that can have more than one possible charge MUST have a Roman Numeral to indicate the charge on the individual ion 1+ or or 3+ Cu+, Cu2+ Fe2+, Fe3+ copper (I) ion iron(II) ion copper (II) ion iron(III) ion
ROMAN NUMERALS:
I = one
II = two
III = three
IV = four…

18. Names of Variable Ions FeCl3 (Fe3+) iron (III) chloride
These elements REQUIRE Roman Numerals because they can have more than one possible charge:
anything except Group 1A, 2A, Ag, Zn, Cd, and Al
(You should already know the charges on these!)
Or another way to say it is:
Transition metals and the metals in groups 4A and 5A (except Ag, Zn, Cd, and Al) require a Roman
Numeral
FeCl3 (Fe3+) iron (III) chloride
CuCl (Cu+ ) copper (I) chloride
SnF (Sn4+) tin (IV) fluoride
PbCl (Pb2+) lead (II) chloride
Fe2S (Fe3+) iron (III) sulfide

19. Learning Check
Complete the names of the following binary compounds with variable metal ions: FeBr2 iron (_____) bromide CuCl copper (_____) chloride SnO2 _____(_____ ) ____________ Fe2O3 ________________________ Hg2S ________________________

20. Polyatomic Ions Some ions are composed of more then one atom
These are called polyatomic ions
Poly = more

21. Formulas and names Nitrate = NO3- Sulfate = SO4-2 Silver nitrate
Ag+ NO3-
AgNO3
Copper (I) Sulfate
Cu+ SO4-2
Cu2SO4

22. More Polyatomics Lead (IV) Phosphate
Pb+4 PO4-3
Pb3(PO4)4
Notice: When more then one Polyatomic is present you surround it with ()
Notice: The subscripts on Polyatomic ions are NEVER changed

23. Learning Check
Write the correct formula for the compounds containing the following ions:
1. Na+, PO4-3
a) NaPO4 b) Na2PO4 c) Na3PO4
2. Al3+, NO3-
a) Al(NO3)3 b) AlNO3 c) Al3NO3
3. NH4+, N3-
a) NH4N b) NH4N c) (NH4)3N

24. Answers 1. Na+, PO4-3 c) Na3PO4 2. Al3+, NO3- 3. NH4+, N3- a) Al(NO3)3
c) (NH4)3N

25. Polyatomic Ions you have to know
NAME
FORMULA
Acetate
C2H3O-1
Carbonate
CO3-2
Chlorate
ClO3-1
Cyanide
CN-1
Hydroxide
OH-1
Nitrate
NO3-1
Peroxide
O2-2
Phosphate
PO4-3
Sulfate
SO4-2
Ammonium
NH4+1

26. More on Polyatomics Most polyatomic ions end in –ate
The ending –ite means one less oxygen is present then in the ending –ate
Example: Nitrate versus Nitrite:
NO NO2-
NOTICE: Only the number of O’s changed, not the charge!

27. Properties of Ionic Compounds
Ionic compounds are:
also known as salts
They are usually hard and brittle
Conduct electricity when molten or dissolved
Have very high melting and boiling points
Most are soluble in water
Normally composed of at least one metal and one nonmetal