1. Chemical Formulas and Names for Ionic Compounds

2. Terminology Review:
A chemical formula uses chemical symbols to represent a particular compound.
Compound – 2 or more different elements chemically bonded together in a fixed proportion

3. What are Ionic Compounds?
- when one or more electrons are transferred from one atom to another, creating a neutral compound
- pure substances usually consisting of one metal (donor or giver of electrons – therefore pos. charge) and one non-metal (receiver of electrons – therefore neg. charge)

4. Some Properties of Ionic Compounds:
Crystal Lattice Solid
high melting points
ability to form crystals
dissolve in water to form solutions that conduct electricity
solid at room temperature
Conductivity
Soluble in Water

5. How are Ionic Compounds formed?
Ionic bonds - attraction between oppositely charged ions
How do ions form?
- when one or more electrons move from a metal atom over to a non-metal atom

6. Rules to follow when writing Formulas and Naming Ionic Compounds:

7. (Element symbol and charge)
a) & b) Ion formed from elements
a) Write the symbol for the metal first, then the non-metal.
b) Determine the ion charge each element would form. Write the charge to the upper right of the symbol.
Elements to Combine
a) b)
Ion formed
(Element symbol and charge)
Magnesium
Chlorine
Mg2+
Cl-

8. REVIEW – What’s the Charge?
Remember:
Look at the valence electrons and ask yourself “What’s easiest?”.
Let’s review……….
Note the names of the non-metals when they turn into ions.

9. Predicting Ionic Charges
Group 1:
Lose 1 electron to form 1+ ions H+
Li+
Na+ K+

10. Predicting Ionic Charges
Group 2:
Loses 2 electrons to form 2+ ions
Be2+
Mg2+
Ca2+
Sr2+
Ba2+

11. Predicting Ionic Charges
Loses 3
electrons to form
3+ ions
Group 13:
B3+
Al3+
Ga3+

12. Predicting Ionic Charges
Lose 4
electrons or gain
4 electrons?
Group 14:
Neither! Group 14 elements rarely form ions.

13. Predicting Ionic Charges
Nitride
Gains 3
electrons to form
3- ions
Group 15:
P3-
Phosphide
As3-
Arsenide

14. Predicting Ionic Charges
Oxide
Gains 2
electrons to form
2- ions
Group 16:
S2-
Sulfide
Se2-
Selenide

15. Predicting Ionic Charges
F1-
Fluoride
Br1-
Bromide
Group 17:
Gains 1
electron to form
1- ions
Cl1-
Chloride
I1-
Iodide

16. Predicting Ionic Charges
Stable Noble gases do not form ions!
Group 18:

17. Predicting Ionic Charges
Many transition elements
have more than one possible oxidation state.
Groups :
Iron(II) = Fe2+
Iron(III) = Fe3+

18. Predicting Ionic Charges
Some transition elements
have only one possible oxidation state.
Groups :
Zinc = Zn2+
Silver = Ag+

19. (Element symbol and charge)
c) Determine the number of each ion needed to balance the charge.
Elements to Combine
a) b)
Ion formed
(Element symbol and charge) c)
Balance the charges
Magnesium
Chlorine
Cl-
Mg2+
Mg2+
Cl-
Cl-
Criss-Cross Rule: Place the charge of one ion as the subscript of the other ion.
Total: 2 + and 2 –
Overall charge = 0

20. Write the chemical formula
d) Write the chemical formula Rewrite the symbols together (no spaces) with the number of each needed as subscripts, reduce if possible
Elements to Combine
a) b)
Ion formed
(Element symbol and charge) c)
Balance the charges d)
Write the chemical formula
Magnesium
Chlorine
Cl-
Mg2+
Cl-
Mg2+
MgCl2
Cl-

21. (Element symbol and charge) Write the chemical formula
e) Write the name of the metal first, then the nonmetal by changing the ending to “ide”.
Elements to Combine
a) b)
Ion formed
(Element symbol and charge) c)
Balance the charges d)
Write the chemical formula e)
Name the compound
Magnesium
Chlorine
Cl-
Mg2+
Cl-
Mg2+
Magnesium Chloride
MgCl2
Cl-

22. Polyatomic Ions A polyatomic ion is a group of atoms.
has an overall ionic charge.
Some examples of polyatomic ions are
NH4+ ammonium OH− hydroxide
NO3− nitrate NO2− nitrite
CO32− carbonate PO43− phosphate
HCO3− hydrogen carbonate
(bicarbonate)

23. Naming Polyatomic Ions
The names of common polyatomic anions
end in ate.
NO3− nitrate PO43− phosphate
with one oxygen less end in ite.
NO2− nitrite PO33− phosphite

24. Naming Compounds with Polyatomic Ions.
The positive ion is named first, followed by the name of the polyatomic ion.
NaNO3 sodium nitrate
K2SO4 potassium sulfate
(NH4)3PO3 ammonium phosphite

25. Writing Formulas with Polyatomic Ions.
The Criss-Cross Rule still applies
Na+ and NO3− -> NaNO3
with two or more polyatomic ions has the polyatomic ions in parentheses.
Mg2+ and 2NO3− -> Mg(NO3)2
subscript 2 for charge balance