1. Rules For Writing Chemical Formulas and Naming Compounds-Ionic

2. Binary Ionic Compounds
Binary compound - made of two elements
Oxidation number – tells you how many electrons an atom loses or gains to form an ionic compound; positive or negative; (become stable)
Some metals can have more than one oxidation number

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

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

5. Learning Check Complete the names of the following binary compounds:
Na3N _____________
KBr _____________
Al2O3 _____________
MgS _____________

6. Learning Check Complete the names of the following binary compounds:
Na3N _Sodium Nitride____________
KBr _Potassium Bromide_______
Al2O3 _Aluminium Oxide______
MgS _Magnesium Sulfide_______

7. Transition Metals
Elements that can have more than one possible charge MUST have a Roman Numeral to indicate the charge on the individual ion.

8. 1+ or or 3+
Cu+, Cu Fe2+, Fe3+
copper(I) ion iron(II) ion
copper (II) ion iron(III) ion

9. Examples 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

10. Learning Check
Complete the names of the following binary compounds with variable metal ions:
FeBr2 +2 iron (_____) bromide
CuCl +1 copper (_____) chloride
SnO2 +2 ___(_____ ) ______________
Fe2O3 +3 ________________________
Hg2S +1 ________________________

11. Learning Check
Complete the names of the following binary compounds with variable metal ions:
FeBr2 +2 iron (__II___) bromide
CuCl +1 copper (__I___) chloride
SnO2 +2 _Tin__(__II___ ) _Oxide___
Fe2O3 +3 _Iron (III) Oxide_____
Hg2S +1 __Mercury (I) Sulfide______

12. Writing Formulas
1.Write the symbol of the element or polyatomic ion (ions containing more than one atom) that has the positive oxidation number. Hydrogen and ammonium (NH4) and all metals are positive.

13. Writing Formulas
2. Write the symbol of the element or polyatomic ion with the negative oxidation number. Nonmetals other than hydrogen and polyatomic ions other than NH4 are positive.
3. Use subscripts next to each ion so that the total charge of all ions is zero.

14. Short-cut method: CrissCross
This method ‘criss-crosses’ the ion charges to the subscript position
IF you use criss-cross, be careful to simplify the formula keeping whole numbers!
ex. Na+ (sodium ion) and Cl- (chloride ion)
Na+ Cl Na1Cl1 NaCl
ex. Ca2+ (calcium ion) and O2- (oxide ion)
Ca2+ O Ca2O CaO
(divide both by two to simplify) 1 1

15. Rules for using oxidation numbers to create compounds
Positive ions can only bond with negative ions and vice versa
2. The sum of the oxidation numbers of the atoms in a compound must be zero (the key is to stay balanced)
3. If the oxidation numbers are not equal to zero, then you must add additional elements until they balance at zero.
4. When writing a formula the symbol of the Positive (+) element is followed by the symbol of the negative (-) element.

16. Compounds are neutral For every positive, there must be a negative
Group 1 is + 1
Group 2 is +2
Group 13 is +3
Group 14 is +4
Group 15 is -3
Group 16 is -2
Group 17 is -1
Group 18 is 0

17. Learning Check
What 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

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

19. Polyatomic Ions
NO3-
nitrate ion
NO2-
nitrite ion

20. Polyatomic Compounds
Some compounds like calcium carbonate and copper (II) sulphate do not end in “ide” like other ionic compounds. Why?
Such compounds are pure substances that involve a metal ion and a polyatomic or complex ion.
Polyatomic ions are groups of atoms that tend to stay together and carry an overall charge. E.g. sulphate ion is SO4 -2
Free Template from

21. Free Template from www.brainybetty.com

22. DO NOT have to write but take a look!

23. Writing Formulas for Polyatomic Compounds
What is the formula for copper (II) sulphate
1)      write the symbols for the metal and the polyatomic group
Cu SO4
Free Template from

24. 2) write the ionic charges +2 -2 Cu SO4
Cu SO4
Free Template from

25. 3)   Criss Cross and reduce the subscripts to their simplest terms if possible.
(Brackets) may be needed if there is 2 or more polyatomic ions. Never change the subscript of the polyatomic group.
Cu2 SO42 = Cu2 (SO4)2
= Cu SO4
Free Template from

26. Naming Polyatomic Compounds
The name of the above compound is Copper (II) Sulphate
The name is simply the name of the metal (use a roman numeral if the metal has more than 1 positive charge) and the name of the polyatomic ion . Both can be found on the periodic table by looking them up.
Free Template from

27. Writing Formulas: Polyatomic
Write each ion, cation first. Don’t show charges in the final formula.
Overall charge must equal zero.
If charges cancel, just write symbols.
If not, use subscripts to balance charges.
Use parentheses to show more than one of a particular polyatomic ion.
Use Roman numerals indicate the ion’s charge when needed

28. Examples Sodium Sulfate Na+ and SO4 -2 Na2SO4 Iron (III) hydroxide
Fe+3 and OH-
Fe(OH)3
Ammonium carbonate
NH4+ and CO3 –2
(NH4)2CO3

29. Learning Check 1. Aluminum (III) nitrate
a) AlNO b) Al(NO)3 c) Al(NO3)3
2. copper(II) nitrate
a) CuNO3 b) Cu(NO3)2 c)Cu2(NO3)
3. Iron (III) hydroxide
a) FeOH b) Fe3OH c) Fe(OH)3
4. Tin(IV) hydroxide
a) Sn(OH)4 b) Sn(OH)2 c)Sn4(OH)

30. Learning Check Match each set with the correct name:
Na2CO3 a) magnesium sulfite
MgSO3 b) magnesium sulfate
MgSO4 c) sodium carbonate
2 . Ca(HCO3)2 a) calcium carbonate
CaCO3 b) calcium phosphate
Ca3(PO4)2 c) calcium bicarbonate

31. Mixed Practice!
Name the following:
Na2O
CaCO3
PbS2
Sn3N2
Cu3PO4
HgF2

32. Mixed Up… The Other Way Write the formula: Calcium nitride
Aluminum (III) carbonate
Potassium bromide
Barium fluoride
Cesium hydroxide