1. Naming and writing Ionic Compounds Chap 7

2. Review What is a chemical formula?
shorthand representation of the composition of a substance using atomic symbols and numerical subscripts

3. Review What is a chemical formula?
shorthand representation of the composition of a substance using atomic symbols and numerical subscripts
can represent a molecule (covalent bonded structure) or a formula unit (ionic bonded structure)

4. Review Significance of a chemical formula
formula tells number and type of atoms in a molecule or formula unit (one atom difference can cause change in properties)

5. Review Significance of a chemical formula Examples: Ag element
NaCl Ionic compound (simple)
Al2(SO4)3 Ionic compound ( w/ polyatomic ion)

6. Writing Formulas Write a formula for potassium sulfide.
STEP 1 Identify the cation and anion.
potassium = K+
sulfide = S2−
STEP 2 Balance the charges.
K S2− K+
2(1+) + 1(2–) = 0
STEP 3 Write the cation first.
2K+ and 1S2− = K2S1 = K2S

7. Writing Formulas STEP 1 Identify the cation and anion.
Write a formula for iron(III) chloride.
STEP 1 Identify the cation and anion.
iron (III) = Fe3+ (III = charge of 3+)
chloride = Cl−
STEP 2 Balance the charges.
Fe Cl−
Cl−
1(3+) + 3(1–) = 0
STEP 3 Write the cation first.
1Fe3+ and 3Cl− = FeCl3

8. Learning Check The correct formula for each of the following is:
A. copper(I) nitride
1) CuN 2) CuN3 3) Cu3N
B. lead(IV) oxide
1) PbO2 2) PbO 3) Pb2O4

9. Solution The correct formula for each of the following is:
A. copper(I) nitride
3) Cu3N 3Cu+ + N3– = 3(1+) + (3–) = 0
B. lead(IV) oxide
1) PbO2 Pb O2– = (4+) + 2(2–) = 0

10. 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

11. Writing Formulas with Polyatomic Ions
The formula of an ionic compound
containing a polyatomic ion must have a charge balance that equals zero (0).
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

12. Learning Check Select the correct formula for each.
A. aluminum nitrate
1) AlNO ) Al(NO) ) Al(NO3)3
B. copper(II) nitrate
1) CuNO3 2) Cu(NO3)2 3) Cu2(NO3)
C. iron(III) hydroxide
1) FeOH 2) Fe3OH 3) Fe(OH)3
D. tin(IV) hydroxide
1) Sn(OH)4 2) Sn(OH) ) Sn4(OH)

13. Solution Select the correct formula for each.
A. aluminum nitrate 3) Al(NO3)3
B. copper(II) nitrate ) Cu(NO3)2
C. iron(III) hydroxide 3) Fe(OH)3
D. tin(IV) hydroxide ) Sn(OH)4

14. Writing Formulas
Remember: you are looking for the smallest whole-number ratio of ions that will give an overall charge of 0 – that’s why the 3rd example has no subscripts ( = 0)

15. Writing Formulas Examples: Fe3+ + Cl1- becomes Al3+ + O2- becomes
Sn2+ + O2- becomes
Mg2+ + (OH)1- becomes
NH41+ + SO42- becomes
FeCl3
Al2O3
SnO
Mg(OH)2
(NH4)2SO4

16. Writing Formulas
Use the criss-cross method – the charges (superscripts) go to the bottom (as subscripts) and switch from right to left

17. Naming Ionic Compounds
Binary ionic compounds
Metal named first
Name of non-metal has –ide added
If metal has more than one possible charge use stock system (Roman numerals) or common name

18. Names of Some Common Ions

19. Learning Check Give the names of the following ions: Ba2+ Al3+ K+
_________ __________ _________
N3 O2 F
_________ __________ _________
P3 S2 Cl

20. Solution Ba2+ Al3+ K+ barium aluminum potassium N3 O2 F
nitride oxide fluoride
P3 S2 Cl
phosphide sulfide chloride

21. Naming Ionic Compounds with Two Elements
To name a compound
with two elements,
identify the cation and anion
name the cation first, followed by the name of the anion

22. Examples of Ionic Compounds with Two Elements
Formula Ions Name
Cation Anion
NaCl Na+ Cl– sodium chloride
K2S K S2– potassium sulfide
MgO Mg2+ O2– magnesium oxide
CaI2 Ca2+ I– calcium iodide
Al2O3 Al S2– aluminum sulfide

23. Learning Check Write the names of the following compounds:
1) CaO ___________
2) KBr ___________
3) Al2O3 ___________
4) MgCl2 ___________

24. Solution Write the names of the following compounds:
1) CaO calcium oxide
2) KBr potassium bromide
3) Al2O3 aluminum oxide
4) MgCl2 magnesium chloride

25. Transition Metals Form Positive Ions
Most transition metals and Group 4(14) metals,
Form 2 or more positive ions
Zn2+, Ag+, and Cd2+ form only one ion.

26. Metals with Variable Charge
The names of transition metals with two or more positive ions (cations) use a Roman numeral after the name of the metal to identify ionic charge.

27. Naming Ionic Compounds with Variable Charge Metals

28. Examples of Names of Compounds with Variable Charge Metals

29. Guide to Naming Ionic Compounds with Variable Charge Metals

30. Naming FeCl2 STEP 1 Determine the charge of the cation from the anion.
Fe ion Cl– = Fe ion – = 0
Fe ion = 2+ = Fe2+
STEP 2 Name the cation by the element name, and use a Roman numeral to show its charge.
Fe2+ = iron(II)
STEP 3 Write the anion with an ide ending. chloride
STEP 4 Name the cation first, then the anion.
iron(II) chloride

31. Naming Cr2O3
STEP 1 Determine the charge of cation from the anion Cr ions + 3O2– = 2Cr ions + 3(2–)
= 2Cr ions + 6– = 0
2Cr ions = 6+ Cr ion = 3+ = Cr3+
STEP 2 Name the cation by the element name, and use a Roman numeral to show its charge.
Cr3+ = chromium(III)
STEP 3 Write the anion with an ide ending. oxide
STEP 4 Name the cation first, then the anion.
chromium (III) oxide

32. Solution Ba2+ Al3+ K+ barium aluminum potassium N3 O2 F
nitride oxide fluoride
P3 S2 Cl
phosphide sulfide chloride

33. Naming Ionic Compounds with Two Elements
To name a compound
with two elements,
identify the cation and anion
name the cation first, followed by the name of the anion

34. Examples of Ionic Compounds with Two Elements
Formula Ions Name
Cation Anion
NaCl Na+ Cl– sodium chloride
K2S K S2– potassium sulfide
MgO Mg2+ O2– magnesium oxide
CaI2 Ca2+ I– calcium iodide
Al2O3 Al S2– aluminum sulfide

35. Learning Check Write the names of the following compounds:
1) CaO ___________
2) KBr ___________
3) Al2O3 ___________
4) MgCl2 ___________

36. Solution Write the names of the following compounds:
1) CaO calcium oxide
2) KBr potassium bromide
3) Al2O3 aluminum oxide
4) MgCl2 magnesium chloride

37. Naming Ionic Compounds
Hydrates
ionic compounds that absorb water into their structures
named like regular ionic compounds, add numeric prefix and hydrate at the end

38. Naming Ionic Compounds
Prefixes:
1: mono-
2: di-
3: tri-
4: tetra-
5: penta-
6: hexa-
7: hepta-
8: octa-
9: nona-
10: deca-

39. Naming Ionic Compounds
Hydrates
ionic compounds that absorb water into their structures
named like regular ionic compounds, add numeric prefix and hydrate at the end
MgSO4  7 H2O, CuSO4  5 H2O

40. Naming Molecular Compounds
Binary molecular compounds
Element from left-most part of table is named first
Name of second element has –ide added
Use Greek prefixes to indicate number of atoms

41. Naming Molecular Compounds
Prefixes:
1: *mono-
(*only with second element)
2: di-
3: tri-
4: tetra-
5: penta-
6: hexa-
7: hepta-
8: octa-
9: nona-
10: deca-

42. Naming Molecular Compounds
Binary molecular compounds
Element from left-most part of table is named first
Name of second element has –ide added
Use Greek prefixes to indicate number of atoms
CO, CCl4, N2O, N2O3

43. Naming Molecular Compounds
Acids
when in water, produce H+ ions, name usually from characteristic anion
Hydro acids: hydro + name of halogen + -ic + acid

44. Naming Molecular Compounds
Acids
when in water, produce H+ ions, name usually from characteristic anion
Hydro acids: hydro + name of halogen + -ic + acid
HCl, HF, HBr

45. Naming Molecular Compounds
Acids
when in water, produce H+ ions, name usually from characteristic anion
Hydro acids: hydro + name of halogen + -ic + acid
HCl, HF, HBr
Oxoacids: polyatomic ion + acid (use –ous and –ic as needed, -ic goes with > # O atoms)

46. Naming Molecular Compounds
Acids
when in water, produce H+ ions, name usually from characteristic anion
Hydro acids: hydro + name of halogen + -ic + acid
HCl, HF, HBr
Oxoacids: polyatomic ion + acid (use –ous and –ic as needed, -ic goes with > # O atoms)
H2SO4, HNO2, HNO3

47. Naming Chemical Compounds
Given: Chemical Formula
Wanted: Name of Compound
Need to ask questions to determine which naming rules to use
Here is one set of questions you could use…