Names and Formulas for Ionic Compounds

1
Names and Formulas for Ionic Compounds
2
Types of ions

• Monatomic ion
• ion with one atom
• Mg2 magnesium ion
• Cl- chloride ion
• Polyatomic ion
• ion with more than one atom
• NH4 ammonium
• NO3- nitrate

3
Naming Cations

• Monatomic cation name stays the same
• Sodium, Na goes to sodium ion, Na
• Calcium, Ca goes to calcium ion, Ca 2
• Polyatomic cation - look up in chart
• NH4 ammonium

4
Naming Anions

• The name changes in a monatomic anion
• The ending for a monatomic anion is ______ide
• (like a bride changes her last name)
• chlorine, Cl goes to chloride ion, Cl-
• Fluorine, F goes to fluoride ion, F-
• Polyatomic anion look up in chart
• OH- hydroxide
• SO42- sulfate

5
Question Time

• Given the neutral atom, give the charge and name
  of the monatomic ion that will form. (Look at
  periodic table group numbers for help.)
• Na
• Cl
• Mg
• S
• P

Na
sodium cation
Cl-
chloride anion
magnesium cation
Mg2
sulfide anion
S2-
phosphide anion
P3-
6
Question Time

• Name the following polyatomic ions.
• (use your chart!)
• NH4
• OH-
• SO32-
• SO42-
• CN-

ammonium cation
hydroxide anion
sulfite anion
sulfate anion
cyanide anion
7
Naming ionic compounds

• Name the cation first and then the anion second
  ( then -)
• Example CsF
• Monatomic cations use the element name
• Cs cesium ion
• Monatomic anions change the ending to ide
• F - fluoride ion

cesium fluoride
8
Question Time

• Name the following compounds
• NaBr
• CaCl2
• KOH

sodium bromide
calcium chloride
potassium hydroxide
9
Will these form an Ionic Compound? If so what
will the formula name be?

1. Mg Al
2. Al S
3. Mg O
4. Na N
5. C S

No
two metals
Yes
aluminum sulfide
Yes
magnesium oxide
Yes
sodium nitride
No
two non-metals
10
What will the formula be?

• In ionic compounds, we must balance charges to
  form a neutral compound
• To do that, we crisscross the charges similar
  to find the least common denominator in a
  fraction
• Always reduce to get the formula unit

Ca N
1 2
(2) (2)
1 3
(3) (3)
N3-
(2)
Ca2
(3)
3 6
2 6
Ca6
N6-
Ca3
N2
11
What will the formula be?

• Remember to crisscross the charges
• Al S
• Mg O
• Na N

3
2-
Al2S3
2
2-
MgO
Mg2O2
Not the formula unit Just like fractions, reduce!
1
3-
Na3N
12
Formula Unit

• NaCl versus Na2Cl2
• Formula Unitthe simplest ratio of ions in an
  ionic compound
• How would you write the formula for Sodium and
  Nitrogen?

13
Formula Unit with Polyatomic ions

• Sometimes you will need to use more than one
  polyatomic ion to balance a charge.
• If so, you need to put it in parenthesis (like a
  package) and use a subscript for the multiple
  number
• Ex Mg2 and NO3-
• These charges do not balance so we must
  crisscross them
• Mg1(NO3)2 (we dont need the 1)
• Mg (NO3)2

14
Transition Metal Ions

• Transitions metals will form cations
• Some transition metals only have one ionic charge
• Silver (Ag), Cadmium (Cd2), Zinc (Zn2)
• Some transition metals can take on more than one
  charge.
• Copper (Cu, Cu2)
• Charge is determined from the number of electrons
  lost

15
Naming Transition Metal Ions

• If a transition metal has more than one charge,
  the charge is written as a Roman numeral in
  parenthesis
• Some metals need a middle name
• Fe (iron) has more than one charge 2 and 3
• Fe2 iron(II)
• Fe3 iron(III)
• If the transition metal only has one charge, no
  Roman numeral is needed

16
Naming Ionic Compounds with Transition Metals
Given Fe2O3

• First find the charges of the ions
• Then name the cation followed by the anion
• Iorn(III)oxide
• Try this one Fe3P2
• the charge on iron is a 2
• iron(II) phosphide

17
Question Time

• Name the charge on the transition metal
• copper (II) nitrate
• gold (I) chromate
• Name the compound
• FeO
• Zn(OH)2
• CoPO4

2
1
iron (II) oxide
zinc hydroxide
cobalt (III) phosphate