Writing and Naming Chemical Compounds

1
Writing and Naming Chemical Compounds
2
Ionic Compounds
3
Review
Common Oxidation Numbers (Charges)

1 2   3 4 -3 -2 -1 0
1 2 3 4 -3 -2 -1 0
Cation- Positive ion that has LOST electrons
(Metals) Anion- Negative Ion that has GAINED
electrons (Nonmetals)
4
Polyatomic Ions you MUST know

• Nitrate NO3-
• Carbonate CO3-2
• Sulfate SO4-2
• Phosphate PO4-3
• Hydroxide OH-
• Acetate C2H3O2- (CH3COO-)
• Ammonium NH4
• Remember polyatomic ions STAY TOGETHER!!!!

5
Bonding Review

• Ionic compounds are formed when a metal transfers
  electrons to a nonmetal
• Cation (metal) Anion (nonmetal) Ionic bond
• Cation (metal) Polyatomic Ion Ionic bond
• Polyatomic ion Anion (nonmetal) Ionic bond
• Polyatomic Ion Polyatomic Ion Ionic bond

6
Writing Formulas for Ionic Compounds

• Rules
• The symbol tells the element and the subscript
  (little number to the right of the symbol) tells
  how many of each element is in the formula
• The cation (metal ion) or positively charged
  polyatomic ion is always written first and the
  anion (nonmetal ion) or negatively charged
  polyatomic ion is always written second

7
Writing Formulas for Ionic Compounds

• 1) Start by writing the cation and anion
  separately with their charges
• Ex If you want to write the chemical formula
  for magnesium and chlorine
• Mg2 and Cl-1
• 2) Criss-cross the charges so that they become
  the subscripts but drop the /- signs
• Ex The 2 charge from Mg will become the 2
  subscript for Cl and the -1 charge from Cl will
  become the 1 subscript for Mg
• Mg1Cl2 (You dont have to write the 1 so the
  formula correctly written would be MgCl2)
• 3) Reduce the subscripts if they can be reduced.
  In this case, they cant, so you are done!!!

8
Now You Try!

• 1) lithium and fluorine
• 2) calcium and sulfur
• 3) cesium and oxygen
• 4) aluminum and oxygen
• 5) sodium and sulfur
• 6) aluminum and chlorine
• 7) potassium and oxygen

9
Check Your Answers

• 1) LiF
• 2) CaS
• 3) Cs2O
• 4) Al2O3
• 5) Na2S
• 6) AlCl3
• 7) K2O

10
Writing Ionic Formulas for Compounds with
Polyatomic Ions

• Start by writing your anion and cation with their
  charges separately
• If your anion or cation is a polyatomic ion,
  place parenthesis around it and put the charge on
  the outside of the parenthesis
• Ex If you are writing the formula for sodium and
  carbonate Na1 and (CO3)-2
• 2) Criss-cross the charges so that they become
  the subscripts but drop the /- signs
• Place the subscript on the outside of the
  parenthesis of your polyatomic ion. MAKE SURE
  NOT TO SEPARATE WHAT WAS INSIDE THE
  PARENTHESIS!!!
• Ex Na2(CO3)

11
Now You Try!

• 1) aluminum and nitrate
• 2) magnesium and phosphate
• 3) ammonium and chlorine
• 4) calcium and acetate
• 5) sodium and hydroxide

12
Check Your Answers

• Al(NO3)3
• Mg3(PO4)2
• (NH4)Cl
• Ca(C2H3O2)2
• Na(OH)

13
Oxidation Number Exceptions

• Since the oxidation numbers of transition metals
  cannot be predicted by looking at the group
  numbers, you will need to memorize the oxidation
  numbers for these exceptions
• Ag1
• Zn2
• Cd2
• Hg22 mercury (I)
• Hg2 mercury (II)

These Roman Numerals will make since in about 3
slides
14
Naming Binary Ionic Compounds

• Binary means there are only two elements in the
  compound
• Rules for Naming
• 1) Name the metal
• 2) Shorten the name of the non-metal and add the
  suffix ide
• Ex KCl would be named potassium chloride

15
Now You Try!

• Name the following compounds
• 1) MgBr2
• 2) NaF
• 3) Al2O3
• 4) CdO
• 5) ZnS
• 6) Na2O
• 7) K3N

16
Check Your Answers

• 1) magnesium bromide
• 2) sodium fluoride
• 3) aluminum oxide
• 4) cadmium oxide
• 5) zinc sulfide
• 6) sodium oxide
• 7) potassium nitride

17
Naming Ionic Compounds with Transition metals

• Since the oxidation numbers of transition metals
  cannot be predicted by looking at the group
  numbers, a roman numeral must be used to name the
  oxidation state of the transition metal in a
  compound
• Transition metals can have more than one
  oxidation number (charge)
• The only exception to this rule is when naming
  the transition metals you were told to memorize
  (silver, zinc, cadmium, mercury still needs a
  roman numeral)
• To find the roman numeral, you must WORK
  BACKWARDS and uncriss-cross your charges!
• Ex FeCl2 uncriss-crossed is Fe2 and Cl-, so
  the Roman numeral when naming iron is (II)
  therefore the name of the compound is iron (II)
  chloride

18
Now You Try!

• 1) SnO
• 2) CuS
• 3) Hg2I2
• 4) CuI
• 5) PbO2

19
Check Your Answers

• 1) tin (II) oxide
• 2) copper (II) sulfide
• 3) mercury (I) iodide
• 4) copper (I) iodide
• 5) lead (IV) oxide

20
So how do you write the formula for a compound
with a transition metal?

• Same process as naming ionic compounds only the
  Roman numeral is the oxidation number, so use it
  as the charge!
• Iron (III) oxide
• EX Fe3 and O-2 is written Fe2O3

21
Now You Try!

• Write the formula for the following compounds
• 1) Tin (IV) chloride
• 2) Lead (IV) oxide
• 3) Tin (II) sulfide
• 4) Mercury (II) bromide
• 5) Mercury (I) fluoride
• 6) Copper (II) nitride
• 7) Iron (II) iodide

22
Check Your Answers

• 1) SnCl4
• 2) PbO2
• 3) SnS
• 4) HgBr2
• 5) Hg2F
• 6) Cu3N2
• 7) FeI2

23
Naming Ionic Compounds with Polyatomic Ions

• Rules for naming
• 1) Name the metal or positively charge polyatomic
  ion first
• 2) If the anion is a polyatomic ion, just name
  the polyatomic ion as is. If the anion is a
  non-metal replace the ending with ide just like
  you would if you had a regular binary compound
• If you have two polyatomic ions, name the
  positively charged poly first followed by the
  negatively charged poly
• Ex Al(NO3)3 would be named aluminum nitrate
• Ex (NH4)Cl would be named ammonium chloride
• Ex (NH4)(NO3) would be named ammonium nitrate

24
Molecular Compounds
25
Review

• Molecular compounds are formed when two nonmetals
  form a covalent bond
• These compounds are called molecules
• Covalent bonds are the result of atoms sharing
  electrons
• Nonmetal nonmetal molecule

26
Naming Molecular Compunds

• We use Greek Prefixes to indicate the number of
  atoms of each element that are present
• 1- mono (not used if for the first element)
• 2- di
• 3- tri
• 4- tetra
• 5- penta
• 6- hexa
• 7- hepta
• 8- octa
• 9- nona
• 10- deca

27
Naming Molecular Compounds

• Rules for naming
• 1) Name the first element using the appropriate
  prefix that indicates how many atoms are present
• If there is only 1 element present you do not
  name it using mono
• 2) Name the second element using the appropriate
  prefix and change the ending to ide
• EX CO would be named carbon monoxide
• EX Cl2O7 would be named dichlorine heptoxide

28
Now You Try!

• 1) CO2
• 2) N2O3
• 3) Cl2O
• 4) SO3
• 5) P4O10

29
Check Your Answers

• 1) carbon dioxide
• 2) dinitrogen trioxide
• 3) dichlorine monoxide
• 4) sulfur trioxide
• 5) tetraphosphorus decoxide

30
Naming Acids

• Compounds which have hydrogen written as the
  cation and have the physical state (aq) written
  next to them are acids
• If any other physical state is noted, (g) (s) or
  (l), the compound is named like a regular binary
  compound
• These compounds are named hydro (nonmetal)ic acid
• EX HCl (aq) is named hydrochloric acid
• If a hydrogen is written in front of a polyatomic
  ion the compound is named (poly)ic acid
• EX H(NO3) (aq) is named nitric acid

31
Now You Try!

• 1) HF (aq)
• 2) H2S (aq)
• 3) H3P (aq)
• 4) H2(SO4) (aq)
• 5) H3(PO4) (aq)
• 6) HBr (l)

32
Check Your Answers

• 1) Hydrofluoric acid
• 2) Hydrosulfuric acid
• 3) Hydrophosphoric acid
• 4) Sulfuric acid
• 5) Phosphoric acid
• 6) Hydrogen bromide

33
Diatomic Elements

• There are 7 elements that cant exist as single
  atoms in nature so they must be written as two
  atoms when they are not combined into compounds
• They are just called by their elemental names
• You must MEMORIZE these
• Hydrogen, H2
• Oxygen, O2
• Nitrogen, N2
• Fluorine, F2
• Chlorine, Cl2
• Bromine, Br2
• Iodine, I2

You can remember these H. BrONClIF