1. Naming Compounds and Writing Formulas
Chapter 4
Ionic compounds, polyatomic ions and Covalent compounds, Acids

2. Ban DHMO? DHMO is dihydrogen monoxide.
Evaluate the following link and decide if this potentially dangerous chemical should be prohibited.

4. How do you name binary ionic compounds
How do you name binary ionic compounds? (composed of two elements – a metal and a nonmetal)
Name the first ion
Name the second ion changing the suffix to –ide.

5. Name the nonmetal ion, changing the suffix to –ide.
Examples
NaCl
What is the name of this compound:
HIJKLMNO?
WATER – “H” to “O”
You have to admit – that was funny!
Name the metal ion
Sodium
Chloride
CaO
Name the nonmetal ion, changing the suffix to –ide.
Calcium
Oxide
Al2S3
Aluminum
Sulfide
MgI2
Magnesium
Iodide
BaNa2
You should recognize a problem with this one
The name of this is Banana (JOKE – haha)
This is two metals – not a binary ionic compound

6. Notice – metal and nonmetal.
What about the transition metals and using roman numerals? How does that work? Let’s see.
FeO
Notice – metal and nonmetal.
Name the first ion. Since the first ion is a transition element, you must use a Roman Numeral to represent the charge.
Iron II
Oxide
How do you know the charge?
Deductive reasoning.
All compounds are neutral.
Oxygen has a -2 charge (group 16)
Therefore ….. Iron must have a +2 charge since there is one iron and one oxygen. Iron gets a Roman Numeral II.
Isn’t this easy and FUN!!!

7. Cu2S
Name the first ion. Since it is a transition metal, you must use a Roman Numeral.
Which Roman Numeral? The Roman Numeral is the same as the charge of the ion.
How do you find the charge?
Deductive reasoning!
All compounds are neutral
Sulfur has a -2 charge (group 16)
There are two coppers.
Therefore each copper must have a +1 charge for all ions to be neutral
Copper I
Sulfide

8. Another Example: MnO2
Name the first ion. Since it is a transition metal, you must use a Roman Numeral.
How do you determine the Roman Numeral?
It is the same as the charge.
What is the charge of Mn?
All compounds are neutral.
Oxygen (group 16) has a -2 charge.
There are two oxygens and one Mn.
Therefore Mn must have a +4 charge for this compound to be neutral.
Manganese IV
oxide

9. So why must we use Roman Numerals with transition elements?
The metals in groups 1, 2, and 13 have single, definite charges.
Group 1 metals have a +1 charge.
Group 2 metals have a +2 charge.
Group 13 metals have a +3 charge.
Transition metals may have multiple charges – usually two different positive charges.
For example, there are two copper oxide compounds:
CuO
Copper II oxide
Copper is +2
Cu2O
Copper I oxide
Copper is +1
Cu2O and CuO
We can’t just say Copper oxide. Which one of these is Copper oxide? We must distinguish these by using a Roman Numeral

10. You need to remember the charges for these.
There are three transition elements which do not require a Roman Numeral because they have single definite charges. These are
Zinc – Zn+2
Cadmium – Cd+2
Silver – Ag+1
You need to remember the charges for these.
No Roman Numerals needed for these.
Ag2O
Name the first ion.
Name the second ion changing the suffix to –ide.
Silver
oxide
ZnCl2
Name the first ion.
Zinc
chloride
Name the second ion changing the suffix to –ide.

11. How do you write formulas for binary ionic compounds given the name?
Two simple steps:
Write the symbol and charge of each ion
Balance the charges by providing subscripts
Magnesium chloride
Write the symbol and charge of each ion.
Mg Cl-1
Cl-1
Balance the charges by supplying subscripts. Subscripts tell how many of each atom is present.
MgCl2
You need a second Cl-1 to balance the charges

12. FeBr3 More examples: Iron III bromide
Write the symbol and charge of each ion. The charge of the iron is provided by the Roman Numeral.
Fe Br -1
Br -1
Br -1
FeBr3
Balance the charges by supplying subscripts. The subscripts tell how many of each ion is needed to balance the compound.
You’ll need three bromine ions to balance the one iron.

13. Al2S3 Aluminum Sulfide Write the symbol and charge of each ion.
Balance the charges by supplying subscripts.
S-2
In this case the charges do not evenly divide into each other. You must find the least common multiple. SIX
Al2S3
How many aluminums are needed to arrive at a +6 charge? 2
How many sulfurs are needed to arrive at a -6 charge? 3

14. Second Category of compounds – Ternary Ionic Compounds
Second Category of compounds – Ternary Ionic Compounds. These compounds contain at least one polyatomic ion.
What is a polyatomic ion?
Let’s look at the name to try to understands.
It is an ion – that means it has a charge.
It is polyatomic – that means it is made of more than one atom.
Simple as that!!
Let’s look at some examples of polyatomic ions.

15. CO3-2
carbonate
This ion is composed of one carbon and three oxygens and the entire group has a charge of -2.
Polyatomic ion – Group of atoms that act as a unit and carry a charge.
More examples:
PO4-3
Phosphate
C2H3O2-1
Acetate
SO4-2
Sulfate
OH-1
Hydroxide
SO3-2
Sulfite
NO3-1
Nitrate
ClO4-1
Perchlorate
NO2-1
Nitrite
ClO3-1
Chlorate
NH4+1
Ammonium
(only positive PI)
You need to learn these!!!

16. Polyatomic Ion s How do you recognize Ternary Ionic Compounds?
Composed of two ions in which at least one is a polyatomic ion.
There is only one positive polyatomic ion (NH4+1)
Three possible types of Ternary Ionic Compounds:
Ammonium + negative ion (nonmetal)
Metal (positive ion) + negative polyatomic ion
Ammonium + negative polyatomic ion
Polyatomic Ion s

17. How do you name Ternary Ionic Compounds?
EASY! PIECE OF CAKE! NO PROBLEM!
Name the first ion.
Name the second ion. Isn’t that simple??!!
Examples:
When you look at this compound you should recognize that this is NOT binary. There are THREE elements present. When you see this, immediately look for a polyatomic ion. Carbonate is present here.
Na2CO3
Sodium
carbonate
Notice that you do NOT change the suffix – just name the polyatomic ion
Name the first ion.
Name the second ion.

18. A few more examples:
Fe(OH)3
Name the first ion.
Iron
III
hydroxide
Remember that iron requires a Roman Numeral since it is a transition element. What Roman Numeral should be used?
Since there are 3 OH groups, each with a -1 charge, the charge of the iron must be +3 for the compound to be neutral
The Roman Numeral comes from the charge of the ion. How do you find the charge of the iron?
You know two things:
All compounds are neutral.
You know the charge of OH (-1)
Name the polyatomic ion.

19. NH4Cl
Name the first ion.
Ammonium
chloride
Name the second ion.
Notice that since the second ion is a nonmetal that, like binary ionic compounds, the suffix of the nonmetal changes to –ide.
Name the first ion.
(NH4)3PO4
Ammonium
phosphate
Name the second ion.
Looks like a monster, but it’s really a pussycat.

20. ONE more example:
Cu2SO4
Name the first ion.
You should realize that you need a Roman Numeral since copper is a transition metal.
Copper I
sulfate
The Roman Numeral is the same as the charge.
What is the charge?
The charge of sulfate is -2.
Since there are two coppers, the charge of the copper must be +1.
Name the second ion.

21. How do you write formulas for Ternary Ionic Compounds?
Very much like writing formulas for Binary Ionic Compounds.
Two steps:
Write the formulas/symbols of each ion.
Balance the charges by supplying subscripts.
If a subscript is needed for a polyatomic ion, it must be put in parentheses with the subscript on the outside.
Let’s do some!!

22. Al(NO3)3 Aluminum nitrate
First, you can tell from the name that there is a polyatomic ion present (nitrate). All binary ionic compounds have suffixes of –ide.
Al NO3-1
Al(NO3)3
Write the formula/symbol and charge of each ion.
Balance the charges by supplying subscripts.
Since Al is +3 and NO3 is -1, you need a total of 3NO3-1 to balance one Al+3
Since you will need a subscript of 3 for NO3-1, you need to put this in parentheses with the 3 outside.

23. Ca3(PO4)2 Pb(ClO3)4 Lead (IV) chlorate
Write the formula/symbol and charge of each ion.
Pb C2H3O2-1
Balance the charges by supplying subscripts. Since Pb is +4 and C2H3O2 is -1, you will need 4 C2H3O2-1 to balance 1Pb+4
Pb(ClO3)4
Write the formula/symbol and charge of each ion.
Calcium phosphate
Ca PO4-3
Balance the charges by supplying subscripts. Since Ca is +2 and PO4 is -3, you will need 3 Ca+2 to balance 2 PO4-3
Ca3(PO4)2

24. The Third Category of Compounds – Binary Molecular
What are Binary Molecular Compounds?
These compounds contain two elements (binary).
The term “molecular” indicates that these elements are joined by a covalent bond.
They must therefore be nonmetals.
Bottom line – 2 elements – both nonmetals
To name and write formulas for these, you must know some numerical prefixes.

25. Naming – you must use prefixes.
1 = mono 3 = tri = penta = hepta = nona
2 = di 4 = tetra 6 = hexa = octa = deca
Steps
The first nonmetal only gets a numeric prefix when there is more than one. No prefix if there is only one.
The second element always gets a numeric prefix and always has a suffix of -ide

26. Dinitrogen tetraoxide H2O Dihydrogen monoxide CCl4
CO2
Carbon dioxide CO
Carbon monoxide
N2O4
Dinitrogen tetraoxide
H2O
Dihydrogen monoxide
CCl4
Carbon tetrachloride
Name the first element. Since there is only one, no prefix is needed. The second element always gets a prefix and a suffix of –ide.
Name the first element. Since there are two present, the prefix “di” is needed. The second element always gets a prefix and a suffix of –ide.
Do you think it wise to BAN DHMO?

27. AlCl3
What do you think about this one???
Be careful. This is a metal and nonmetal.
Always keep your Periodic Table in front of you for reference.
You may have been tempted to say “aluminum trichloride”. This is INCORRECT!
This is a binary IONIC compound. No prefixes are used. Simply aluminum chloride.
Given the names of binary molecular compounds, how do you write the formulas?
Very easy to do!!! The prefixes tell you how to write the formulas. DO NOT CONSIDER CHARGES. NONMETALS ARE ALL NEGATIVE SO TO USE CHARGES DOES NOT WORK!

28. SiO2 P2Cl5 Silicon dioxide Diphosphorous pentachloride
Silicon and oxygen are both nonmetals.
The lack of a prefix on silicon means that there is only ONE silicon.
The prefix “di” in front of oxide means that there are TWO oxygens.
SiO2
Diphosphorous pentachloride
P2Cl5
Phosphorous and chloride are both nonmetals.
The prefix “di” means that there are TWO phosphorouses (Is that a word?)
The prefix “penta” before chlorine means that there are five chlorines.

29. NO Is this not sooooooo easy!?? Nitrogen monoxide
Nitrogen and oxygen are both nonmetals.
The lack of a prefix on nitrogen means only ONE nitrogen.
The prefix “mono” on oxygen indicates ONE oxygen. NO
Is this not sooooooo easy!??

30. Binary Acids
A simple definition of an “acid” is a substance which produces H+ ions in water.
Most acids have hydrogen ions in their formulas.
A binary acid composed of a hydrogen cation bonded to one other element:
HCl HBr H2S
hydrochloric acid hydrobromic acid hydrosulfuric acid
Binary acids are always named: hydro____ic acid

31. Oxy-Acids
An acid can also be made of a hydrogen ion bonded to a complex ion.
Complex ions whose names end in “ate”:
NO SO42- CO32- PO43-
nitric acid: HNO3
sulfuric acid: H2SO4
carbonic acid: H2CO3
phosphoric acid: H3PO4
Can you propose a rule for naming oxy-acids with complex ions ending in “ate”?

32. More Oxy-Acids Complex ions ending in “ite”: NO2- SO32- ClO- ClO2-
nitrous acid: HNO2
sulfurous acid: H2SO3
hypochlorous acid: HClO
chlorous acid HClO2
Can you propose a rule for naming oxy-acids with complex ions ending in “ite”?