Grade 11 Chemistry Name:
Nomenclature Part II
I-Another Method for Naming Metals with TWO valences (Classical System, pg. 103)
Another method of naming binary compounds which have more than one valence or oxidation number is the "IC - OUS" system. This is an older method (classical method) and is less common than the stock system but is still used today.
The "IC - OUS" system uses ous to indicate the lowest valence
and ic to indicate the highest valence
These endings are used on the first element in the compound only. The second element ends in "ide" since it is still a binary compound.
For example : mercury becomes mercuric for +2 valence and
mercurous for +1 valence
There are some elements which use their latin stem names instead of their regular names. (It is actually these latin names that the formula for the element arose from. The latin name was what the elements were known as for centuries.)
i.e. gold - aurum iron - ferrum
Au +1 - aurous Fe +2 - ferrous
+3 - auric +3 - ferric
(Note: the +6 valence has only recently been discovered it
was not known when this naming system was introduced!!)
copper - cuprum lead - plumbum
Cu +1 - cuprous Pb +2 - plumbous
+2 - cupric +4 - plumbic
tin – stannum Mercury
Sn +2 - stannous Hg +1 mercurous
+4 - stannic +2 mercuric
Some other latin names:
- antimony - stibium; mercury - hydrargyrum; potassium - kalium; silver - argentum; sodium – natrium
***This system of naming doesn’t work if the element has more than 2 valences. It should be used in limited circumstances. For example, chromium can form three different ions, and manganese can form five different ions.
Naming Compounds:
Use the same method used for the other types of formulas with the following modifications:
Question: Give the IC - OUS name for SnCl2
1) Names down
2) Check the valences from the Periodic Table:
Sn can be +2 - stannous OR Sn can be +4 - stannic
Reverse criss-cross to find the oxidation number.
Make sure the negative valence is correct. If NOT multiply BOTH valences by the SAME factor)
Name: stannous chloride
Try the following examples:
a) HgO d) AuBr3
b) PbS e) Cu3P
c) SnO2 f) Fe4C3
Writing Formula:
Use the same method criss-cross method as before - the IC/OUS ending tells you which valence to use.
Question: Write the formula for stannic nitride
1) Symbols down
2) Valence down - get the valence for each element from the periodic table
3) Criss-cross
Try these examples:
a) ferrous fluoride c) mercuric carbide
b) plumbous phosphide d) stannous oxide
Worksheet #5:
Fill in the chart below with either the correct name or the correct formula. Use the IC - OUS system of naming.
NAME / FORMULAmercurous oxide
FeO
HgO
ferric oxide
cuprous bromide
CuBr2
stannous fluoride
Sb2S3
SnI4
antimonic carbide
Ferrous chloride
Cu3P2
plumbic sulphide
stannic oxide
PbI2
ferrous nitride
II-Naming Acids
BINARY ACIDS (pg. 384)
Binary gases contain HYDROGEN and a NON-METAL. When these gases are dissolved in water, a binary acid is formed. This process of dissolving does NOT involve a chemical change, so the formula of the acid is the same as the formula of the gas with ONE exception. Binary acids are written with the subscript (aq). This short form represents the word aqueous which means “in solution or water”.
Name of the GAS / Formula / Name of the ACID / Formulahydrogen chloride / HCl / hydrochloric acid / HCl(aq)
hydrogen bromide / HBr / hydrobromic acid / HBr(aq)
hydrogen iodide
HF
hydrogen sulfide
The acid properties are caused by the hydrogen ions (H+) being set free in aqueous solution. The hydrogen ions are said to be hydrated and are commonly called hydronium ions; H+ (H2O) OR H3O+ (preferred representation)
This also helps to explain the prefix HYDRO - it means the gas is HYDRATED - or in water.
OXYACIDS
Oxyacids are acids which contain hydrogen, oxygen and another non-metallic element. We are no longer dealing with just two elements and for this reason the names of the oxyacids DO NOT end in “ide”.
It is the hydrogen which gives the compound its acidic properties. The oxygen and the non-metal are combined in such a way that they remain as a single unit in many chemical reactions. This single unit is called a COMPLEX ION or RADICAL. The valence of the complex ion is equal to the number of hydrogen atoms combined with it in the acid. Complex ions cannot exist by them selves but are found in combination with an electropositive species.
The five main oxyacids are:
Acid Formula / Name of Acid / Complex Ion / Valence / Name of Complex IonHClO3 / chloric acid / ClO3- / -1 / chlorate
HNO3 / nitric acid / NO3- / -1 / nitrate
H2SO4
H2CO3
H3PO4
From these examples it is clear that the ACID ends in “IC” and its complex ion ends in “ATE”.
There are many other forms of the oxyacids. By adding or removing OXYGEN atoms from the above acids and complex ions, new oxyacids and new complex ions are formed.
For example: Look at HClO3 - chloric acid
Acid Formula / Name of Acid / Complex Ion / Valence / Name of Complex IonHClO4 / perchloric acid / ClO4- / -1 / perchlorate
HClO3 / chloric acid / ClO3- / -1 / chlorate
HClO2 / chlorous acid / ClO2- / -1 / chlorite
HClO / hypochlorous acid / ClO- / -1 / hypochlorite
Notice the pattern: Starting from the original acid, OXYGEN is either added or removed resulting in the pattern.
Acid / Complex Ionper...... ic / per...... ate
...... ic / ...... ate
...... ous / ...... ite
hypo...... ous / hypo...... ite
Apply these same rules to the following acids to discover what new oxyacids and complex ions can be formed.
a) HNO3 b) H2SO4 c) H2CO3 d) H3PO4 e) HBrO3 f) HIO3
______
Notes:
1. The formula for persulphuric acid is NOT H2SO5 but is in fact H2S2O8 - WHY? Because it is!!
2. percarbonic, pernitric and perphosphoric acid DO NOT EXIST!!
3. Cl may be replaced by either Br or I to give the corresponding acids and complex ions.
HBrO3 - bromic acid; BrO3- - bromate
HIO3 - iodic acid; IO3- - iodate
4. The (aq) subscript is NOT necessary for these acids because they are not like the binary acids in that they are not just a gas dissolved in water.
5. A special case is acetic acid - CH3COOH; CH3COO- - acetate
This acid is an ORGANIC acid and does not follow the same rules. You should be able to recognize this acid and use the complex ion.
6. You should MEMORIZE the “ic” acid formula and then be able to figure out any other acid by following the pattern.
Name the following acids:
1. HClO 6. HCl(aq)
2. HBrO3 7. HClO4
3. H3PO4 8. HNO2
4. HBr(aq) 9. HNO3
5. HBrO 10. H2CO3
Write the formula for the following acids:
1. sulphurous acid 6. sulphuric acid
2. perbromic acid 7. chlorous acid
3. iodic acid 8. hydrofluoric acid
4. phosphorous acid 9. hypobromous acid
5. carbonic acid 10. acetic acid
III-Naming Bases
In general, the most common bases consist of
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* a metal from group IA,IIA, or IIIA
* combined with the hydroxyl - OH- complex ion.
* when in a compound hydroxyl becomes hydroxide
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For example: NaOH is called sodium hydroxide
Name the following bases:
a) KOH b) Mg(OH)2
c) Zn(OH)2 d) Pb(OH)2
***An exception to this rule is the base which forms with the positive complex ion NH4+ - ammonium.
What would this base be called? NH4OH
Notice how there is NO METAL in this formula. Instead there are TWO complex ions.
Writing Formulas:
Writing formulas for bases follojws all of the rules learned previously including the criss-cross rule.
Every negative complex ion used WILL BE hydroxyl - OH-.
Write the formulas of the following bases:
a) magnesium hydroxide b) cesium hydroxide
c) aluminum hydroxide d) ferric hydroxide
e) lithium hydroxide f) calcium hydroxide
IV-Naming Salts
As you may recall, an ACID is a substance with a HYDROGEN ION, while a BASE is a substance with a HYDROXIDE ION. A SALT is a substance which contains neither. The formation of a salt is the result of:
· A metal or ammonium ion replacing the HYDROGEN in an acid
e.g. Mg + H2SO4 ® MgSO4 + H2
· An acid and base reacting to form a salt and water during a neutralization reaction
e.g. HCl + NaOH ® NaCl + H2O
A - BINARY SALTS
We have already seen many binary salts in the previous nomenclature sections. e.g. NaCl - sodium chloride
Notice there are only two elements in this compound making it a BINARY COMPOUND. Also, notice there is NO HYDROGEN and NO HYDROXIDE making it a salt. Thus NaCl is a binary salt. To name these salts use the methods we have already discussed.
Remember - they will have an IDE ending!!
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KOH + HCl ® KCl + H2O
potassium chloride + water
Fe+2 + H2S ® FeS + H2
ferrous sulphide + hydrogen
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Some exceptions are found: Some compounds are NOT binary compounds (they have more than 2 elements) but are named like binary compounds.
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NH4Br - ammonium bromide
The ammonium radical (NH4+) replaced the H of HBr (hydrobromic acid).
Zn(CN)2 - zinc cyanide
A metal has combined with the complex ion cyanide (CN-)
NaOH - sodium hydroxide
A metal has combined with the complex ion hydroxide (OH-)
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B - SALTS OF THE OXYACIDS (pg. 104)
An oxyacid is an acid which contains oxygen. e.g. HClO3, H2 SO4, H3PO4 etc...
The salt of an oxyacid is formed in the same way that a binary salt is formed.
· A metal or ammonium ion replacing the HYDROGEN in an acid
e.g. Mg + H2SO4 ® MgSO4 + H2
sulphuric acid magnesium sulphate (not magnesium sulphur oxide)
(hydrogen sulphate)
· An acid and base reacting to form a salt and water during a neutralization reaction
e.g. HNO3 + NaOH ® NaNO3 + H2O
nitric acid sodium nitrate (not sodium nitrogen oxide)
(hydrogen nitrate)
• When naming these types of salts, you MUST use the complex ion name for the salt. The radical MUST be treated as if it were a single ion - DO NOT CHANGE THE NEGATIVE ION!!
• You have been given a POLYATOMIC ION sheet which summarizes many of the complex ions you will need to write formulas for this section.
Naming Oxyacid Salts
All of the methods and rules already learned will apply to these compounds. All that is different is the fact the negative valence is no longer a single element - it is a complex ion.
You will have to be able to recognize the complex ions that are in each of the formulas:
e.g. SO4-2 - sulphate, PO4-3 - phosphate, ClO3- chlorate
As well, you will need to remove oxygens from the formula and attach the correct name to each radical produced.
e.g. Start with ClO3- - chlorate
Remove ONE O - ClO2- - chlorite
Remove TWO O - ClO- - hypochlorite
Add ONE O - ClO4- - perchlorate
You are responsible for doing this for ALL complex ions.
For example: Na2SO4
1. Names down: sodium sulphate
2. Check to see if the first element can have MORE than one valence.
If NO, leave the name as it is. In this case - no multi-valence
If Yes, Place the correct Roman numeral in between the two names
3. Check to see if there has been a reduction in the number of atoms.
Try some more:
a) MgCO3 d) KClO3
b) Al2(SO3)3 e) Na3PO4
c) NiCrO4 f) Fe(NO3)3
Writing Formulas of Oxyacid Salts
All of the steps used before are put to use. The criss-cross method still applies. There is one new rule you MUST remember!!
For example: iron (III) carbonate
1. Put down the symbols for the metal and the radical it gives: Fe CO3
2. Put the valence down for each part: Fe+3 CO3 2-
3. Criss-cross the valence over, dropping the signs: Fe 2 CO3 3
4. NEW STEP: Notice how there are now two small numbers on the negative valence. In order for this formula to work you MUST now place BRACKETS around the radical. There will now be a number OUTSIDE the brackets.
Fe 2 (CO3 ) 3
DO NOT CHANGE THE FORMULA OF THE RADICAL BY CHANGING THE SUBSCRIPT. DOING THAT WILL GIVE YOU THE WRONG ANSWER!!!
5. Reduce the formula if possible (Just like in binary compounds)
Try some more - watch the endings:
a) nickel (II) chlorate d) antimony (II) hypophosphite
b) zinc sulphate e) plumbic sulphite
c) aluminum fluoride f) tin (IV) oxalate
V-NOMENCLATURE- SOME EXCEPTIONS
As in most aspects of Chemistry there are some substances that do not follow the rules.
HYDRATES
Many compounds on the storeroom shelf are hydrates. This means the solid has water molecules bonded right into the crystal structure of the molecule. These are dry, crystalline solids. Many of the solid crystals develop colour and interesting crystal shapes when hydrated.
To name hydrates, the Greek prefixes already mentioned are put into use again:
1-mono; 2-di; 3-tri; 4-tetra; 5-penta; 6-hexa; 7-hepta; 8-octa; 9-nona; 10-deca
The name of the hydrate will indicate the number of water molecules in the complex by adding the correct prefix to the ending “hydrate”.