CHAPTER 9
Chemical Names and Formulas
9.1 Naming Ions
• Monatomic Ions: a single atom with a positive or negative charge
• Cation (rules): listed first
• Anion (rules): ide ending
Ionic Compounds
Naming Writing Formulas
Cu3P2 Chromium (III) oxide Copper (II) phosphide Cr2O3
Transition Metals have a varying
Charge
Ions of Transition Metals
• The charges of the cations of many transition metal ions must be determined from the number of electrons lost.
• You must memorize the transition metals that form variable charges.
• Cu, Fe, Sn, Cr, Mn, Hg, Pb, Co, Au
Ions of Transition Metals
• However, all transition metals do not have variable charges.
• If they can become pseudo stable, they usually have one charge only.
• Zn2+, Cd2+, Ag+
Naming Transition Metals
• When these have a variable charge, the Stock system or common name system is used.
• Variable charges exist for certain transition metals that lose a varying number of electrons.
Stock System
• Transition metals with variable charge.
• Roman numerals identify the charge.
• Cu+ = Copper (I), Cu2+ = Copper (II)
• Pb2+ = Lead (II), Pb4+ = Lead (IV)
• Fe2+ = Iron (II), Fe3+ = Iron (III)
• Au+ = Gold (I), Au3+ = Gold (III)
Common Name System
• Transition metals with variable charge.
• Latin name is used for each version.
(ous or –ic endings)
• Cu+ = Cuprous, Cu2+ = Cupric
• Pb2+ = Plumbous, Pb4+ = Plumbic
• Fe2+ = Ferrous, Fe3+ = Ferric
• Au+ = Aurus, Au3+ = Auric
9.2 Ionic Compounds Naming and Writing Formulas
• Ionic compounds are composed of positive cations and negative anions.
• Electrically neutral, meaning the net charge is “zero.”
• Formed from metal and nonmetal
Binary Ionic Compounds
• Binary compounds are composed of two elements.
• The positive charge of the cation must exactly balance the negative charge of the anion
Naming Binary Ionic Compounds
• ide ending
• Stock System
• Roman numerals used on an
“as needed” basis
4 Big Mistakes in Chapter 9
1. Don't know charges
2. Does it end in...ide, ite, or ate
3. Recognizing metals with variable charges 4. Recognizing polyatomic ions
Nitride
Nitrite
Nitrate
Sulfide
Sulfite
Sulfate
Phosphide
Phosphite
Phosphate
Chloride
Chlorite
Chlorate
Lithium Oxide
Chromium (III) bromide
Mg3P2 Fe2S3
Polyatomic Ions
• Polyatomic ions are tightly bound groups of atoms that behave as a unit and carry a charge.
• ite or –ate means oxygen is involved.
Polyatomic vs. Monoatomic
• Must be named differently!!!!
• Monoatomic anions always end with –ide.
• Polyatomic anions end with ide, ite, or ate.
• Always look for a polyatomic ion when naming compounds.
Compounds with Polyatomic Ions
• Ionic compounds containing three or more different elements
• Parentheses used as needed
Naming Ionic Compounds
• Identify the polyatomic ion or monoatomic ion
• Is there a metal with variable charge?
• What is the charge?
(III)
ide, ite, ate
(II) (IV)
Calcium nitrate
Manganese (II) phosphate
Al2(CO3)3 Pb(SO4)2
Mn2(CO3)3 Co3(PO4)2
Variably Charged metal with a polyatomic ion...
Cuprous sulfite
Cobaltic chromate
SnC2O4 Au(ClO3)3
9.3 Molecular Compounds Naming and Writing Formulas
• Composed of two nonmetallic elements
• Ionic charges not used
• Use table of prefixes
• ide ending
Nonmetals
Carbon Silicon Oxygen Chlorine Fluorine Nitrogen
Bromine Iodine Selenium
Boron Sulfur Phosphorus
• C2H4
• S3O6
• H2O
• CO
• CO2
• C2H4 Dicarbon tetrahydride
• S3O6 Trisulfur hexaoxide
• H2O Dihydrogen monoxide
• CO Carbon Monoxide
• CO2 Carbon dioxide
Chemical Naming Rules
• Is there a polyatomic ion?
• Yes…it is ionic.
• No…go to step 2.
• Is it metal to nonmetal?
• Yes…it is ionic.
• No…it is molecular.
Molecular Formula
• A molecular formula shows the number and kinds of atoms present in a molecule
of a compound.
Molecular Compounds
• Tend to have low melting and boiling points
• Exist as gases or liquids at room temperature
• Composed of two or more nonmetals
4 step Naming Process
1. Is there a Polyatomic Ion? (Ionic or Acid) 2. Is there a Metal? (Yes = Ionic)
Fixed or Variable charge
3. Is Hydrogen at beginning? ( If so, its an acid.) 4. If not an Acid or Ionic...
Use prefixes, its molecular
Must Memorize for Ch 9. Test
• 16 Polyatomic Ions
• 9 metals with variable charge
Cr, Mn, Au, Co, Hg, Fe, Cu, Sn, Pb
• 3 Transition Metals with a fixed charge
Zn2+, Ag+, Ni2+, Cd2+
• 10 Prefixes used in molecular compounds
• ous and ic endings
Must Memorize for Ch 9. Test
• 16 Polyatomic Ions
• 10 Prefixes used in molecular compounds
• ous and ic endings
• Acid naming rules
When naming Formulas...
1. Ionic (Metal present)
2. Molecular (Nonmetals only) 3. Acids (Begins with hydrogen)
exceptions: H2O H2O2
9.4 Naming and Writing Formulas for Acids and Bases
•
Acids are a group of compounds that are given special treatment in naming
•
MEMORIZE!!!!
Acids & Bases
Acids: compound containing hydrogen atoms producing H+ when dissolved in water.
Bases: compound producing OH when dissolved in water.
• Rules for Naming Acids
• On page 272
• Rules for Naming Bases
• On page 273
ide ending (HCl, HF, HBr) Monoatomic anion
Hydro (stem) ic
Naming Acids: Rule
#1 HCl:
HF:
HBr:
H
3P:
HCl: Hydrochloric HF: Hydrofluoric HBr: Hydrobromic H3P: Hydorphosphoric
•
Polyatomic anion with ite ending
• (Sulfite, Nitrite, Phosphite)
•
(stem) ous
Naming Acids: Rule
#2
H
2SO
3: HNO
2: H
3PO
3: HClO
2:
H2SO3: Sulfurous Acid HNO2: Nitrous Acid H3PO3: Phoshorous Acid HClO2:Chlorous Acid
• Polyatomic anion with ate ending
• (Sulfate, Nitrate, Phosphate)
• (stem) ic
Naming Acids: Rule
#3
H2SO4:HNO3: H3PO4: HClO3:
H2SO4: Sulfuric acid HNO3: Nitric acid H3PO4: Phosphoric acid
Sulfuric Acid
Hydrochloric Acid
Phosphorous Acid
5 Big Mistakes in Chapter 9
1. Charge mistakes, which lead to formula mistakes 2. Does it end in...ide, ite, or ate
3. Metals with variable and fixed charges 4. Recognizing polyatomic ions
5. Using prefixes incorrectly
Carbonic Acid
Hydrosulfuric Acid
Chlorous Acid
Acetic Acid Rule ___
H2CO3
Rule ___
H2S
Rule ____
HClO2
Rule ___
HC2H3O2
1 compound
9.5 The Laws Governing
Formulas and Names
Law of Definite Proportions:
• In samples of any chemical compound, the masses of the elements are always in the same proportions
Law of Definite Proportions
• 50 grams of H2O.
• 100 grams of H2O.
• No matter how much you have, the ratio of hydrogen to oxygen is always the same.
The Law of Multiple Proportions
• When two elements form more than one compound…
• Different masses of one element combine with the same mass of another element.
• The element with different masses is in the ratio of small whole numbers in their respective compounds.
The Law of Multiple Proportions
• CO: carbon monoxide
• CO2: carbon dioxide
• Even though you have different amounts of oxygen in each compound, the amount of oxygen is still a whole number.
Summary of Naming and Formula Writing
• In an ionic compound, the net ionic charge is zero
4 step Naming Process
1. Is there a Polyatomic Ion? (Ionic or Acid) 2. Is there a Metal? (Yes = Ionic)
Fixed or Variable charge 3. Is Hydrogen at beginning?
If so, its an acid. (Except for H2O & H2O2) 4. All nonmetals, but not and acid.
Use prefixes, its molecular
• An ide ending generally indicates a binary compound
• An ite or ate ending usually means there is a polyatomic anion in the formula.
• Most polyatomic ions contain oxygen!