Nomenclature Chapter 2

Chemical Formulas Formula Unit: Molecular formula: Empirical formula: Identifies exact number of atoms in an ionic compound Molecular formula: Identifies exact number of atoms in a covalent molecule Empirical formula: Shows the simplest whole number ratio of atoms in a compound H2O molecular empirical C6H12O6 CH2O O3 O N2H4 NH2

7 DIATOMIC ELEMENTS HOFBrINCl Some elements do not like to be alone… so they bond to themselves! 7 HOFBrINCl

The ionic compound NaCl Ionic Compounds consist of a combination of cations and anions formed from a transfer of electrons the formula unit is always identical to the empirical formula the sum of the charges on the cation(s) and anion(s) in each formula unit must equal zero The ionic compound NaCl

NAMING BINARY IONIC COMPOUNDS RULE 1 Metal – Nonmetal Write the metal (positive ion) first Change the ending of the second word to -ide

Rule 1 Examples KBr CaBr2 LiF Li2O MgO BaS K3P Na3N Potassium Bromide Calcium Bromide Lithium Fluoride Lithium Oxide Magnesium Oxide Barium Sulfide Potassium Phosphide Sodium Nitride

NAMING COMPOUNDS WITH POLYATOMICS RULE 2 Polyatomic Ions DO NOT CHANGE ANYTHING! When you have NH4 and a single element, change the second word to -ide

Rule 2 Examples Ba(SO4) Ba(SO3) Na2(CO3) Na(HCO3) (NH4)3(PO4) (NH4)(OH) Barium Sulfate Barium Sulfite Sodium Carbonate Sodium Bicarbonate Ammonium Phosphate Ammonium Hydroxide

Formula of Ionic Compounds 2 x +3 = +6 3 x -2 = -6 Al2O3 Al3+ O2- 1 x +2 = +2 2 x -1 = -2 Ca Br2 Ca2+ Br- 1 x +2 = +2 1 x -2 = -2 Na2CO3 Na+ CO32-

NAMING COMPOUNDS WITH TRANSITION METALS RULE 3 Transition Metals Can have more than one type of charge Write the charge number in roman numerals

Rule 3 Examples Cu2O CuO FeCl2 FeCl3 SnCl4 Mn2O3 PbS Copper (I) Oxide Copper (II) Oxide Iron (II) Chloride Iron (III) Chloride Tin (IV) Chloride Manganese (III) Oxide Lead (II) Sulfide

FeCl3 • 6H2O = Iron (III) Chloride Hexahydrate NAMING HYDRATES What is a hydrate? Hydrates are named: Compound • Prefix-Hydrate FeCl3 • 6H2O = Iron (III) Chloride Hexahydrate

Name to Formula – Criss Cross Rule Lithium Fluoride Sodium Sulfide Aluminum Bromide Iron (III) Oxide Carbonic Acid Calcium Carbonate Magnesium Acetate Copper (II) Sulfate Pentahydrate Ammonium Sulfite Barium Hypochlorite

Covalent Compounds Referred to as molecules Consists of nonmetals covalently bonded nonmetals or nonmetals + metalloids Least electronegative element is usually written first

NAMING COVALENT COMPOUNDS RULE 4 Nonmetal – Nonmetal USE PREFIXES! Change the ending of the second word to -ide No mono on the first word Drop any double vowels TOXIC! NO2 nitrogen dioxide N2O dinitrogen monoxide Laughing Gas

Prefixes Number of Atoms Prefixes 1 2 3 4 5 6 7 8 9 10

Rule 4 Examples CO CO2 SO2 SO3 N2H4 N2O3 PCl3 SiO2 P2O5 CS2 Al2O3 Carbon Monoxide Carbon Dioxide Sulfur Dioxide Sulfur Trioxide Dinitrogen Tetrahydride Dinitrogen Trioxide Phosphorus Trichloride Silicon Dioxide Diphosphorus Pentoxide Carbon Disulfide Aluminum Oxide

ACIDS a substance that yields hydrogen ions (H+) when dissolved in water. example: hydrochloric acid refers to a water solution of the molecular compound hydrogen chloride, HCl Many polyatomic ions are produced by the loss of hydrogen ions from oxyacids. Acid Name: Polyatomic Ion: sulfuric acid H2SO4 sulfate nitric acid HNO3 nitrate phosphoric acid H3PO4 phosphate

NAMING ACIDS Binary acids: consist of two elements, usually hydrogen and a halogen “HX” Oxyacids: contain hydrogen and a polyatomic ion (usually oxygen and a third nonmetallic element) “HXO”

NAMING BASES NaOH sodium hydroxide KOH potassium hydroxide Ba(OH)2 Base: a substance that yields hydroxide ions (OH-) when dissolved in water. NaOH sodium hydroxide KOH potassium hydroxide Ba(OH)2 barium hydroxide