Determining Formulas The Criss-Cross Method Examples Na+1 + O-2  Ca+2 + P-3  C+4 + O-2  Na2O Ca3P2 C2O4  reduced to CO2

deduce a chemical formula. Naming Compounds Chemical Nomenclature--> system used to name chemical substances. The Name of a compound indicates the composition of the substance. From the name one can deduce a chemical formula.

Naming Binary Compounds The first element is named as usual but only a stem of the second is used followed by the suffix “ide” For example: MgCl2 is Magnesium chloride : Al2O3 is Aluminum Oxide The Chlorine and Oxygen must change their suffix from “ine” and “ygen” to “ide” !

Naming Compounds Try these! NaCl Li3N MgI2 Sodium Chloride Lithium Nitride Magnesium Iodide

Stock System for Transitional Metals A compound that contains a transitional metal must be named so that the oxidation # of the metal is identified. A Roman numeral is placed after the metal. It represents the oxidation # of the metal. Ex. FeCl3  Iron (III) Chloride CuCl2  Copper (II) Chloride

Assigning Oxidation # Transitional Metals The total charge on any compound or molecule is always equal to zero. To determine unknown oxidation #s, add up the oxidation #s of the Cation and Anion and set them equal to zero. (Create an algebra formula and solve for X.) Example Cr2O3 total charge = 0 Cr = x , O = -2 Formula 2x + 3(-2)= 0  2x-6= 0 x= +3 Cr= +3

Naming Transitional Metal Compound Name These, FeCl2 CrO2 NiP Iron(II) Chloride Chromium(IV) Oxide Nickel(III) Phosphide

Common Names  The old naming system Latin Names Antimony Sb Stibium Copper Cu Cuprum Gold Au Aurum Iron Fe Ferrum Lead Pb Plumbum Mercury Hg Hydragyrum Potassium K Kalium Silver Ag Argentum Sodium Na Natrium Tin Sn Stannum Tungsten W Wolfram

Naming Molecules (Using prefixes) If two non-metals are bonded covalently, the name can be shown using prefixes. The number of atoms for each element in a molecule is usually indicated by the prefix: mono - 1 atom - hexa - 6 atoms di - 2 atoms - hepta - 7 atoms tri - 3 atoms - octa - 8 atoms tetra - 4 atoms penta - 5 atoms

Naming Molecules Examples: nitrogen dioxide is NO2 dinitrogen pentoxide is N2O5 phosphorus tribromide is PBr3 The prefix represents the subscript.  If the subscript is one mono is not needed.

Use Old Naming system and Stock system Binary Molecules Name these ::: Use Old Naming system and Stock system PCl3 PCl5 SO2 Phosphorus TriChloride Phosphorus(III) Chloride Phosphorus PentaChloride Phosphorus(V) Chloride Sulfur Dioxide Sulfer (IV) Oxide

Poly-Compounds Formulas of compounds containing polyatomic ions are written in a manner to stress the fact that the ions are independent units An example is Sodium Nitrate which contains the nitrate ion (NO3)-1 is written NaNO3

Pg 226 lists many more poly-atomic ions Formula Name (NH4)+1 Ammonium (C2H3O2)-1 Acetate (ClO3)-1 Chlorate (CN)-1 Cyanide (OH)-1 Hydroxide (HCO3)-1 Bicarbonate (NO3)-1 Nitrate (CO3)-2 Carbonate (CrO4)-2 Chromate (O2)-2 Peroxide (SO4)-2 Sulfate (PO4)-3 Phosphate Poly-atomic ions Two or more atoms covalently bonded but as a group carry a charge. Pg 226 lists many more poly-atomic ions Memorize ions. all 12

Poly-Compounds When naming these compounds the name of the poly-ion is unchanged. Examples 1. Na2SO4  Sodium Sulfate 2. (NH4)2Se  Ammonium Selenide If Ammonium is the poly-atomic ion, the non-metal still maintains its “ide” suffix.

Poly-Compounds If a compound contains a polyatomic ion with a subscript of two or more the ion is enclosed in parenthesis: Example: calcium bicarbonate Ca(HCO3)2 ammonium sulfide (NH4)2S

Memorize the 12 Common Poly-atomic Ions. Poly-Compounds Name these ::: Go to page 226 or your packet for help. Ca(ClO3)2 NH4OH Cr(SO4)2 Memorize the 12 Common Poly-atomic Ions. There will be an Ion quiz very soon. Calcium Chlorate Ammonium Hydroxide Chromium(IV) Sulfate

Oxy-Ions Polyatomic Ions containing Oxygen can be represented a number of different ways. If one less Oxygen in the formula. The suffix is changed from “ate” to “ite”. The ion’s charge does not change. Ex. (NO3)-1  Nitrate vs. (NO2)-1  Nitrite If two less Oxygens the prefix “hypo-” is placed in front of the “ite” name. Ex. (ClO)-1  hypo- Chlorite If one more Oxygen the prefix “per-” is placed in front of the “ate” name. Ex. (ClO4)-1  Per Chlorate

Acids Acids have their own naming system and they must be recognized when dealing with nomenclature. The name acid comes from the Latin term for “sour” {Acids are sour to the taste} Acids are substances that donate protons (H+) {usually when dissolved in water} The Chemical formula almost always begins with Hydrogen Example: hydrochloric acid  HCl sulfuric acid  H2SO4

Naming Acids Lets separate acids into 2 types: H3PO4 H2SO4 HNO3 H2O Acids that contain oxygen H3PO4 H2SO4 HNO3 H2O Acids that do not contain oxygen HCl HBr HF H2S

Naming Acids For acids containing “-ate” anions: Naming acids containing oxygen: For acids containing “-ate” anions: Use root of the anion (for sulfate, SO42-, use sulfur) Add “-ic” suffix then end with “acid” Example: H3PO4 is Phosphoric acid For acids with “-ite” anions: Use root of the anion (for sulfite, SO32-, use sulfur) Add “-ous” suffix then end with “acid” Example: H2SO3 is sulfurous acid

Naming Acids (cont.) Naming acids not containing oxygen: Add “hydro-” prefix to beginning Use root of the anion (i.e. Cl- use chlor) Add “-ic” suffix then end with “acid” Example: HCl is hydrochloric acid Name the following acids: HF HNO2 HCN H3PO4

Hydrate Molecules A hydrate molecule is a ionic compound that contains water molecules trapped inside the crystalline structure. The Formula includes a dot followed by the number of water molecules Ex: Copper(II) Sulfate Pentahydrate CuSO4 · 5H2O

Hydrate Molecules The Name of a hydrate molecule would include two separate names. To name, use the name of the ionic compound followed by the term … hydrate. A Greek Prefix would be used to represent the number of water molecules that are trapped. CoCl2 · 2 H2O Colbalt(II) Chloride Dihydrate