Polyatomic Ions

-ate and -ite NO3- nitrate NO2- nitrite -ate is great, -ite is slight -ate has one more oxygen than –ite hypo- under one less per- completely one more

Name other ions by analogy with element above SeO42- selenate BrO3- bromate HSe- hydrogen selenide H2AsO4- dihydrogen arsenate

Permanganate is? MnO2- MgO4- MnO42- MnO4- 130 4

IO- is? hypoiodite iodite iodide iodate iodine monoxide 130 9

Hydrogen selenite is? H2Se H2SeO3 HSeO3- HSeO2- HSeO4- 130 10

Names of Ionic Compounds 1. Name the metal first. For all metals except groups 1,2, Ag, Zn, Al use Roman numerals in parentheses for charge. 2. Then name the polyatomic ion or non-metal, changing the ending of the non-metal to -ide. 3. For hydrates use Greek prefixes to specify the number of water molecules e.g. dihydrate

Some Common Hydrated Ionic Compounds

Simple Salts Ti3N4 titanium(IV) nitride Fe2O3 iron(III) oxide Ag2O silver oxide SnCl4.5H2O tin(IV) chloride pentahydrate Mg3N2 magnesium nitride ZnI2 zinc iodide No roman numerals needed for Ag, Zn, Al Using roman numerals is only wrong for groups 1 and 2

Salts with Polyatomic Ions NH4NO3 ammonium nitrate KBrO3 potassium bromate Mg(MnO4)2.6H2O magnesium permanganate hexahydrate Cu(OH)2 copper(II) hydroxide

Iron(II) phosphate is? Fe2PO4 FePO3 Fe3(PO4)2 Fe2(PO4)3 Fe(PO4)2 130

Zinc iodate is? ZnIO4 ZnIO3 Zn(IO4)2 Zn(IO3)2 ZnI2 10 130

Naming Acids Non-oxy acids hydro___ic acid Oxy acids -ate  __ic acid -ite  __ous acid Always in aqueous solution HCN (aq) hydrocyanic acid H2TeO4 (aq) telluric acid HBrO2 (aq) bromous acid HCN hydrogen cyanide

Hydrosulfuric acid is H2SO4 (aq) H2SO3 (aq) H2OS (aq) HSO4- (aq) H2S (aq) 9 130

Which substance is named correctly? ZnCl2 zinc chloride SCl2 sulfur chloride FeCl2 iron chloride HCl (aq) hydrogen chloride HClO3 (aq) hydrochloric acid 10 130

Properties of Molecular & Ionic Compounds

Electrical Conductivity Ionic Solution

Molar Mass Sum atomic masses represented by formula atomic masses in amu  molecular mass in amu element molar masses in g/mol  compound molar mass in g/mol Numerical values are the same

Percentage Composition Chemical formula gives the relative proportions by atom or mole Percentage composition gives the relative proportions by g (out of 100 g total)

EXAMPLE: What is the percent composition of chloroform, CHCl3, a substance once used as an anesthetic? Molecular mass = (12.011 + 1.008 + 3  35.453)amu = 119.378amu 1(12.011) %C =  100% = 10.061% C 119.378 1(1.00797) %H =  100 = 0.844% H 3(35.453) %Cl =  100 = 89.095% Cl

EXAMPLE: What is the percent composition of chloroform, CHCl3, a substance once used as an anesthetic? %C = 10.061% C %H = 0.844% H %Cl = 89.095% Cl Total = 10.061+ 0.844 + 89.095 = 100.000 

Simplest (Empirical) Formula Simplest integer ratio of the atoms in a compound Assume 100 g of compound, %element is then g element in sample g element x 1 mol element = mol element g element CHCl3 10.061 g C x 1 mol C = 0.83765 mol C 12.011 g C Determine simplest integer mole ratio

EXAMPLE: Phosphorus burns in air to produce a white compound that is 43.7% P and 56.3% O by mass. What is the empirical formula of the compound? Assume 100 g of compound Relative Number of Atoms Multiply by Integer mass 43.7g P 56.3g O (mass/atomic mass) Divide by Smaller 43.7/30.97 = 1.41 56.3/15.9994 = 3.52 2  1.00  2 2  2.50  5 1.41/1.41 = 1.00 3.52/1.41 = 2.50 .25, .33, .5, .67, .75 ¼, ⅓, ½, ⅔, ¾ 1:1.25 = 4:5 Empirical Formula  P2O5

Molecular Formula The exact proportions of the elements that are contained in a molecule An integer multiple (X) of the empirical formula

Molecular Formula from Simplest Formula empirical formula mass  FM sum of the atomic weights represented by the empirical formula molar mass = MM = X  FM

Molecular Formula from Simplest Formula first, knowing MM and FM X = MM/FM then MF = X  EF

EXAMPLE: Our phosphorus compound has a molar mass of ~285 EXAMPLE: Our phosphorus compound has a molar mass of ~285. What is the molecular formula? FM = 2 x 30.97 + 5 x 16.00 = 141.94 MM 285 X = = = 2 FM 141.94 thus MF = 2  EF P4O10

The empirical formula of a substance is found to be CH3O and its molecular weight is found to be roughly 61 g/mol. What is the true molecular weight of the substance? 30.5 g/mol 31.0 g/mol 61.0 g/mol 62.0 g/mol 124.0 g/mol 130 52