Mission B5 - How do you Name and Write chemical formulas for Compounds? “Not Just James Bond”

Part 1 - Naming Binary Compounds Binary compounds – elements with only two types of atoms in it Naming binary compounds is simple It is based on the names of the cations and anions and all binary compounds end in -ide Examples: NaCl = sodium chloride CaF2 = calcium fluoride Al2O3 = aluminum oxide BaO = barium oxide 2

Part 2 - Naming Transition Metal Compounds Similar to naming binary compounds But transition metals have multiple oxidation states (can have different charges) Steps determine the oxidation number of the nonmetal use the rules of oxidation states to solve The name must have Roman numerals to show the oxidation state of the metal 3

Therefore CuCl2 is called copper II chloride Example: CuCl2 Step 1 determine the charge on the chlorine Chlorine has a higher EN therefore will be a negative oxidation state which is -1 But there are two chlorines so the total is -2 Step 2 Determine the charge on the copper The compound’s total charge must equal zero Copper must be a +2 charge to balance the chlorine Therefore CuCl2 is called copper II chloride 4

what is the charge on the chlorine? Example: In FeCl3 Step 1 what is the charge on the chlorine? -1 = it has the higher electronegativity and is negative What is the total charge of 3 chlorines? -3 = 3 x -1 Step 2 what is the charge on FeCl3? Zero = charges in compounds add up to 0 What is the charge on the iron then? +3 = chlorine’s -3 + iron’s +3 = 0 What is the name of the particle FeCl3 then? iron III chloride = “III” shows the iron’s charge 5

Part 3 - Naming Polyatomic Compounds Polyatomic ions Groups of atoms that have a collective charge on them See CRTable E Similar to binary naming If more than two elements in the compound, look up the polyatomic ion on Table E Example [Na]+ + [SO4] 2- Na2SO4 sodium + sulfate = sodium sulfate 6

Naming Polyatomic Compounds Examples Na2CO3 = sodium carbonate HCN = hydrogen cyanide KClO3 = potassium chlorate NH4Cl = ammonium chloride 7

Part 4 - Naming Molecular Compounds Naming molecular compounds (covalently bonded substances) is similar to naming ionic ones with one exception: When naming substances with all nonmetals Prefixes are used to designate the number of atoms of each Prefix # of Atoms Formula example Name mono 1 CO Carbon monoxide di 2 CO2 Carbon dioxide tri 3 SO3 Sulfur trioxide tetra 4 CCl4 Carbon tetrachloride penta 5 PCl5 Phosphorus pentaflouride

Examples of Naming Covalent Compounds CO - carbon monoxide CO2 - carbon dioxide SO2 - sulfur dioxide N2O3 - dinitrogen trioxide SF6 - sulfur hexafluoride H2O - dihydrogen monoxide

When writing chemical formulas Writing Formulas When writing chemical formulas Reverse the rules for writing chemical names Here are examples of each type of chemical formula Ex 1 - Binary compound - sodium chloride sodium’s oxidation number is Na+1 chlorine’s oxidation number is Cl-1 Charges are equal and cancel each other Therefore the chemical formula = NaCl 10

Writing Chemical Formulas Ex 2 - Binary compound - aluminum chloride one aluminum has is Al+3 one chlorine is Cl- It takes one Al+3 to balance the charge of three Cl- Therefore the formula for aluminum chloride is AlCl3 Ex 3 - Transition metals – iron II oxide one iron II has a charge of Fe+2 one oxygen has a charge of O-2 The two charges balance out to a 1:1 ratio Therefore the formula for iron II oxide is FeO 11

Writing Chemical Formulas Ex 4 - Nonmetal-nonmetal compounds - dinitrogen trioxide Oxidation numbers aren’t required in writing this formula Dinitrogen is two nitrogens Trioxide is there oxygens Therefore the formula for dinitrogen trioxide is N2O3 12

Writing Chemical Formulas Ex 5 - Polyatomic ions – magnesium nitrate Magnesium (Mg+2) is in Group 2 and has a +2 oxidation charge Nitrate (NO3-) is a polyatomic ion from Table E with an oxidation number of -1 So two nitrates are needed to balance the one magnesium and give a zero charge Therefore the formula for magnesium nitrate is Mg(NO3)2 13

Writing Chemical Formulas Ex 6 - Polyatomic ions and transition metals – copper I sulfate Copper (Cu+1) has a +1 charge as per the Roman numeral Sulfate (SO4-2) is a polyatomic ion from Table E with an oxidation number of -2 So two coppers are needed to balance the one sulfate and give a zero charge Therefore the formula for copper I sulfate is Cu2 SO4 14

Writing Chemical Formulas A short cut – the Criss-Cross method of writing Look at the oxidation states of the elements in the compound cross the numbers, drop the charges, and you will have the formula Example – lead II chloride Lead +2 charge Chlorine -1 charge Pb +2 Cl -1  Pb1Cl2