Chemical Nomenclature Sodium chloride NaCl Carbon dioxide CO2 Copper(II) chloride CuCl2 Chemical Nomenclature Naming compounds and writing the formulas of compounds

3 Sets of Rules of Naming Rules Class or Type I - Ionic Bond between metal predictable + charge and a negative nonmetal or polyatomic ion ; name cations, anion ends in “ide” Examples: NaCl – sodium chloride ; MgCl2, magnesium chloride Class or Type II- Ionic Bond with variable oxidation state transition metal; Roman numerals used to specify charge of transition metal Example: CuCl2 – copper(II) chloride Class or Type III – Covalent bonds between Two nonmetals; uses prefixes Example: CO2 – carbon dioxide; N2O4 – dinitrogen tetroxide

Location of First Element in Formula determines class rules +1 Class or Type I +2 +3 Class or Type II Class or Type III +1 +2

Location of First Element in Formula determines class rules +1 Class or Type I +2 +3 Class or Type II Class or Type III +1 +2

Location of First Element in Formula determines class rules +1 Class or Type I +2 +3 Class or Type II Class or Type III +1 +2

Elements: Sodium = Na and Chlorine = Cl Class or Type I - Ionic Bond between metal with a predictable + charge and a negative nonmetal or polyatomic ion Elements: Sodium = Na and Chlorine = Cl Compound Formula: NaCl Name: sodium chloride Elements: Sodium = Na and Oxygen = O Compound Formula: Na2O Name: sodium oxide Elements: Aluminum = Al and Bromine = Br Compound Formula: AlBr3 Name: aluminum bromide

Class or Type I Compounds Class or Type I - Ionic Bond between metal with a predictable + charge and a negative nonmetal or polyatomic ion Rules for Naming Class or Type I Compounds Name metal cation (positive + ion) first using element name; Name nonmetal anion (negative – ion 2nd); change element name of anion to ends in “ide”  Example #1: NaCl = elements: sodium and chlorine ; Change chlorine → chloride Ans: sodium chloride Example #2: MgCl2 magnesium chloride Link to 2-5 Key

Practice - Name the following compounds: AlCl3 ZnBr2 Ga2O3 aluminum chloride zinc bromide gallium oxide Link to 2-5 Key

Writing Formulas for Class I Compounds Use location on periodic table to find charge for each element Sum of charges must be zero. If + charge ≠ - charge, use “Criss-Cross” technique Final subscripts must be simplest ratio.

Example #1: (+ charge on cation = - charge on anion) What is the formula of potassium bromide? K = group 1 = lose 1 valence e- to fill outer level → +1 ion Br = Group 7 = gain 1 valence e- to fill outer level → -1 ion

What is the formula of potassium bromide? + → [K]+ Charges must balance in final formula. K+1 + Br -1 → KBr

Example #2: (+ charge on cation ≠ - charge on anion) What is the formula of calcium nitride? Ca = group 2 = lose 2 valence e- to fill outer level → +2 ion N = Group 5 = gain 3 valence e- to fill outer level → -3 ion

What is the formula of calcium nitride? Charges: Ca+2 N-3 Criss-Cross move charge # (ignore + or – ) to subscript on opposite ion Ca+2 N-3 Final Answer: Ca3N2

Conceptual basis of “criss-cross” Total + must = total - ; Least common multiple (3) (+2) = +6 2 (-3) = -6 Ca+2 Ca+2 Ca+2 = +6 N-3 N-3 = -6 N -3 N -3 Ca +2 Ca +2 Ca +2

Practice- write formulas for the following compounds Magnesium sulfide Mg+2 S-2 → Aluminum oxide Al+3 O-2 → Potassium sulfide K+1S-2 → MgS (simplest ratio) Al2O3 K2S