Naming and Writing IONIC Chemical Formulas Chem Lab Methods Naming and Writing IONIC Chemical Formulas

Chemical Symbols

Chemical Formulas: Writing Use the chemical symbol for each element Usually, the element abbreviations come from the word (He for Helium or Ti for Titanium) Some elements have just one letter, such as H for Hydrogen or N for Nitrogen

Chemical Formulas: Writing Most elements have two letters Always capitalize the first letter and use lower case on the second one. Example: Cobalt is Co If you used two capitals (CO), it would be mistaken for Carbon Monoxide which has one Carbon (C) and one Oxygen (O)

Chemical Formulas: Subscripts The subscript number specifies how many atoms of that element you have N2 is a nitrogen molecule with two atoms C2H4 has two carbons and four hydrogens CO2 contains one carbon and two oxygens If no number is listed, it means there is only one

Example C2H3Cl what elements and how many of each?

Example C2H3Cl what elements and how many of each?

Example H2SiCl2 what elements and how many of each?

Example H2SiCl2 what elements and how many of each?

Chemical Formulas: Coefficients (numbers in front) what elements and how many of each?

Chemical Formulas: Coefficients (numbers in front) CH4 => methane what elements and how many of each?

Chemical Formulas: Coefficients (numbers in front) When there are large numbers in front, that tells you how many molecules there are. For example 3CH4 =

Chemical Formulas: Coefficients (numbers in front) When there are large numbers in front, that tells you how many molecules there are. For example 3CH4 = 3 methane molecules 12NaOH = ?

Chemical Formulas: Coefficients (numbers in front) When there are large numbers in front, that tells you how many molecules there are. For example 3CH4 = 3 methane molecules 12NaOH = 12 different Sodium Hydroxide units

Practice Counting Atoms

Definitions Nomenclature: Choosing of names for things Naming procedure Ionic Compound: Atoms held together by ionic bonds Binary Compound: Chemical compound made of atoms from two different elements

Naming: Binary Ionic Compounds Metal element name first Then the non-metal element name, but the ending is changed to -ide Example: CaCl2 would be called calcium chloride Example: Ag2O would be called… silver oxide

Practice Naming Binary Compounds

Ionic Formulas: Developing Example: Compound name - Magnesium chloride …What is the formula?

Ionic Formulas: Developing Magnesium Chloride = What charge ion would each atom form? Mg+2 Cl-1 How many of each to make a neutral compound?

Ionic Formulas: Developing Magnesium Chloride Magnesium= Mg+2 => +2 charge Chlorine = Cl-1 => -1 charge The charges must balance (final compound is neutral) Need TWO Cl-1 ions to balance one Mg+2 ion (2 x -1) = (1 x +2) = 2 each MgCl2

Ionic Formulas: Developing Magnesium Chloride = 1 Mg+2 + 2 Cl-1 => MgCl2 Mg+2 Cl-1

Ionic Formulas: Developing Example: Compound name Lithium sulfide …What is the formula?

Ionic Formulas: Developing Lithium Sulfide= What charge ion would each atom form? Li+1 S-2 How many of each to make a neutral compound?

Ionic Formulas: Developing Lithium Sulfide Lithium= Li+1 Sulfur = S-2 The charges must balance (final compound is neutral) Need TWO Li+1 ions to balance one S-2 ion (2 x +1) = (1 x -2) = two each Li2 S

Ionic Formulas: Developing Lithium sulfide = 2 Li+1 + 1 S-2 => Li2S Li+1 S-2

Ionic Formulas: Developing Example: Compound name Boron oxide …What is the formula?

Ionic Formulas: Developing Boron Oxide= What charge ion would each atom form? B+3 O-2 How many of each to make a neutral compound?

Ionic Formulas: Developing Boron oxide Boron= B+3 Oxygen = O-2 The charges must balance (final compound is neutral) Need SIX cations (B+3) and SIX anions (O-2) (2 x +3) = (3 x -2) = six each B2O3 2 X 3 = 6

Ionic Formulas: Developing Boron Oxide = 2 B+3 + 3 O-2 => B3O2 B+3 O-2

Ionic Formulas: Developing SUMMARY of approach: Determine what charge ion would form from each element Decide how many of each charge are needed to have a balanced (neutral) formula Write formula Subscripts state how many of each ion are needed

Ionic Formulas: KEY POINT Ionic compound formula describes: One “unit” of the chemical compound Thus, it is called a “formula unit” Important definition Example: 3 CaCl2 Three “formula units” of calcium chloride

Practice Writing (Balanced) Chemical Formulas

Ionic Formulas: Continued…. Two more details: Complex ions: contain more than one element Transition metals: ionic charges can vary

Ionic Formulas: Complex Ions Examples: Acetate is (C2H3O2)-1 Whole group has -1 ionic charge Carbonate is (CO3 )-2 Whole group has -2 ionic charge The ENTIRE group has one ionic charge Acts like a single-atom ion of the same charge List of common complex ions on the back of your periodic table

Ionic Formulas: Complex Ions All but ONE of the common complex ions are negative Phosphate is (PO3)-3 Whole group has -3 ionic charge Chlorate is (ClO3 )-1 Whole group has -1 ionic charge THE positive complex ion (worth memorizing) is: Ammonium (NH4)+1

Ionic Formulas: Complex Ions Magnesium Carbonate Magnesium= Mg+2 Carbonate = (CO3)-2 The charges must balance (final compound is neutral) Mg (CO3)

Ionic Formulas: Complex Ions Magnesium Phosphate Magnesium= Mg+2 Phosphate = (PO4)-3 The charges must balance (final compound is neutral) Need SIX cations (Mg+2) and SIX anions (PO4 -3) (3 x +2) = (2 x -3) = six each Mg3 (PO4)2 2 X 3 = 6

Ionic Formulas: Transition Metals Ionic charge can vary How do you know? Listed on Periodic Table “Clue” in name

Examples of naming for metals with multiple charges Element Cation Name Pronounced Copper Cu+ Cu2+ Iron Fe2+ Fe3+ Lead Pb2+ Pb4+ Tin Sn2+ Sn4+

Examples of naming for metals with multiple charges Element Cation Name Pronounced Copper Cu+ Copper (I) copper one Cu2+ Iron Fe2+ Fe3+ Lead Pb2+ Pb4+ Tin Sn2+ Sn4+

Examples of naming for metals with multiple charges Element Cation Name Pronounced Copper Cu+ Copper (I) copper one Cu2+ Copper (II) copper two Iron Fe2+ Fe3+ Lead Pb2+ Pb4+ Tin Sn2+ Sn4+

Examples of naming for metals with multiple charges Element Cation Name Pronounced Copper Cu+ Copper (I) copper one Cu2+ Copper (II) copper two Iron Fe2+ Iron (II) iron two Fe3+ Iron (III) iron three Lead Pb2+ Pb4+ Tin Sn2+ Sn4+

Examples of naming for metals with multiple charges Element Cation Name Pronounced Copper Cu+ Copper (I) copper one Cu2+ Copper (II) copper two Iron Fe2+ Iron (II) iron two Fe3+ Iron (III) iron three Lead Pb2+ Lead (II) lead two Pb4+ Lead (IV) lead four Tin Sn2+ Tin (II) tin two Sn4+ Tin (IV) tin four

Ionic Formulas: Transition Metal Example Write the chemical formula for Iron (II) Oxide Step One: Determine the charges Iron (II) = Fe2+ and Oxide = O2- Step Two: See how to balance the charges Step Three: Find the combination that balances Iron (II) Oxide = FeO

Ionic Formulas: Transition Metal Example Write the chemical formula for Lead (II) Nitride Step One: Determine the charges Lead (II) = Pb+2 and Nitride = N-3 Step Two: See how to balance the charges Step Three: Find the combination that balances Lead (II) Nitride = Pb3 N2

How do you know if you use Roman numerals? Do not use Roman Numerals for groups 1 or 2 as they are always (+1) and (+2) accordingly. K = +1 and Ca = +2 +1 +2

How do you know if you use Roman numerals? Do not use Roman numerals for transition metals that always form the same charge ion. Ag = +1 and Zn = +2 and Cd = +2

Practice Ionic Compound Formula Writing (all types)