Ionic Compounds

Predicting Ionic Charges Group 1: Lose 1 electron to form 1+ ions H+ Li+ Na+ K+

Predicting Ionic Charges Group 2: Loses 2 electrons to form 2+ ions Be2+ Mg2+ Ca2+ Sr2+ Ba2+

Predicting Ionic Charges Group 13: Loses 3 electrons to form 3+ ions B3+ Al3+ Ga3+

Predicting Ionic Charges Group 14: Neither! Group 13 elements rarely form ions. Lose 4 electrons or gain 4 electrons?

Predicting Ionic Charges Nitride Group 15: Gains 3 electrons to form 3- ions Phosphide P3- As3- Arsenide

Predicting Ionic Charges Oxide Group 16: Gains 2 electrons to form 2- ions S2- Sulfide Se2- Selenide

Predicting Ionic Charges Group 17: Gains 1 electron to form 1- ions F1- Fluoride Cl1- Chloride Br1- Bromide I1- Iodide

Predicting Ionic Charges Group 18: Stable Noble gases do not form ions!

Predicting Ionic Charges Groups 3 - 12: Many transition elements have more than one possible oxidation state. Iron(II) = Fe2+ Iron(III) = Fe3+

Predicting Ionic Charges Groups 3 - 12: Some transition elements have only one possible oxidation state. Zinc = Zn2+ Silver = Ag+

Making Ionic compounds from elements Remember Metals tend to lose electrons Non-metals tend to gain electrons When a metal, such as sodium, reacts with a non- metal, such as chlorine, both processes occur

Making Sodium Chloride https://www.youtube.com/watch?v=ji_25I_q4LQ

How elements combine https://www.youtube.com/watch?v=4UydtSaZKk4

Ionic Compounds Positive and negative ions from different elements attract each other to form compounds called ionic compounds For example, sodium chloride (table salt) is an ionic compound made up of sodium ions, Na+, and chloride ions, Cl-

Ionic Compounds Ionic compounds that contain only two elements will always have one metal and one non-metal The attraction that holds the charged ions together is called an ionic bond

Ionic Compounds The element aluminum can also react with chlorine gas. Each aluminum atom has three electrons to lose Each chlorine atom can accommodate only one extra electron How can these two elements bond to form a compound?

Ionic Compounds Each aluminum atom reacts with three chlorine atoms to form aluminum chloride, a common ingredient in antiperspirants

Properties of Ionic Compounds Because of the strength of the bond, ionic compounds are hard, brittle solids They have a high melting point Most ionic compounds are also electrolytes This means they dissolve in water to produce a solution that conducts electricity

Naming Ionic Compounds The names of ionic compounds have two parts The first part is the metal ion and the second part is the non-metal ion Remember: The name of the metal ion stays the same The ending of the second ion changes to “ide”

Lets Practice Give the name of the ion for each of the following non-metal elements Chlorine Bromine N-3 Chloride Bromide Nitride Oxygen I- P-3 Oxide Iodide Phosphide Fluorine S-2 Fluoride Sulfide

Writing Chemical Formulas of Ionic Compounds When elements form ionic compounds, elements move from metal atoms to non-metal atoms. The resulting charged ions attract other ions of the opposite charge until the charges balance out. The compound that forms is electrically neutral In other words, the total number of positive charges must equal the total negative charges

Sample Problem 1 What is the chemical formula for magnesium chloride? Step 1 Write the symbols of the elements, with the metal on the left and the non-metal on the right Metal Mg Non-Metal Cl

Sample Problem 1 What is the chemical formula for magnesium chloride? Step 2 Add the ionic charge of each ion above the symbol Metal Mg Non-Metal Cl +2 -1

Sample Problem 1 What is the chemical formula for magnesium chloride? Step 3 Determine how many ions of each type are required to bring the total charge to zero. Metal Mg Non-Metal Cl 1 (+2) 2 (-1)

Sample Problem 1 What is the chemical formula for magnesium chloride? Step 4 Write the chemical formula using the (red) numbers in front of the bracket as subscripts Mg1CL2

Sample Problem 1 What is the chemical formula for magnesium chloride? Step 5 Do not write the subscript “1” in chemical formulas because the symbol itself represents one ion The chemical formula for magnesium chloride is MgCL2

Sample Problem 2 What is the chemical formula for aluminum oxide? Step 1 Write the symbols of the elements, with the metal on the left and the non-metal on the right Metal Al Non-Metal O

Sample Problem 2 What is the chemical formula for aluminum oxide? Step 2 Add the ionic charge of each ion above the symbol Metal Al Non-Metal O +3 -2

Sample Problem 2 What is the chemical formula for aluminum oxide? Step 3 Determine how many ions of each type are required to bring the total charge to zero. Metal Al Non-Metal O 2 (+3) 3 (-2)

Sample Problem 2 What is the chemical formula for aluminum oxide? Step 4 Write the chemical formula using the (red) numbers in front of the bracket as subscripts Al2O3

Sample Problem 3 - Crisscross What is the chemical formula for magnesium chloride? Step 1 Write the symbols of the elements, with the metal on the left and the non-metal on the right Metal Mg Non-Metal Cl

Sample Problem 3 - Crisscross What is the chemical formula for aluminum oxide? Step 2 Add the ionic charge of each ion above the symbol Metal Mg Non-Metal Cl +2 -1

Sample Problem 3 - Crisscross What is the chemical formula for aluminum oxide? Step 3 Crisscross the numbers of the ionic charges so they now become subscripts Metal Mg1 Non-Metal Cl2 +2 -1

Sample Problem 3 - Crisscross What is the chemical formula for aluminum oxide? Step 4 The chemical formula for magnesium chloride is Always write the chemical formula in the simplest terms Al3N3 = AlN MgCl2

Lets Practice Write the chemical formulas for the following ionic compounds Sodium fluoride NaF Magnesium oxide MgO Magnesium chloride MgCl2 Calcium iodide CaI2

Lets Practice Write the chemical formulas for the following ionic compounds Magnesium Nitride Mg3N2 Aluminum Chloride AlCl3 Aluminum Oxide Al2O3 Aluminum Nitride AlN

Elements with Multiple Ionic Charges On the periodic table, you may have noticed that some elements have more than one ionic charge listed. How do we determine which ionic charge is used in a formula? We use roman numerals in the formula to determine the correct ionic charge For example Fe2+ is called iron(II) ion, and Fe3+ is called iron(III) ion The process for naming ionic compounds with multiple charges is similar to the standard method

Sample Problem 4 Write the name of CuBr2. Note that copper could have with an ionic charge of +1 or +2 Step 1 Using the periodic table find the ionic charge of bromide Bromide = -1

Sample Problem 4 Write the name of CuBr2. Note that copper could have with an ionic charge of +1 or +2 Step 2 Total the known charges Since each bromide ion has a charge of -1 and there are 2 bromide ions, we know that the total charge for the bromide is -2 2(-1)=-2

Sample Problem 4 Write the name of CuBr2. Note that copper could have with an ionic charge of +1 or +2 Step 3 Remember that the charge of all the ions must total zero. Since the bromide ions have a total charge of -2 we know that the copper must have a total charge of +2 ? + -2 = 0 +2 + -2 = 0

Sample Problem 4 Write the name of CuBr2. Note that copper could have with an ionic charge of +1 or +2 Step 4 Write the name of the compound. Remember that Roman numerals are included ONLY if the metal has more than one ionic charge. The name of CuBr2 is copper(II) bromide

Sample Problem 5 Write the name of PbO2. Note that lead could have with an ionic charge of +2 or +4 Step 1 Using the periodic table find the ionic charge of oxide. Oxide = -2

Sample Problem 5 Write the name of PbO2. Note that copper could have with an ionic charge of +2 or +4 Step 2 Total the known charges Since each oxide ion has a charge of -2 and there are 2 oxide ions, we know that the total charge for the bromide is -4 2(-2)=-4

Sample Problem 5 Write the name of PbO2. Note that copper could have with an ionic charge of +2 or +4 Step 3 Remember that the charge of all the ions must total zero. Since the oxide ions have a total charge of -4 we know that the copper must have a total charge of +4 ? + -4 = 0 +4 + -4 = 0

Sample Problem 5 Write the name of PbO2. Note that copper could have with an ionic charge of +2 or +4 Step 4 Write the name of the compound. Remember that Roman numerals are included ONLY if the metal has more than one ionic charge. The name of PbO2 is lead(IV) oxide Whenever you have to write the chemical name of a compound containing a metal, first use the periodic table to check if the metal has more than one ionic charge!