Chemistry Chapter: Ionic Compounds and Reactions

Ionic Compounds

• Ionic compounds are also known as salts.
• They are typically hard and brittle.
• They conduct electricity when molten or dissolved.
• Ionic compounds have very high melting and boiling points.
• Most ionic compounds are soluble in water.
• They are usually composed of at least one metal and one nonmetal.

Monatomic Ions

• A table lists common simple cations and anions, including their formulas and names.
  • Examples: Hydrogen (H+), lithium (Li+), sodium (Na+), potassium (K+), cesium (Cs+), Beryllium (Be2+), Magnesium (Mg2+), Calcium (Ca2+), Barium (Ba2+), Aluminum (Al3+), and Silver (Ag+).
  • Examples: Hydride (H-), fluoride (F-), chloride (Cl-), bromide (Br-), iodide (I-), oxide (O-), sulfide (S2-).

Predicting Charges on Monatomic Ions

• A periodic table diagram shows the common charges for monatomic ions.
• Metals generally form cations.
• Nonmetals generally form anions.
• The charges of elements are displayed according to their group number on the periodic table
• The general rule for predicting the charge of a metal or a nonmetal is known as the octet rule.

Naming Positive Ions

• To name a positive ion, use the element's name. For most elements, group 1, group 2, aluminum, zinc, cadmium, and silver, the numerical charge isn't shown.
  • Examples: Sodium, magnesium, aluminum, zinc, cadmium, and silver.

Naming Negative Ions

• The ending of negative ions is changed to "-ide".
  • Examples: Oxide, fluoride, chloride, bromide, iodide, nitride, and chloride.

Polyatomic Ions

• A table lists common polyatomic ions, including their formulas and names.
  • Examples: Acetate (C₂H₃O₂⁻), Carbonate (CO₃²⁻), Chlorate (ClO₃⁻), Cyanide (CN⁻), Hydroxide (OH⁻), Nitrate (NO₃⁻), Nitrite (NO₂⁻), Peroxide (O₂²⁻), Phosphate (PO₄³⁻), Sulfate (SO₄²⁻), Sulfite (SO₃²⁻), and Ammonium (NH₄⁺).

Formulas of Ionic Compounds

• The formula of an ionic compound is determined by balancing the charges of the cation(s) and anion(s).
• The numbers are written as subscripts in the ionic compound formula.
• The total positive charge balances the total negative charge.
• Examples:
  • Sodium fluoride (NaF: 1+ and 1-)
  • Aluminum oxide (Al₂O₃: 3+ and 2- )
  • Calcium chloride (CaCl₂: 2+ and 1-).

Writing Formulas for Ionic Compounds

• The formulas for ionic compounds can be written by balancing the charges of the ions.

Balancing Formulas by Math

• Every ionic compound has a total charge of zero.
• Examples: Barium fluoride (BaF₂) and Magnesium oxide (MgO)

Another Way — Drop, Swap, Reduce

• A method to find the formula of an ionic compound, balancing the positive and negative charges:
• "Drop and swap" method means write the number of the positive ion charge as the number of the negative ion and viceversa.
• Reduce to lowest terms
  • Examples: Aluminum oxide (Al₂O₃), Magnesium oxide (MgO), Magnesium hydroxide (Mg(OH)₂), Calcium sulfate (CaSO₄), calcium phosphate (Ca₃(PO₄)₂), ammonium phosphate ((NH₄)₃PO₄) , ammonium chloride (NH₄Cl).

Transition Metals

• Transition metals can have multiple positive charges, thus require numbers in parenthesis to indicate the numerical charge: Roman Numerals
• Transition metal elements are usually found in Groups 3 through 12 of the periodic table.
• Examples: iron (Fe), copper(Cu), cobalt (Co), Manganese (Mn) can have +2 or +3 or even more numerical charge.

Names of Variable Ions

• Elements that need roman numerals to name them, because they can have more than one possible charge.

Transition Metals with Different Charges

• Elements with multiple possible charges (like iron, copper, cobalt, and manganese) require Roman numerals in their names.
• Examples: Iron (II) chloride and Iron (III) chloride
• Examples showing cupric (2+) and cuprous (1+) charges for copper and their formulas.

A Typical Exam Question

• Balancing a chemical equation demonstrating the reaction between iron(II) chloride (or iron (III) chloride) and sodium hydroxide to form iron(II) or iron(III) hydroxide and sodium chloride.

Learning Check

• Questions in tables that show formulas of ionic compounds and to identify the correct formula to specific elements and charges.

Naming Compounds

• To name binary ionic compounds, use the cation first (positive ion), then the anion (negative ion).
  • Give the name of the metal (e.g., calcium).
  • Add "-ide" to the root name of the nonmetal (e.g., chloride).
• Examples showing formulas and names of binary ionic compounds: NaCl, ZnI2, Al2O3, etc

Learning Check

• Compound name questions
• Using appropriate nomenclature rules to identify the naming scheme for the compounds given

Test your knowledge on the formulation and naming of ionic compounds, including reactions involving Iron (III) chloride and sodium hydroxide. This quiz covers the correct chemical formulas and names for various compounds, enhancing your understanding of ionic reactions.