Lecture Notes on Ionic and Molecular Compounds

Introduction

• Materials Needed:
  • Periodic table (with element names)
  • Pencil
  • Practice problems will be done along with chemistry jokes for downtime.

Part 1: Ionic Compounds

Definition of Ionic Compounds

• Composed of ions held by electrostatic attraction.
• Electrostatic forces: attraction between positive and negative charges.
• Charge through electron transfer (example: Lithium Chloride).
  • Lithium (Group 1, 1 valence electron) loses electron.
  • Chlorine (needs 1 electron) gains electron.
  • Forms ions: Lithium becomes positive, Chlorine becomes negative.
  • Crystal lattice structure: high melting point, hard, brittle.

Nomenclature Rules for Ionic Compounds

• Cation (Positive Ion):
  • Keep the element name.
  • Mnemonics to remember:
    • "Plussy cat" or "T in cat ion = T in positive"
• Anion (Negative Ion):
  • Add "ide" suffix to element name.
  • Example: Lithium Chloride (LiCl).

Practice Examples

• Sodium Chloride (NaCl): Sodium is cation, Chloride from Chlorine.
• Aluminum Selenide (Al2Se3): Aluminum remains, Selenium becomes Selenide.
• Others: Calcium Bromide (CaBr4), Barium Iodide (BaI2).

Periodic Table and Charges

Common Ionic Charges

• Group 1: +1 charge (Hydrogen exception).
• Group 2: +2 charge.
• Transition Metals:
  • Variable charges, special cases: Silver (+1), Zinc/Cadmium (+2).
• Right of Transition Metals:
  • Boron-Aluminum: Aluminum (+3).
  • Non-metals: Covalent compounds.
  • Nitrogen/Phosphorus: -3 charge.
  • Oxygen Group: -2 charge.
  • Halogens: -1 charge.
  • Noble Gases: Stable, no ionic compounds.

Naming Transition Metals with Roman Numerals

• Example: FeCl3 (Iron III Chloride) - Roman numeral denotes charge.

Polyatomic Ions

• Definition: Covalently bonded elements acting as anions.
• Keep polyatomic ion names unchanged in compounds.
• Naming Patterns:
  • "ite" is one less oxygen than "ate."
  • Halogens: hypo- (less) and per- (more) prefixes.

Part 2: Molecular Compounds and Acids

Molecular Compounds

• Definition: Covalent bonds (sharing electrons), between nonmetals/metalloids.
• Naming Rules:
  • Use prefixes (mono-, di-, tri-, etc.) to denote number of atoms.
  • "ide" suffix on second element.
  • Drop vowel in prefix if a/o before element name.

Practice

• Examples: Carbon Dioxide (CO2), Dinitrogen Pentoxide (N2O5), Sulfur Hexafluoride (SF6), Tetraphosphorus Heptasulfide (P4S7).

Acids

• Definition: Bronsted-Lowry acids donate protons (H+).
• Naming Acids:
  • Anion basis: "ide" to "ic" (add hydro-), "ate" to "ic," "ite" to "ous."

Practice

• Examples: Hydrofluoric Acid (HF), Phosphoric Acid (H3PO4), Hypochlorous Acid (HClO), Perbromic Acid (HBrO4).

Study Tips

• Practice regularly, use periodic table.
• Focus on challenging areas.
• Know common element names and their symbols.
• No need to memorize all charges, focus on common and transition metal exceptions.

Discussion & Questions

• Functional groups not needed for AP Chemistry.
• Continuous practice and understanding rules are key.