CHEM 111: 2.6-2.7

Introduction

  • Homework Questions
    • Part of overall homework grade.
    • Focus: Algebra basics required for the course.
    • Due next week alongside material from Chapter 1, Chapter 2, and parts of Chapter 3.

Previous Class Review

  • Section 2.6: Discussion on compounds and their classification.
    • Types of Compounds:
    • Ionic Compounds: Made of metals (left side of the periodic table) and nonmetals (right side).
    • Molecular Compounds: Composed solely of nonmetals.
    • Writing Formulas for Ionic Compounds:
    • Importance of recognizing if a compound is ionic or molecular.
    • Common exam question; frequent student mistakes noted.

Identifying Ionic and Molecular Compounds

  • Ionic Compounds:
    • Contain elements from left and right sides of the periodic table. Example:
    • Sodium (Na), Sulfur (S), Oxygen (O):
      • Sodium is a metal (left); sulfur and oxygen are nonmetals (right) → Ionic compound.
    • Molecular Compounds:
    • Example of molecular compound:
      • NH₃ (Ammonia): Contains hydrogen (considered a nonmetal here) and nitrogen (nonmetal).
      • Example of another molecular compound:
      • SO₂: Both sulfur and oxygen are on the right side of the periodic table.

Think-Pair-Share Activity

  • Exercise:
    • Identify if examples given (e.g., Ba(OH)₂) are ionic or molecular.
    • Answer for Ba(OH)₂: Ionic, due to presence of barium (metal on left).
    • Exception: Polyatomic ions can exist in ionic compounds, like NH₄⁺ (ammonium) which serves as a cation.

Recap of Compounds' Structures

  • Atoms and Molecules:
    • Element vs. Molecule:
    • Atom: Single unit (e.g., carbon, iron).
    • Molecule: Collection of atoms (same element or different elements).
    • Types of Compounds:
    • Molecular Compounds:
      • E.g., H₂O (water), CO₂ (carbon dioxide); consist of various nonmetals.
    • Ionic Compounds:
      • Formed from a lattice of ions, not discrete molecules.

Section 2.7: Chemical Nomenclature

  • Definition: The set of rules for naming chemical compounds.
  • Types of Compounds Nomenclature:
    • Ionic Compounds:
    • Molecular Compounds:
    • Inorganic Acids: Definitions and brief characteristics.

Naming Ionic Compounds

  • Steps to Name:
    • Identify cation (positive ion) and anion (negative ion).
    • Monatomic Cations: Use element name (e.g., Mg²⁺ = Magnesium).
    • Monatomic Anions: Change ending to -ide (e.g., Cl⁻ = Chloride).
    • Polyatomic Ions: Names remain unchanged (e.g., SO₄²⁻ = Sulfate).
    • Transition Metals: Use Roman numerals for charge in compound names (e.g., Fe³⁺ = Iron (III)).

Monatomic Anions Table

  • Common Monatomic Anions and their Names:
    • F⁻ → Fluoride
    • O²⁻ → Oxide
    • S²⁻ → Sulfide
    • N³⁻ → Nitride

Examples of Naming Compounds

  • Ionic Compound Example: NaCl
    • Na⁺ (Sodium) + Cl⁻ (Chloride) = Sodium Chloride.
  • Ionic Compound with Polyatomic Ion Example: Na₂SO₄
    • Sodium (cation) with Sulfate (anion) = Sodium Sulfate.

Naming Molecular Compounds

  • Process for Naming:
    • Name the first element as it appears.
    • Change the second element's ending to -ide.
    • Use prefixes to indicate quantity (mono-, di-, tri-, tetra-, penta-, hexa-).
    • Example: CO₂ = Carbon Dioxide.

Prefixes for Molecular Naming

  • 1: Mono
  • 2: Di
  • 3: Tri
  • 4: Tetra
  • 5: Penta
  • 6: Hexa
  • Note: Mono is omitted for the first element.

Common Mistakes in Naming

  • Spelling Errors:
    • Watch for spelling mistakes in ionic and molecular names.
  • Common Compound Names:
    • Recognize common names such as Ammonia (NH₃) and Water (H₂O).

Brief on Acids

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