Physical Sciences: Compounds and Periodic Table

Introduction

• Presenter: Miss Babo
• Topic: Revision and learning about compounds
• Focus: Periodic table, making and naming compounds

The Periodic Table

• Definition: Table of chemical elements arranged by atomic structure and characteristics
• Structure:
  • Rows: Horizontal
  • Columns: Vertical
• Information in Each Block:
  • Chemical symbol
  • Atomic number (number of protons and electrons)
  • Mass number

How to Use the Periodic Table

• Atomic Number: Equals the number of protons and electrons (for neutral atoms)
• Mass Number: Larger number indicating total number of protons and neutrons

Groups and Periods

• Groups: Vertical columns, same number of valence electrons, similar properties
  • Group 1: Alkali metals
  • Group 2: Alkali earth metals
  • Group 7: Halogens
  • Group 8: Noble gases
• Periods: Horizontal rows, same number of energy levels

Metals, Non-metals, and Metalloids

• Metals: Solid (except mercury), shiny, ductile, malleable, conductors
• Non-metals: Solid, liquid, or gas; brittle, poor conductors
• Metalloids: Solids, semi-conductors

Key Terminology

• Atom: Smallest building block of matter
• Element: Substance made of one type of atom
• Compound: Two or more different atoms chemically bonded
• Diatomic Molecules: Two identical atoms in gaseous phase (e.g., H₂, O₂)

Chemical Bonds

• Metallic Bond: Between metals, "sea of electrons"
• Covalent Bond: Between non-metals, sharing electrons
• Ionic Bond: Between metal and non-metal, transfer of electrons

Naming Compounds

• Steps:
  1. Write the name of each symbol
  2. Identify the bond
  3. Apply naming rules:
     • First element unchanged
     • Second element ends with "-ide"
     • For covalent bonds, add prefixes (mono-, di-, tri-)
• Examples:
  • CO₂: Carbon dioxide
  • NaCl: Sodium chloride
  • SO₃: Sulfur trioxide

Common Names for Compounds

• Water (H₂O): Common name vs. chemical name (hydrogen oxide)
• Other Examples:
  • NH₃: Ammonia
  • HCl: Hydrochloric acid
  • H₂SO₄: Sulfuric acid
  • HNO₃: Nitric acid

Writing Chemical Formulas

• Steps:
  1. Write down symbols
  2. Identify bond type
  3. Determine valencies
  4. Cross over valencies
• Examples:
  • CO₂: Carbon dioxide
  • NaCl: Sodium chloride
  • MgCl₂: Magnesium chloride
  • Li₂O: Lithium oxide

• Conclusion: Understanding of periodic table, chemical bonds, naming, and formula writing
• Next Steps: Further lessons on compounds and reactions

End of Lesson