Exploring Chemical Compounds Year 9

Exploring Chemical Compounds Year 9

Understanding compounds and their properties Reading and interpreting chemical formulas Classifying and naming compounds

What Are Chemical Compounds?

Two or more different atoms chemically bonded together Have completely different properties from their individual elements Examples: Water (H₂O), Salt (NaCl), Carbon dioxide (CO₂) Cannot be separated by physical means

Compound vs Element Challenge

Sort these substances into elements or compounds: Oxygen (O₂) Water (H₂O) Gold (Au) Carbon dioxide (CO₂) Iron (Fe) Table salt (NaCl)

Ionic vs Covalent Compounds

{"left":"Metal + Non-metal\nElectrons transferred\nForm crystals\nExamples: NaCl, MgO","right":"Non-metal + Non-metal\nElectrons shared\nForm molecules\nExamples: H₂O, CO₂"}

Reading Chemical Formulas

Formula Detective Work

Count the atoms in these formulas: H₂SO₄ (sulfuric acid) CaCl₂ (calcium chloride) C₆H₁₂O₆ (glucose) NH₄NO₃ (ammonium nitrate)

Naming Chemical Compounds

Ionic compounds: Metal name + Non-metal name ending in '-ide' Example: NaCl = Sodium chloride Covalent compounds: Use prefixes (mono-, di-, tri-, tetra-) Example: CO₂ = Carbon dioxide Special cases: Some compounds have common names (H₂O = water)

Think-Pair-Share

Why do you think compounds have different properties from their elements? Discuss with your partner: What happens to electrons when atoms bond? How might this change the behavior of the substance?

Compound Classification Challenge

Classify each compound as ionic or covalent: MgO (magnesium oxide) H₂S (hydrogen sulfide) KBr (potassium bromide) N₂O₄ (dinitrogen tetroxide) Al₂O₃ (aluminum oxide)

Success Criteria & Self-Assessment

✓ I can define what a chemical compound is ✓ I can explain how compound properties differ from elements ✓ I can read and interpret chemical formulas ✓ I can classify compounds as ionic or covalent ✓ I can name simple compounds using systematic rules