4 The periodic table (Lecture) - Copy

Unit Overview

• Chapter Breakdown:

  • States of Matter (03)

  • Elements, Compounds and Mixtures (14)

  • Atomic Structure (24)

  • The Periodic Table (30)

  • Chemical Formulae, Equations and Calculation Part 1 (38)

  • Chemical Formulae, Equations and Calculation Part 2 (64)

  • Ionic Bonding (75)

  • Covalent Bonding (85)

  • Metallic Bonding (98)

  • Electrolysis (101)

Chapter 4: The Periodic Table

• Structure:

  • S Block, P Block, D Block, F Block: Organization of elements based on electron configuration.

• Element Details:

  • Atomic Number: Number of protons in the nucleus.

  • Element Symbol: Abbreviation of the element name.

  • Atomic Mass: Mass of the element (g/mol).

Groups and Periods

• Vertical Columns (Groups):

  • Group 1: Alkali Metals

  • Group 2: Alkaline Earth Metals

  • Group 7: Halogens

  • Group 0: Noble Gases

• Horizontal Rows (Periods):

  • 7 distinct rows representing electron shell filling.

Electronic Configuration

• Valence Electrons:

  • Found in the outermost electron shell.

  • Influences reactivity and bonding pattern.

• Valency:

  • Number of electrons lost or gained to achieve stable configuration.

  • Valency = Valence Electrons for Main Group Elements.

  • Two main cases:

    • If valence electrons ≤ 4, valency equals the number of valence electrons.

    • If valence electrons > 4, valency equals 8 - valence electrons.

Trends in the Periodic Table

• Reactivity Trends:

  • Group 1 (Alkali Metals): Reacts vigorously with water; reactivity increases down the group.

    • Example: Na + H2O → NaOH + H2

  • Group 7 (Halogens): Reactivity decreases down the group.

    • Example: Cl reacts with H to form HCl.

• Noble Gases:

  • Non-reactive due to complete outer electron shells.

  • Exist as monatomic gases (e.g., He, Ne).

Metals vs Non-metals

• Classification:

  • Left of the bold line: Metals

  • Right of the bold line: Non-metals

  • Along the bold line: Metalloids

Properties of Alkali Metals

• Physical Properties:

  • Soft, low density, low melting points.

• **Chemical Properties: **

  • Highly reactive with water and halogens.

  • Compound formation results in characteristic colors in flame tests.

Reactivity Explanation:

• Increasing down Group I

• More electron shells make valence electrons further from nucleus, easier to lose.

Conclusion

• Application for exam preparation: Understand the trends, classifications, and specific reactions associated with groups and periods in the periodic table to predict chemical behavior.