IGCSE Chemistry Study: The Periodic Table (Part 1)

Overview

• Purpose: Learn about the arrangement and structure of the periodic table, focusing on how it helps predict physical properties and chemical reactions.

Arrangement of Elements

• Rows (Periods): Horizontal lines numbered 1 to 7.
  • Indicates the number of electron shells an atom has.
  • Atomic number increases from left to right.
  • Example: Lithium (Atomic number 3, electron configuration 2,1) is in Period 2 because it has two electron shells.
• Columns (Groups): Vertical lines.
  • Indicates the number of electrons in the outer shell.
  • Atomic number increases from top to bottom.
  • Example: Lithium is in Group 1.

Characteristics of Metals and Non-metals

• Metals: Elements that lose electrons to form positive ions.
  • Good conductors of heat/electricity.
  • Shiny, malleable, ductile.
  • High melting/boiling points.
• Non-Metals: Elements that gain/share electrons to form negative ions/covalent bonds.
  • Poor conductors.
  • Dull, brittle.
  • Low melting/boiling points.
• Trend: Across a period, elements transition from metallic to non-metallic.

Group Characteristics and Ion Formation

• Group Number and Electron Configuration:
  • Group 1: 1 electron in outer shell, forms +1 ions (e.g. Na⁺).
  • Group 2: 2 electrons, forms +2 ions (e.g. Ca²⁺).
  • Group 3: 3 electrons, forms +3 ions (e.g. Al³⁺).
  • Group 5: 5 electrons, forms -3 ions (e.g. N³⁻).
  • Group 6: 6 electrons, forms -2 ions (e.g. O²⁻).
  • Group 7: 7 electrons, forms -1 ions (e.g. Cl⁻).
  • Group 0/8: Full outer shell, stable, do not form ions easily.

Chemical Properties and Trends

• Similar Properties in Groups: Elements in the same group react similarly due to similar outer electron configuration.
  • Group 1 elements (e.g. lithium) react with water similarly.
• Periodic Trends:
  • Predict properties like boiling/melting point, density, reactivity based on position in the periodic table.
  • Example: Reactivity increases down Group 1.

Example of Group 1 Reactivity

• Reactivity Trend in Group 1:
  • Lithium reacts slowly with water.
  • Sodium reacts more vigorously.
  • Potassium is more reactive than both.
  • Further down: Rubidium reacts violently, cesium causes explosions.

Conclusion

• Summary: Understanding the arrangement of elements helps predict and explain their properties and reactions.

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