Alkali Metals: Group 1 Elements

Overview

• Group 1 Elements: Known as alkali metals.
• Elements: Lithium, Sodium, Potassium, Rubidium, Cesium, and Francium.
• Properties:
  • Soft
  • Low densities
  • Low melting points
  • Highly reactive

Reactivity

• React vigorously with water, oxygen, and group 7 elements (e.g., chlorine).
• Reactivity increases down the group:
  • Cesium: So reactive it can ignite spontaneously at room temperature.
• Melting and Boiling Points: Decrease down the group.

Electron Configuration and Reactivity

• Outer Shell: One electron, easy to lose.
• Ionic Formation: Losing one electron forms a positive ion.
• Reactivity Trend:
  • Atomic radius increases down the group.
  • Outermost electron further from nucleus, easier to lose.
  • Reactivity is about electron loss/gain ease.

Ionic Compounds

• Alkali metals form ionic compounds with non-metals.
• Example: Sodium loses an electron to Chlorine forming Sodium Chloride (table salt).
• Properties of Ionic Compounds:
  • White solids
  • Dissolve in water to form colorless solutions

Reactions with Water, Chlorine, and Oxygen

• Water:
  • Produces metal hydroxide and hydrogen gas.
  • E.g., Sodium + Water → Sodium Hydroxide + Hydrogen
  • More reactive metals release more energy and can ignite hydrogen.
• Chlorine:
  • Forms white metal chloride salts.
  • E.g., Sodium + Chlorine → Sodium Chloride
• Oxygen:
  • Forms metal oxides.
  • Lithium: Lithium Oxide (Li₂O)
  • Sodium: Sodium Oxide (Na₂O) or Sodium Peroxide (Na₂O₂)
  • Potassium: Potassium Peroxide (K₂O₂) or Potassium Superoxide (KO₂)

Study Tips

• Use flashcards to remember specific oxide formations.

Conclusion

• Alkali metals have unique properties, trends, and reactions.
• Understanding their reactivity and compound formation is key in chemistry.

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