Lecture on Metallic Properties and Bonding

Overview

• Metals differ significantly from most other elements.
• Key properties of metals:
  • High melting points (mostly, except Group 1 metals)
  • Excellent conductors of electricity and heat
  • High density
  • High tensile strength
  • Ductile (can be made into wires)
  • Malleable (can be shaped into sheets)

Explanation of Metallic Properties

• Metallic Bonding:
  • Metals are formed by atoms losing their last valence electrons.
  • Atoms become cations (positively charged).
  • Electrons become delocalized, forming a "sea of delocalized electrons."
  • Attraction between these free electrons and cations is known as metallic bonding.

Key Properties Explained Through Metallic Bonding

High Melting Points

• Strong forces of attraction (metallic bonds) require a large amount of energy to break.

Conductivity

• Sea of delocalized electrons allows effective conduction of electrical and thermal energy.

High Density and Strength

• Strong attraction among cations and electrons contributes to high density and tensile strength.

Ductility and Malleability

• Layers of cations can slide over each other:
  • Ductility: ability to form wires.
  • Malleability: ability to be hammered into sheets.

Summary

• The unique properties of metals are largely due to the nature of metallic bonding.
• Understanding the behavior of these delocalized electrons and cations explains why metals are strong, conductive, and malleable.