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S1.1 - Introduction to the particulate nature of matter S1.2 - The nuclear atom S1.3 - Electron configurations S1.4 - Counting particles by mass - The mole S1.5 - Ideal gases S2.1 - The ionic model S2.2 - The covalent model S2.3 - The metallic model S2.4 - From models to materials S3.1 - The periodic table - Classification of elements S3.2 - Functional groups - Classification of organic compounds R1.1 - Measuring enthalpy changes R1.2 - Energy cycles in reactions R1.3 - Energy from fuels R1.4 - Entropy and spontaneity AHL R2.1 - How much? The amount of chemical change R2.2 - How fast? The rate of chemical change R2.3 - How far? The extent of chemical change R3.1 - Proton transfer reactions R3.2 - Electron transfer reactions R3.3 - Electron sharing reactions R3.4 - Electron-pair sharing reactions

S2.3 - The metallic model

2.3.1 Metallic Bonding and Properties of Metal 2.3.2 Strength of Metallic Bonding 2.3.3 Transition Metal (AHL)

Metallic Bonding and Properties of Metals

Specification Reference S2.3.1

Quick Notes:

  • A metallic bond is the electrostatic attraction between a lattice of positive metal cations and a sea of delocalized electrons.
  • This structure gives rise to characteristic metal properties:
    • Electrical conductivity: delocalized electrons move freely and carry charge.
    • Thermal conductivity: energy is transferred by the movement of electrons and vibrations in the lattice.
    • Malleability: metal layers can slide over one another without breaking bonds.
  • Metals are shiny, conductive, and flexible, making them useful in tools, wires, and structural materials.

Full Notes:

What Is a Metallic Bond?

Metallic bonding is the strong electrostatic attraction between positive metal ions (cations) and a sea of delocalised electrons.

Metal atoms form positive ions (cations) easily because their outer electrons are weakly attracted to the nucleus. These electrons can drift away, becoming delocalised and forming a ‘sea’ of negative charge. The resulting positive metal ions are strongly attracted to this sea of delocalised electrons. This electrostatic attraction holds the structure together in a rigid, fixed arrangement.

Example Structure of Sodium (Na)

Each sodium atom loses one outer electron*, forming Na+ ions.

The lost electrons become delocalised, forming an electron cloud.

IB Chemistry diagram of metallic bonding showing a lattice of positive metal ions surrounded by a sea of delocalized electrons.

There is strong attraction between Na+ ions and the delocalised electrons, which holds the metal together.

IB Chemistry schematic for sodium metal showing Na+ ion array and delocalized electron cloud maintaining the metallic bond.

Explaining the Properties of Metals

Metallic bonding helps explain unique physical properties of metals.

Electrical Conductivity

Thermal Conductivity

Malleability and Ductility

Summary of Properties and Bonding

Property How Metallic Bonding Explains It Outcome / Use
Electrical conductivity Delocalized electrons move freely and carry charge through the lattice. Good for wires and electrodes.
Thermal conductivity Electrons and lattice vibrations transfer energy efficiently. Useful in heating elements and heat sinks.
Malleability Layers of ions can slide without breaking the attraction to the electron sea. Can be rolled into sheets for tools and structural parts.
Ductility Non-directional bonding allows stretching into wires without fracture. Drawn into long, thin wires for circuits.
Shiny appearance Surface electrons respond collectively to light (free-electron surface). Characteristic metallic lustre.

Application in Experimental Tools

Metals are used in wires, electrodes, beakers, and support stands due to:

Their bonding and structure make them ideal for frequent handling, high temperatures, and mechanical use in laboratory environments.

Summary