Metallic bonding is a core concept in IB Chemistry that helps explain the physical properties of metals—such as conductivity, malleability, ductility, and melting point. This topic appears in atomic structure, bonding, periodicity, and materials science. Understanding metallic bonding clearly will help you answer Paper 1 questions, justify properties in Paper 2, and write strong explanations in your IA.
If you're building your foundation across IB science subjects, Which Science Should I Take in IB? Biology vs Chemistry vs Physics can give you a bigger-picture understanding of how concepts like bonding differ across disciplines.
Quick Start Checklist
Before diving deeper, make sure you know:
- Metallic bonding occurs between metal atoms.
- Electrons become delocalized, forming a “sea of electrons.”
- Positive metal ions are held together by attraction to these electrons.
- The structure is a giant lattice.
- Delocalized electrons explain electrical and thermal conductivity.
These points form the core of any strong exam explanation.
What Is Metallic Bonding?
Metallic bonding is the force of attraction between positive metal ions (cations) and a sea of delocalized electrons. When metal atoms lose their valence electrons, these electrons do not attach to other atoms. Instead, they move freely throughout the metal lattice.
The result is:
- A regular, tightly packed structure
- Free-moving electrons
- Strong electrostatic attraction between the ions and electrons
This bond type is unique to metals and is the reason they have such special properties.
If you want to strengthen your understanding of atomic structure, periodicity, and how bonding fits into the wider IB Chemistry course, IB Chemistry Notes 2025 provides a structured overview.
The Sea of Electrons Model
The delocalized electrons in a metal behave like a “sea” flowing around fixed positive ions. This model explains many metallic properties:
Electrical conductivity
Free electrons move when a voltage is applied, carrying electrical charge through the metal.
Thermal conductivity
Delocalized electrons transfer kinetic energy quickly through the lattice.
Malleability and ductility
Layers of metal ions can slide over each other without breaking the bonding because the electrons move freely and maintain attraction.
Lustre (shiny appearance)
Free electrons can absorb and re-emit photons, giving metals a reflective surface.
Understanding these connections helps you justify real-world properties in Paper 2 questions. If you struggle with long-answer structure, How to Write High-Scoring IB Chemistry Answers provides practical guidance.
Strength of Metallic Bonds
Metallic bond strength depends on:
- Number of delocalized electrons per atom
- Charge on the metal ions
- Radius of the metal ions
For example:
- Magnesium (Mg²⁺) forms stronger bonds than sodium (Na⁺) because it has a higher charge and more delocalized electrons.
- Transition metals often have very strong metallic bonding because they release more electrons into the delocalized sea.
If you want support linking periodic trends with bonding strength, What Are the Key Differences Between IB Chemistry and IB ESS Labs? can help you understand how these concepts are explored experimentally.
Metallic Bonding and Alloys
An alloy is a mixture of metals (or a metal and another element). Alloys modify the metallic lattice to improve properties such as strength and corrosion resistance.
Examples:
- Brass (copper + zinc)
- Steel (iron + carbon)
Alloys usually have distorted lattices, making it harder for layers to slide and increasing strength. This idea often appears in data-based questions comparing materials.
For help planning experiments or discussing materials in an IA, Navigating the IB Chemistry IA provides strong step-by-step guidance.
Frequently Asked Questions
Why can metallic bonds conduct electricity in the solid state?
Because electrons are delocalized and free to move, even in solid metals. This is different from ionic compounds, which conduct only when molten or dissolved.
Why are metals malleable but ionic compounds brittle?
Metal ions can slide without breaking metallic bonds. In ionic lattices, sliding brings like charges together, causing repulsion and shattering.
Why do some metals have higher melting points than others?
Higher charge, smaller ion size, and more delocalized electrons all increase metallic bond strength, raising melting points.
Conclusion
Metallic bonding arises from the attraction between positive metal ions and a sea of delocalized electrons. This structure explains metals’ conductivity, malleability, high melting points, and many industrial applications. A clear understanding of metallic bonding strengthens your explanations across bonding, materials, and periodicity topics in IB Chemistry.
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