3.4 Metallic Bonds

Learning Objectives

  • Define the properties of metallic bonds and delocalised electrons
  • Understand the general characteristics of metals.

To complete our types of bonding, metallic bonds present when metals are bonded to other metals together in a lattice. Metallic bonds exhibit unique sets of properties within compounds, all due to a sea of delocalised electrons (see Figure 3.4.1).

A diagram of metallic bonding, where a dense array of large red spheres labeled with positive signs depicts the metal cations or kernels carrying a positive charge. These cations are embedded in a 'sea' of delocalized valence electrons, shown as small blue spheres with negative signs.
Figure 3.4.1: Diagram of Metallic Bonding. Image attribution: Metallic bonding: The electrostatic attractive force between the delocalised electrons present in the metallic lattice and the positively charged metal atom core. © Reuel Sa – stock.adobe.com.
Copper wires in different coloured plastic coatings on a black background.
Figure 3.4.2: Copper wire is the backbone of a lot of electrical systems, thanks to copper’s low-cost, ductility and ability to be drawn into a conducting wire. Image attribution: Kabel © demarco – stock.adobe.com.

In covalent and ionic bonds, the electron is tied between one or two atoms. Within metallic bonds, valence electrons are essentially liberated from any individual atom due to electron orbitals overlapping, allowing electrons to flow freely within the lattice. These delocalised electrons require significantly less energy to shift around due to a lack of attraction forces to the nucleus. Even with just a small current, electrons will readily move throughout the structure. This makes metals fantastic conductors of electricity and heat!

The metallic lattice that forms and delocalised electrons cause metals to be malleable and ductile. Metals that are subjected to forces are able to shift their atoms whilst retaining the delocalised electrons and the lattice structure.

Metals are generally characterised as having high melting points and being lustrous, paramagnetic, and solid at room temperature; however, the individual electronic configuration of metallic elements does cause exceptions to arise. Mercury, for instance, is a transition metal but is a liquid at room temperature.

A structural chemical diagram of EDTA, ethylenediaminetetraacetic acid, forming a complex with a central metal ion bonded to six different atoms drawn as dashed lines. The molecule is complex in its structure in a somewhat octahedral shape.
Figure 3.4.3: EDTA (Ethylenediaminetetraacetic acid) bonded to a metal ion. Image attribution: an image from the public domain courtesy of Wikimedia Commons.

You may notice we are glossing over metallic bonding! We stress that students are aware of the general characteristics of metals, being delocalised electrons leading to the high conduction of electricity and heat alongside high melting points due to the rigid lattice. You’ll often be using hotplates or other metal implements in the lab, so understanding why they work is important! However, tertiary chemistry studies don’t focus on traditional metallic bonding. The study of inorganic chemistry focuses on the formation of metal complexes through bonding with ‘ligands’ that attract metal ions. Inorganic chemistry requires its own separate field of study, as metals can form many more bonds than would be traditionally expected (see Figure 3.4.3).

Inorganic chemistry often deals with how the oxidation states and coordination of transition metals change with respect to pH, heat and other variables. These oxidation states often produce energy changes with wavelengths within the visible spectrum, making inorganic chemistry one of the more colourful and exciting fields (see Figure 3.4.4)! For now, however, this study is outside the scope of this textbook.


Four small test tubes, each containing purple, green, blue and yellow vanadium solutions.
Figure 3.4.3: Vanadium complexes of different oxidation states. Image attribution: an image from the public domain courtesy of Wikimedia Commons.

Key Takeaways

  • Metallic bonding occurs when metals are bonded in a lattice.
  • Metallic bonds feature a sea of delocalised electrons due to overlapping electron orbitals.
  • Delocalised electrons allow for the easy conduction of heat and electricity compared to other elements and compounds.


Practice questions




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