Metallic bond

Metallic bond definition

Sharing detached electrons among positive ions with the help of electrons to give the substance a particular shape is called a metallic bond. Since metals have a low ionization energy the valence electrons can be delocalized. These delocalized electrons are free to move and form electron sea. Let us discuss the working and properties of metallic bond.

Metallic bond working

  • Overlapping of the s and p orbitals which are the outer energy levels of metal atoms.
  • None of the valence electrons that take part in the metallic bond are shared with the neighbour atom, nor lost to form an ion.
  • The electrons form a electron sea which helps valence electrons to move from one atom to another atom. This is an oversimplification of metallic bonding process.
  • Calculations based on density functions or electronic band structure are quite accurate.
  • Metallic bonding may result due to more delocalized energy state than delocalized electrons of the material leading to make the localized unpaired electrons mobile and delocalized.
  • The energy state of electrons can be changed as well as their movement throughout a lattice in all directions are allowed.
  • Bonding can also occur in metallic cluster formation where delocalized electrons move around localized cores.
  • Formation of bonds depends on conditions. For example, consider the metal hydrogen under high pressure but as pressure decreases, bond is changed to nonpolar covalent from metallic.

Properties of metallic bond

  1. Thermal conductivity – The free electrons transfer the energy away from the heat source and vibrations of atoms travel as a wave.
  2. Malleability – Metals are capable of being molded into a shape as the bonds between the atoms can readily break and reform. The binding force between metals is nondirectional therefore, the electrons in crystals may be replaceable.
  3. Electrical conductivity – Because the electrons in the electron sea can carry charge and are free to move the metals are brilliant electrical conductors.
  4. Ductility – Metals can be drawn into thin wires as the local bonds between atoms can be easily broken and reformed. Also, thin sheets can be formed.
  5. Metallic lustre – Metals are shiny and display metallic lustre. Once a certain minimum thickness is achieved they become opaque. The attraction between atoms is strong therefore, this makes the metals strong and gives them a high melting point, low volatility, high density, and high boiling point. There are a few exceptions like mercury, etc.

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