Chapter 21, Problem 21.58SP

Interpretation Introduction

Interpretation:

Determine the general unit cell shape for a body-centred cubic structure and draw a unit cell for potassium metal. Explain why you cannot draw an electron-dot diagram for the potassium metal.

Concept introduction:

• There are two theoretical models for bonding in metals which are the electron-sea model and the molecular orbital theory.
• The electron-sea model, when a metal crystal is viewed as a three-dimensional array of metal cations immersed in a sea of delocalized electrons that are free to move throughout the crystal.
• Metals with one valence electron crystallize in a body-centred cubic structure where each central metal atom is surround by 8 neighbouring atoms.

To classify: The unit cell for potassium metal and explain the issue with an electron-dot structure.