Question

Many metals such as gold or aluminum can be hammered into thin sheets. This property of metals is called malleability. Which of the following statements best explains why metals are malleable when a stress is applied to them?

• A. The atoms move into a new arrangement, but they are still surrounded by a "sea" of mobile valence electrons.
• B. The atoms begin to experience strong repulsive forces between the cations in the crystal structure.
• C. The dipole-dipole forces between the molecules are broken, causing the molecules to spread out and move away from each other.
• D. The atomic radius of the atoms decreases, causing the atoms to move closer towards each other.

Answer 1

Answer: (A)

The atoms move into a new arrangement, but they are still surrounded by a "sea" of mobile valence electrons.

Metals are malleable because the atoms can roll over each other and retain the structure of the crystal due to Metallic Bonding. Metallic bonds involve all of the metal atoms in a piece of metal sharing all of their valence electrons with delocalized bonds. A metal therefore behaves as an array of metal ions immersed in a sea of mobile valence electrons. Whenever a metal receives a stress, the position of adjacent layers of metallic kernels shifts. The deforming force moves atoms into a new arrangement but the environment of the kernel do not change and are moved from one lattice site to another.