CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

What is the metal excess defect? Explain with examples.


Open in App
Solution

Metal excess defect:

  • It is a type of defect observed in crystals in which excess of metal occurs.
  • There are two types of metal excess defects.

(a) Metal excess defect due to anionic vacancies:

  • This defect occurs in alkyl halides such as NaCl and KCl.
  • In this kind of defect, the negative ion is found to be missing from its lattice site making a hole which gets occupied by an electron to maintain electrical neutrality.

For example:

  • When Sodium chloride (NaCl) crystals are heated in the vapors of Sodium (Na), sodium ions get deposited on the surface on the crystal.
  • Now, Chloride ions (Cl-) move to the surface to get combined with Sodium ions (Na+) to form NaCl.The lattice from where the Chloride ions are displaced now becomes empty which is occupied by the electrons released when Sodium atoms (Na) are converted into Sodium ions (Na+).
  • Thus, as a result, the crystal has an excess of Sodium metal.

(b) Metal excess defect due to the presence of extra cations at interstitial sites:

  • In this defect, extra cations are released on heating the compound.
  • These cations occupy the interstitial sites.

For example:

  • When white Zinc oxide (ZnO) is heated, it loses oxygen and becomes yellow.

ZnheatingZn2++12O2+2e-

  • Now, an excess of Zinc occurs in the crystal and its formula becomes Zn1+xO.

flag
Suggest Corrections
thumbs-up
31
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Metal Excess Defect
CHEMISTRY
Watch in App
Join BYJU'S Learning Program
CrossIcon