F Centres and the Yellow Colour of NaCl - Colour Hint

The video explains the process of heating sodium in sodium vapor, leading to the deposition of sodium atoms. This causes chloride ions to escape, creating anion vacancies. Electrons then occupy these vacancies, forming F centers, which result in the yellow coloration of sodium chloride crystals. Additionally, the video discusses how excess lithium and potassium can cause pink and violet coloration in crystals, respectively, as examples of metal excess defects.

What happens to chloride ions when sodium chloride is heated?

• They form a new compound.

• They escape to the surface.

• They combine with sodium ions.

• They remain in place.

What is formed when sodium atoms break up?

• Electrons and chloride ions

• Sodium ions and electrons

• Chloride ions and electrons

• Sodium ions and chloride ions

What is the role of electrons in F centers?

• They create anion vacancies.

• They emit yellow light.

• They form sodium chloride.

• They absorb sodium ions.

Which color does excess lithium impart to the crystal?

• Yellow

• Pink

• Blue

• Violet

What is an example of a metal excess defect?

• F center

• Cation vacancy

• Interstitial defect

• Anion vacancy