Question

Why is the tungsten used almost exclusively for filament of electric lamps?

Answer 1

Step 1: Reason for using Tungsten in electric bulbs

1. Tungsten, commonly known as wolfram $\left(\mathrm{W}\right)$, is found in Group 6 of the periodic table, placed along with chromium $\left(\mathrm{Cr}\right)$ and molybdenum $\left(\mathrm{Mo}\right)$.
2. The temperature of the electric bulbs is very high. Due to its high melting point and high resistivity at high temperatures, tungsten does not melt very easily. Hence tungsten is used as a heating element for electric bulbs.

Step 2: Properties of Tungsten

1. Tungsten is a strong lithophile element.
2. Tungsten is chemically similar to Molybdenum.
3. Tungsten has two prime oxidation states +4 & +6.
4. Tungsten has a high melting point, high corrosion resistance, high resistivity at high temperature, and lowest thermal expansion properties.
5. Tungsten is a valuable metal that is commonly utilized in light bulb filaments, electron and television tubes, abrasives, and specific alloys like steel.

Hence, tungsten is used as a heating element in electric bulbs due to its high melting point, high corrosion resistance, high resistivity at high temperature, and lowest thermal expansion properties.