Chemical Formula
Kr
Background
With the aim of discovering the missing noble gases in the periodic table, Morris M. Travers and Sir William Ramsay studied liquefied air in 1898. Though the air was already known to contain 99.5% of oxygen, argon and nitrogen, it was difficult to identify the remaining 0.05%.
To identify the unknown part, the chemists first extracted a large volume of argon followed by nitrogen and oxygen using magnesium and red-hot copper. The remaining gas was placed in a vacuum tube to which a high voltage was applied for measuring the gas spectrum. As expected, they found argon gas in addition to two new lines in the spectrum, which was found to be a new element - krypton.
Basic Information
| Name |
Krypton |
| Symbol |
Kr |
| Atomic number |
36 |
| Atomic weight |
83.79 amu |
| Standard state |
Gas at 298 K |
| CAS Registry ID |
7439-90-9 |
| Group in periodic table |
18 |
| Group name |
Noble gas |
| Period in periodic table |
4 |
| Block in periodic table |
p-block |
| Color |
Colorless |
| Classification |
Non-metallic |
| Melting point |
115.79 K (-157.36°C or -251.25°F) |
| Boiling point |
119.93 K (-153.22°C or -243.8°F) |
| Density |
0.0037 g/cm3 |
| Phase at room temperature |
Gas |
Occurrence
Traces of krypton of around 1 ppm are present in the atmosphere. Very small amount of krypton can also be formed in the Earth’s crust when uranium or other radioactive elements disintegrate.
Krypton - Periodic Table of Videos
Isotopes
Krypton has 33 known isotopes with mass numbers ranging from 69 to 101. Of these, six isotopes 78Kr, 80Kr, 82Kr, 83Kr, 84Kr and 86Kr occur naturally. The most abundant isotope in nature is 84Kr (57%) followed by 86Kr (17.3%), 82Kr (11.6%), 82Kr (11.5%), 80Kr (2.3%) and 78Kr (0.4%).
Production
Krypton can be extracted by subjecting liquefied air to fractional distillation and removing carbon dioxide, nitrogen, water vapor and oxygen from the resulting residues of liquefied air.
Key Properties
The key properties of krypton are listed below:
- It is a colorless, odorless, tasteless inert gas
- Solid krypton is white and crystalline
- It can react with fluoride.
Applications
Some of the applications of krypton include the following:
- High-power, flashing airport runway lights
- Krypton-based bulbs serve as excellent white light source for photographic flashes in high speed photography
- It is used for manufacturing colorful neon lights.
- It is used in MRI/CT techniques.
References
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