Why is Krypton a Noble Gas? (+ 3 Fascinating Facts to Know)

Krypton is a noble gas because it has a full valence shell of electrons, which makes it stable and unreactive with other elements. Its electronic configuration is characterized by eight valence electrons, which is the stable configuration known as the octet rule. ¹

Well, this was just a simple answer. But there are few more things to know about this topic which will make your concept super clear.

So let’s dive right into it.

Explanation: Why is krypton a noble gas?

Krypton is a noble gas because it has a full valence electron shell, meaning it has a complete outermost energy level of electrons. In the case of krypton, it has a total of 36 electrons, with 8 electrons in the outermost shell. ²

This configuration makes krypton stable and unreactive under normal conditions, which is a characteristic shared by other noble gases such as helium, neon, argon, xenon, and radon. ³

Because noble gases have a full outer electron shell, they do not need to gain or lose electrons to achieve a stable electron configuration.

As a result, noble gases are generally unreactive with other elements and do not form compounds easily. This is why noble gases are often referred to as inert gases.

How is krypton different from other noble gases?

Krypton is similar to other noble gases in that it is chemically inert, has a full valence electron shell, and is monatomic in its elemental form (meaning it exists as single atoms, not molecules). 

However, there are some differences between krypton and other noble gases:

• Atomic number and mass: Krypton has an atomic number of 36 and a mass number of approximately 84, which makes it larger and heavier than the other noble gases, with the exception of radon. ⁴
• Density: Krypton is denser than all of the other noble gases except radon. This density makes it useful in certain applications such as lighting and insulation. ⁵
• Electronegativity: Krypton has a slightly higher electronegativity than the other noble gases, which means it has a slightly stronger attraction to electrons. ⁶
• Spectral lines: Krypton emits a unique set of spectral lines when excited, which makes it useful in certain types of lighting and spectroscopy.

Overall, while krypton shares many characteristics with the other noble gases, its larger size, higher density, and slightly different chemical properties make it distinct from the other members of this group.

Uses of krypton due to its inert nature

Krypton’s inert nature, meaning its lack of reactivity with other elements, makes it useful for a variety of applications. Some of the major uses of krypton due to its inert nature are:

• Lighting: Krypton is used in certain types of high-intensity discharge (HID) lamps, such as those used in automotive headlights and stadium lighting. When an electric current is passed through a krypton-filled bulb, it emits a bright white light.
• Laser technology: Krypton is used as a laser gas in certain types of lasers, such as those used in medical applications and scientific research.
• Insulation: Krypton is used as an insulating gas in some types of windows and other building materials. Because krypton is denser than air, it helps to reduce heat transfer and improve energy efficiency.
• Nuclear medicine: Krypton-81m, a radioactive isotope of krypton, is used in certain medical imaging procedures, such as lung function tests. ^{7 8 9}
• Scientific research: Krypton is used in certain types of research, such as radiometric dating and isotope analysis. ^{10 11 12 13 14}

Overall, krypton’s inert nature makes it useful in a variety of applications where a stable, unreactive gas is needed.

Further reading

Is Krypton a Metal or Nonmetal?
Is Rubidium a Metal?
Is Strontium a Metal or Nonmetal?
Is Silver a Metal or Nonmetal?
Is Hydrogen a Noble Gas?

About author

Jay Rana

Jay is an educator and has helped more than 100,000 students in their studies by providing simple and easy explanations on different science-related topics. He is a founder of Pediabay and is passionate about helping students through his easily digestible explanations.

Read more about our Editorial process.

1. Foundation, C. (n.d.). CK12-Foundation. CK12-Foundation. https://flexbooks.ck12.org/cbook/ck-12-middle-school-physical-science-flexbook-2.0/section/4.12/primary/lesson/noble-gases-ms-ps/
2. P. (n.d.). Krypton | Kr (Element) – PubChem. Krypton | Kr (Element) – PubChem. https://pubchem.ncbi.nlm.nih.gov/element/Krypton
3. Group 18: Properties of Nobel Gases. (2015, May 18). Chemistry LibreTexts. https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Supplemental_Modules_and_Websites_(Inorganic_Chemistry)/Descriptive_Chemistry/Elements_Organized_by_Block/2_p-Block_Elements/Group_18%3A_The_Noble_Gases/1Group_18%3A_Properties_of_Nobel_Gases
4. Krypton – Element information, properties and uses | Periodic Table. (n.d.). Krypton – Element Information, Properties and Uses | Periodic Table. https://www.rsc.org/periodic-table/element/36/krypton
5. P. (n.d.). Density | Periodic Table of Elements. Density | Periodic Table of Elements – PubChem. https://pubchem.ncbi.nlm.nih.gov/periodic-table/density
6. Boudreaux, K. A. (n.d.). The Parts of the Periodic Table. The Parts of the Periodic Table. https://www.angelo.edu/faculty/kboudrea/periodic/trends_electronegativity.htm
7. Watson, I. A., & Waters, S. L. (1986). Pharmaceutical Aspects of Krypton-81m Generators. Progress in Radiopharmacy, 32–45. https://doi.org/10.1007/978-94-009-4297-4_3
8. Lavender, J., Irving, H., & Armstrong, J. (1981, February 1). Krypton-81m ventilation scanning: acute respiratory disease. American Journal of Roentgenology, 136(2), 309–316. https://doi.org/10.2214/ajr.136.2.309
9. Li, D. K., Treves, S., Heyman, S., Kirkpatrick, J. A., Lambrecht, R. M., Ruth, T. J., & Wolf, A. P. (1979, March). Krypton-81m: A Better Radiopharmaceutical for Assessment of Regional Lung Function in Children. Radiology, 130(3), 741–747. https://doi.org/10.1148/130.3.741
10. Krypton-dating technique allows researchers to accurately date ancient Antarctic ice. (n.d.). Krypton-dating Technique Allows Researchers to Accurately Date Ancient Antarctic Ice | NSF – National Science Foundation. https://www.nsf.gov/news/news_summ.jsp?cntn_id=131136
11. Aeschbach-Hertig, W. (2014, April 30). Radiokrypton dating finally takes off. Proceedings of the National Academy of Sciences, 111(19), 6856–6857. https://doi.org/10.1073/pnas.1405830111
12. Scientists successfully use krypton to accurately date ancient Antarctic ice | Argonne National Laboratory. (2014, April 21). Scientists Successfully Use Krypton to Accurately Date Ancient Antarctic Ice | Argonne National Laboratory. https://www.anl.gov/article/scientists-successfully-use-krypton-to-accurately-date-ancient-antarctic-ice
13. NP Radiokrypton Dating Identifie. . . | U.S. DOE Office of Science (SC). (2014, November 25). NP Radiokrypton Dating Identifie. . . | U.S. DOE Office of Science (SC). https://science.osti.gov/np/Highlights/2014/NP-2014-11-a
14. Radiokrypton dating. (n.d.). Radiokrypton Dating. https://atta.ustc.edu.cn/en-us/research/atta.html