The Colorless Element Krypton

picture of krypton

The Element Krypton

Introduction to Krypton

Stationed in the non-metals category of the periodic table sits the colorless element Krypton. It is categorized as a noble gas and can be found in group 18. Not only is the element colorless it also does not contain an odor.

Ten Interesting Facts About Krypton

  • Kr is commonly used as a commercial filling gas for energy-saving fluorescent lights.
  • This noble gas is one of the rarest elements on Earth. It composes only one part per million of the atmosphere by volume.
  • The element krypton was discovered partially by accident, which is why it is named after the Greek word “Krypto” which means “hidden.”
  • Although Kr is rarely present on Earth it is abundant on stars like the sun.
  • Krypton has a half life of 10.76 years. When in an electric field its appearance is a whitish glow.
  • The flash from a camera contains Krypton, because of the bright light source, in the medical field krypton is used to detect abnormal heart openings.
  • Krypton will emit a reddish orange light when it is placed in high pressure low temperature environments. Sir William Ramsey and Morris Travers observed this when they first discovered the element. Since then this color has become significant in signs that are fluorescent like “exit” signs in buildings.
  • One common use of krypton use to be obtaining artificial rubies.
  • Kr discharges a greenish/yellow glow when it is mixed with other gases.
  • This element and the other group 18 elements on the periodic table were among the last elements to be discovered.

Kr on the Periodic Table

Krypton is a chemical element with the symbol Kr. It lies in group 18 and period 4, to the right of bromine and below Argon. It is in the noble gas family and tends not to react with other elements because it already has its desired s and p electrons in their valence energy level. The element has an atomic number of 36, melting point of -157 degrees celsius, and a boiling point of -153 degrees celsius.

Krypton is very similar to the other noble gases because it is colorless, odorless, and is not very chemically reactive. Krypton has an electronegativity of 3.


In 2014 scientists successfully used the krypton-dating technique to identify the age of a 120,000 year old sample of Antarctic ice. Much like the very common carbon-dating technique, krypton-dating measures the decay of a radioactive isotope, that has constant and well known decay rates and compares it to a stable isotope. Since Krypton is a noble gas, it does not interact chemically with other elements and has a half life of about 230,000 years. Carbon dating doesn’t work well on ice because carbon-14 is in the ice by cosmic rays. It has radioactive isotope (Kr-81) which decays slowly, and a stable isotope (Krypton-83) which does not decay. When you compare the proportion of stable-to-radioactive isotopes provides the age of the ice. With this new technique researchers believe that they may be able to date ice back up to 1.5 million years.

Deep Mantle Krypton

Using the different isotopes of Kr scientists are able to create a sort of chemical fingerprint that displays the ingredients that made the Earth. Kr from Earth’s mantle is collected from geologic hotspots, volcanic locales thought to be fed by underlying mantle that is very hot compared to the surrounding mantle. Places like the Galapagos Islands and Iceland reveal a clearer picture of how our planet was created. The findings indicate Earth’s volatile elements arrived as Earth was growing and shaping itself as a planet. This information is important because it contradicts the popular theory that Earth’s volatile elements were mostly delivered near the end of the Earth’s formation. The isotopes suggest that planetesimals, minute planets, from the outer solar system bombarded the Earth early on.


Krypton in Today’s World


Often, Krypton, and xenon, are used in some photographic flashes for high speed photography. The flash tubes in a camera are made up of electrodes that are filled with gas in both ends that, when triggered, ionizes and produces a high voltage pulse to produce light. Xenon flash tubes emit light in various spectral lines. Krypton is another substance used in flash tubes. It can be as good as 40% efficient, but it needs at least a 70% increase in pressure over xenon to achieve a more efficient flash.

Medical Diagnosis

While Kr is quite odorless, colorless, and non-abundant in Earth’s atmosphere, isotopes of it can be used for medicinal purposes. The isotope Kr-85 is used in the study of blood flow and lung function problems in nuclear medicine. Magnetic resonance imaging (MRI) machines make use of another one of krypton’s isotopes, Kr-83. This new form of imaging will use treated Kr gas that can be inhaled and used as contrast to reveal areas of the lung on an MRI scan. While traditional MRI scans use the protons in the body as a target to get a picture of tissue, this will not give the best picture of the lungs as they are filled with air. With the use of inhaled hyperpolarized gas MRI machines that use lasers to polarize an inert noble gas, will align the nuclei of the gas, and it will show up on an MRI scan.

Home Insulation

Kr is also used as an insulating gas between window panels. It is commonly recognized as a better insulating agent over its counterpart argon. The use of it in window panels makes for more energy efficient windows, especially for larger windows. Although Kr does cost more than argon, since it is harder to extract, it makes up for that cost over time. A recent study shows that windows using Kr insulation cut energy bills up to 15% per year.

Krypton’s Discovery

On May 30, 1898 Sir William Ramsay, a chemist from Scotland, alongside Morris M. Travers, an english chemist, discovered Krypton. While studying liquid air they found small amounts of liquid krypton were left behind after the more volatile components of liquid air had boiled away.

Krypton Chemistry- Compounds, Reactions, Oxidation States

Chemical Properties

Krypton is a chemical element found in group 18 of the periodic table. This gas is almost three times heavier than air. It is colorless, odorless, tasteless, and monatomic. This gas is also not very reactive since it is a noble gas. It will usually only react with fluorine gas.

Krypton Compounds

Krypton Difluoride

From its discovery most scientists believed that it was impossible for krypton to form compounds until the 1960s when krypton difluoride was discovered. This was the first compound of krypton discovered, it is used as a very strong oxidizing agent KrF2.

Krypton Isolation

It is isolated the same way as any other noble gas, via air liquefaction. This is a process in which air is cooled to low temperatures so that it will condense into a pale blue mobile liquid.

Physical Properties of Krypton

Krypton Symbol: Kr

Melting Point: – 157 °C

Boiling Point: – 153° C

Density: 3.73 10-3 at 20°C

Atomic Mass: 83.80 g.mol -1

Atomic Number: 36

Electronegativity: 3

Classification: Krypton is a noble gas. It is the fourth element in group 18 of the periodic table.

Electron Shell Configuration: [ Ar ] 3d10 4s2 4p6

Isotopes: Kr has 32 different isotopes.

Toxicity: Non-toxic

Where Can I Buy Kr?

Kr is a very rare gas found in Earth’s atmosphere. It is odorless, colorless, tasteless, and non-toxic. The concentration of the element in Earth’s atmosphere is 1.1×10-4 volume percent making it extremely rare. Kr is primarily shipped in gaseous states for excimer lasers, light bulbs, window insulation, and laboratory research. Company’s like Concorde Specialty Gases are the primary merchants of the element krypton.