Core Concepts
In this article, you will learn about krypton, its chemical properties, and its importance in various applications.
Introduction to Krypton
Stationed in the non-metals category of the periodic table sits the element krypton. Found in Group 18, It is categorized as a noble gas. Not only is this element colorless, but 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. For this reason, 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 former use of krypton was to obtain artificial rubies.
- Kr discharges a greenish-yellow glow when it is mixed with other gases.
- This element and the other Group 18 elements were among the last elements to be discovered.
Krypton 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. A proud member of the noble gas family, it 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°C (-251°F), and a boiling point of -153°C (-243°F).
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.
Krypton Dating
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 common carbon dating technique, krypton dating measures the decay of a radioactive isotope that has constant and known decay rates, and compares it to a stable isotope. Since krypton is a noble gas, it does not interact chemically with other elements. It 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 (krypton-81) which decays slowly, and a stable isotope (krypton-83) which does not decay. Comparing the proportion of stable-to-radioactive isotopes estimates the age of the ice. With this new technique, researchers believe that they may be able to date ice up to 1.5 million years in the past.
Deep Mantle Krypton
Using the different isotopes of krypton, scientists are able to create a sort of chemical fingerprint that displays the ingredients that made the earth. Krypton 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 Galápagos Islands and Iceland reveal a clearer picture of how our planet was created. The findings indicate that Earth’s volatile elements arrived as Earth was growing and shaping itself as a planet. This information is important because it contradicts the alternative theory that Earth’s volatile elements were mostly delivered near the end of the planet’s formation. The isotopes suggest that planetesimals (minute planets) from the outer solar system bombarded Earth early on.
Krypton in Today’s World
Photography
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 up to 40% efficient, but it needs at least a 70% increase in pressure over xenon to achieve a more efficient flash.
Medical Diagnosis
While krypton is odorless, colorless, and non-abundant in Earth’s atmosphere, isotopes of it can be used for medicinal purposes. The isotope krypton-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 of krypton’s isotopes, krypton-83. This form of imaging uses treated krypton 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 does 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 align the nuclei of the gas, and it will show up on an MRI scan.
Home Insulation
Krypton 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 krypton does cost more than argon since it is harder to extract, it makes up for that cost over time by potentially cutting energy bills.
Krypton’s Discovery
On May 30, 1898, Scottish chemist Sir William Ramsay, alongside English chemist Morris M. Travers, discovered Krypton. While studying liquid air, they found that small amounts of liquid krypton were left behind after the more volatile components of liquid air had boiled away.
Krypton Chemistry: Compounds, Reactions, and 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. This changed in 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
Krypton 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
Symbol: Kr
Melting point: -157°C (-251°F)
Boiling point: -153°C (-243°F)
Density: 3.73 * 10-3 g/cm3 at 20°C (68°F)
Atomic mass: 83.80 g/mol
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] 3d104s24p6
Isotopes: Kr has 32 different isotopes.
Toxicity: Non-toxic.