Home


  About This Site

  Comments

  Help

  Links



  Window Version


 Show Table With:

    Name

    Atomic Number

    Atomic Mass

    Electron Configuration

    Number of Neutrons

    Melting Point

    Boiling Point

    Date of Discovery

    Crystal Structure


 Element Groups:

    Alkali Metals

    Alkaline Earth Metals

    Transition Metals

    Other Metals

    Metalloids

    Non-Metals

    Halogens

    Noble Gases

    Rare Earth Elements


 


Krypton at Chemical Elements.com


Basic Information | Atomic Structure | Isotopes | Related Links | Citing This Page





Basic Information

Name: Krypton

Symbol: Kr

Atomic Number: 36

Atomic Mass: 83.8 amu

Melting Point: -157.2 °C (115.950005 K, -250.95999 °F)

Boiling Point: -153.4 °C (119.75001 K, -244.12 °F)

Number of Protons/Electrons: 36

Number of Neutrons: 48

Classification: Noble Gas

Crystal Structure: Cubic

Density @ 293 K: 3.74 g/cm3

Color: colorless gas



Atomic Structure




[Bohr Model of Krypton] 

Number of Energy Levels: 4


    First Energy Level: 2

    Second Energy Level: 8

    Third Energy Level: 18

    Fourth Energy Level: 8


Isotopes

IsotopeHalf Life
Kr-78Stable
Kr-791.45 days
Kr-80Stable
Kr-81210000.0 years
Kr-82Stable
Kr-83Stable
Kr-83m1.86 hours
Kr-84Stable
Kr-8510.73 years
Kr-85m4.48 hours
Kr-86Stable
Kr-871.27 hours
Kr-882.84 hours
Kr-893.15 minutes
Kr-9032.3 seconds

Facts

Date of Discovery: 1898

Discoverer: Sir William Ramsay

Name Origin: From the Greek word kryptos (hidden)

Uses: Lighting

Obtained From: production of liquid air

Related Links

None Available.

MLA Format for Citing This Page

Bentor, Yinon. Chemical Element.com – Krypton.

<http://www.chemicalelements.com/elements/kr.html>.


For more information about citing online sources, please visit the MLA’s Website .




This page was created by Yinon Bentor.

Use of this web site is restricted by this site’s license
agreement .
Copyright © 1996-2012 Yinon Bentor. All Rights Reserved.


250 thistle logo

ENCYCLOPÆDIA BRITANNICA

250 thistle logo

START YOUR FREE TRIAL

Advertisement

Log In · Join

  • Demystified
  • Quizzes
  • Galleries
  • Lists
  • On This Day
  • Biographies
  • Newsletters

START YOUR FREE TRIAL

Advertisement

Search Britannica

What are you looking for?
Browse popular topics:
  • Chile earthquake of 1960
  • Ming dynasty
  • Chemical reaction
  • Boxer Rebellion
  • Pompeii

Bring fact-checked results to the top of your browser search.
Learn More.

chrome store logo



Krypton

chemical element
Written By:

  • Gary J. Schrobilgen
See Article History

Alternative Title:
Kr

Krypton (Kr), chemical element , rare gas of Group 18 ( noble gases ) of the periodic table , which forms relatively few chemical compounds . About three times heavier than air , krypton is colourless, odourless, tasteless, and monatomic. Although traces are present in meteorites and minerals , krypton is more plentiful in Earth’s atmosphere , which contains 1.14 parts per million by volume of krypton. The element was discovered in 1898 by the British chemists Sir William Ramsay and Morris W. Travers in the residue left after a sample of liquid air had boiled almost entirely away.

Element Properties
atomic number36
atomic weight83.80
melting point−156.6 °C (−249.9 °F)
boiling point−152.3 °C (−242.1 °F)
density (1 atm, 0 °C [32 °F])3.733 g/litre (0.049 ounce/gallon)
oxidation numbers 0, 2
electron config.(Ar)3d104s24p6
Read More on This Topic

Apparatus used in the isolation of argon by English physicist Lord Rayleigh and chemist Sir William Ramsay, 1894Air is contained in a test tube (A) standing over a large quantity of weak alkali (B), and an electric spark is sent across wires (D) insulated by U-shaped glass tubes (C) passing through the liquid and around the mouth of the test tube. The spark oxidizes the nitrogen in the air, and the oxides of nitrogen are then absorbed by the alkali. After oxygen is removed, what remains in the test tube is argon.

noble gas

(Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og). The noble gases are colourless, odourless, tasteless, nonflammable gases. They traditionally have been labeled Group 0 in the periodic table because for decades after their discovery it was believed that

Properties of the element

Because its boiling point (−152.3 °C, or −242.1 °F) is about 30–40 °C (50–70 °F) higher than those of the major constituents of air, krypton is readily separated from liquid air by fractional distillation; it accumulates along with xenon in the least volatile portion. These two gases are further purified by adsorption onto silica gel , redistillation, and passage over hot titanium metal , which removes all impurities except other noble gases.

Krypton is used in certain electric and fluorescent lamps and in a flashlamp employed in high-speed photography . Radioactive krypton-85 is useful for detecting leaks in sealed containers, with the escaping atoms detected by means of their radiation . Krypton is named from the Greek word kryptos, “hidden.”

When a current of electricity is passed through a glass tube containing krypton at low pressure , a bluish white light is emitted. The wavelength of an orange-red component of light emitted by stable krypton-86, because of its extreme sharpness, served from 1960 to 1983 as the international standard for the metre . (One metre equaled 1,650,763.73 times the wavelength of this line.)

Natural krypton is a mixture of six stable isotopes : krypton-84 (57.0 percent), krypton-86 (17.3 percent), krypton-82 (11.6 percent), krypton-83 (11.5 percent), krypton-80 (2.25 percent), and krypton-78 (0.35 percent). Krypton has isotopes of every mass number from 69 through 100; of these isotopes; twenty-five are radioactive and are produced by fission of uranium and by other nuclear reactions . The longest lived of these, krypton-81, has a half-life of 229,000 years. After it has been stored a few days, krypton obtained by nuclear fission contains only one radioactive isotope , krypton-85, which has a half-life of 10.8 years, because all the other radioactive isotopes have half-lives of 3 hours or less.

Compounds

Krypton is the lightest of the noble gases that form isolable chemical compounds in macroscopic amounts. For many years it was considered to be totally unreactive. In the early 1960s, however, krypton was found to react with the element fluorine when both are combined in an electrical-discharge tube at −183 °C (−297 °F); the compound formed is krypton difluoride, KrF2. Several other methods for the synthesis of KrF2 are now known, including irradiation of krypton and fluorine mixtures with ultraviolet radiation at −196 °C (−321 °F).

KrF2 is a colourless crystalline solid that is highly volatile and slowly decomposes at room temperature. No other molecular fluoride of krypton has been isolated, so all krypton compounds are derived from KrF2, where Kr is in the +2 oxidation state . Krypton difluoride is a powerful oxidative fluorinating agent. (Its oxidizing power means that it extracts electrons from other substances and confers on them a positive charge. Its fluorinating ability means that it transfers an F ion to other substances. Hence, in a formal sense, oxidative fluorination is the net result of extraction of two electrons and addition of F; this can be considered to be equivalent to the transfer of F+.) KrF2 is, for example, capable of oxidizing and fluorinating xenon to XeF6 and gold to AuF5.

The cationic species KrF+ and Kr2F3+ are formed in reactions of KrF2 with strong fluoride-ion acceptors such as the pentafluorides of Group 15, in which the fluoride ion F is transferred to the pentafluoride to give complex salts that are analogous to those of XeF2; here no oxidation is involved. Among these complex salts are [KrF+][SbF6] and [Kr2F3+][AsF6]. The Kr2F3+ cation is V-shaped with a fluorine atom bonded to each of two krypton atoms and both krypton atoms bonded to a common fluorine in the middle, i.e., F(KrF)2+.

The KrF+ cation ranks among the most powerful chemical oxidizers presently known and is capable of oxidative fluorination of gaseous xenon to XeF5+ and chlorine , bromine , and iodine pentafluorides to the ClF6+, BrF6+, and IF6+ cations, respectively. The KrF+ cation behaves as only an oxidizing agent in converting gaseous oxygen to O2+.

The KrF+ cation has been shown to behave as a Lewis acid ( electron -pair acceptor) toward a number of Lewis bases that are resistant to oxidation by the strongly oxidizing KrF+ cation at low temperatures. These Lewis acid-base adducts are exemplified by HCNKrF+ and F3CCNKrF+, which are formed as AsF6 salts. Such cations are the only known examples of krypton bonded to nitrogen . The compound Kr(OTeF5)2 is the only reported example of a compound in which krypton is bonded to oxygen. No compounds in which krypton is bonded to elements other than fluorine, oxygen, and nitrogen have been isolated.

Clathrate “compounds,” in which the element is trapped in cagelike structures of water or other molecules, are known. There is no diatomic molecule of krypton.

Gary J. Schrobilgen

Learn More in these related Britannica articles:

  • Apparatus used in the isolation of argon by English physicist Lord Rayleigh and chemist Sir William Ramsay, 1894Air is contained in a test tube (A) standing over a large quantity of weak alkali (B), and an electric spark is sent across wires (D) insulated by U-shaped glass tubes (C) passing through the liquid and around the mouth of the test tube. The spark oxidizes the nitrogen in the air, and the oxides of nitrogen are then absorbed by the alkali. After oxygen is removed, what remains in the test tube is argon.

    noble gas
    (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og). The noble gases are colourless, odourless, tasteless, nonflammable gases. They traditionally have been labeled Group 0 in the periodic table because for decades after their discovery it was believed that…
  • crystal bonding

    chemical bonding: Potassium through krypton
    …to the next noble gas, krypton. The presence of the 3d orbitals in the scheme of occupation lengthens the fourth row of the periodic table from 8 to 18 members, and the row from potassium to krypton is called the first long period of the periodic table.…
  • The Balmer series of hydrogen as seen by a low-resolution spectrometer.

    spectroscopy: RIS schemes
    For example, the inert element krypton has an ionization potential of 14.0 electron volts and requires a more elaborate RIS scheme of the type shown in Figure 14B. The first step is a resonance transition at the wavelength of 116.5 nanometres, followed by a second resonance step at 558.1 nanometres.…
  • Figure 1: Unit cells for face-centred and body-centred cubic lattices.

    crystal: Structures of metals
    solids neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe). Their melting temperatures at atmospheric pressure are: Ne, 24.6 K; Ar, 83.8 K; Kr, 115.8 K; and Xe, 161.4 K.…
  • The atmospheres of planets in the solar system are composed of various gases, particulates, and liquids. They are also dynamic places that redistribute heat and other forms of energy. On Earth, the atmosphere provides critical ingredients for living things. Here, feathery cirrus clouds drift across deep blue sky over Colorado's San Miguel Mountains.

    atmosphere
    …neon (Ne), helium (He), and krypton (Kr) and other constituents such as nitrogen oxides, compounds of sulfur, and compounds of ozone are found in lesser amounts.…

ADDITIONAL MEDIA

  • First ionization energies of the elements.

More About Krypton

7 references found in Britannica articles

Assorted References

    • major reference
      • In noble gas
    • Earth atmosphere
      • In atmosphere
    • lasers
      • In laser: Types of lasers
    • work of Ramsay
      • In Sir William Ramsay: Discovery of noble gases

    properties and structure

      • Aufbau principle
        • In chemical bonding: Potassium through krypton
      • crystal structure
        • In crystal: Structures of metals
      • resonance ionization
        • In spectroscopy: RIS schemes

      Additional Reading

      External Websites

      • Los Alamos National Laboratory – Krypton
      • WebElements – Krypton
      • Chemicool – Krypton
      • Rader’s Chem4Kids.com – Krypton
      • Royal Society of Chemistry – Krypton
      Britannica Websites
      Articles from Britannica Encyclopedias for elementary and high school students.
      • krypton – Student Encyclopedia (Ages 11 and up)

      Article History

      Article Contributors


      Feedback

      Corrections? Updates? Help us improve this article!
      Contact our editors with your feedback.



      Krypton
      Chemical element

      chemical properties of Krypton (part of Periodic Table of the Elements imagemap)


      View All Media

      key people
      • Sir William Ramsay
      related topics
      • Chemical element
      • Noble gas
      • Air
      • Krypton-81



      Similar Topics
      • Hydrogen
      • Carbon
      • Sodium
      • Nitrogen
      • Sulfur
      • Phosphorus
      • Boron
      • Iodine
      • Fluorine
      • Zinc



      Featured On Britannica
      • Demystified / Arts & Culture

        What’s Inside the Great Pyramid?

        pyramid sunset, egypt

      • Companion / History

        Pearl Harbor in Context

        pg 159Explosions rock American base at Pearl Harbor following surprise Japanese attack, December 7, 1941.To Japan, an eventual attack on the United States, specifically on the island outpost of Hawaii, was aninevitable beginning of military action agains

      • Demystified / Health & Medicine

        Are There Really Right-Brained and Left-Brained People?

        Illustration of human head with brain waves (medicine, medical, anatomy).

      • Demystified / Animals

        How Did the Sperm Whale Get Its Name?

        Submerged sperm whale off east Sri Lanka coast, mammal



      Britannica Lists & Quizzes
      • Musical instruments

        Music Quiz

        Australian Popular Music

      • Meeting of leaders in W.W.I, General Hindenburg, Kaiser William II, General Ludendorff examine maps during World War I in Germany.

        History List

        Military Commanders of World War I

      • tennis racket and tennis ball

        Sports & Recreation Quiz

        Australian Open

      • German machine gunners occupy a trench during World War I.

        History List

        Weapons of World War I

      • Introduction
      • Properties of the element
      • Compounds

      Edit Mode

      Krypton
      Chemical element



      Tips For Editing

      We welcome suggested improvements to any of our articles. You can make it easier for us to review and, hopefully, publish your contribution by keeping a few points in mind.

      1. Encyclopædia Britannica articles are written in a neutral objective tone for a general audience.
      2. You may find it helpful to search within the site to see how similar or related subjects are covered.
      3. Any text you add should be original, not copied from other sources.
      4. At the bottom of the article, feel free to list any sources that support your changes, so that we can fully understand their context. (Internet URLs are the best.)

      Your contribution may be further edited by our staff, and its publication is subject to our final approval. Unfortunately, our editorial approach may not be able to accommodate all contributions.


      Thank You for Your Contribution!

      Our editors will review what you’ve submitted, and if it meets our criteria, we’ll add it to the article.

      Please note that our editors may make some formatting changes or correct spelling or grammatical errors, and may also contact you if any clarifications are needed.

      Uh Oh

      There was a problem with your submission. Please try again later.



      Keep Exploring Britannica

      A series of photographs of the Grinnell Glacier taken from the summit of Mount Gould in Glacier National Park, Montana, in 1938, 1981, 1998, and 2006 (from left to right). In 1938 the Grinnell Glacier filled the entire area at the bottom of the image. By 2006 it had largely disappeared from this view.

      Climate change
      Climate change, periodic modification of Earth’s climate brought about as a result of changes in the…

      Read this Article

      Building knocked off its foundation by the January 1995 earthquake in Kōbe, Japan.

      Earthquake
      Earthquake, any sudden shaking of the ground caused by the passage of seismic waves through Earth’s rocks.…

      Read this Article

      Margaret Mead

      Education
      Education, discipline that is concerned with methods of teaching and learning in schools or school-like…

      Read this Article



      250 thistle logo

      Menu
      • Home
      • Demystified
      • Quizzes
      • Galleries
      • Lists
      • On This Day
      • Biographies
      • Newsletters

      • Login
      • Join

      Contents

      Contents

      Krypton
      chemical element
      View All Media

      (2 Images)

      Media

      Print
      Print

      Please select which sections you would like to print:

      Cite

      Share
      Share

      Facebook

      Twitter

      Google+

      LinkedIn

      Email

      Feedback
      Thank you for your feedback

      Our editors will review what you’ve submitted and determine whether to revise the article.

      Join Britannica’s Publishing Partner Program and our community of experts to gain a global audience for your work!

      share

      Share
      Share

      Facebook

      Twitter

      Google+

      LinkedIn

      Email

      Email this page

      ×

      Download our free Chrome extension, Britannica Insights.

      Britannica Insights screenshot

      Facts matter and Britannica Insights makes it easier to find them.

      Install for Chrome Now

      Learn more