Krypton Chemical Properties (25 Facts You Should Know)

Kr or krypton is a colorless, odorless element found in trace amounts in the atmosphere. Let us predict the chemical properties of krypton.

Krypton is a noble gas having a fully completed valence orbital. It can be used in photography like other noble gas. Due to the spectral intensity, it can be used in fluorescent lamps which are white in color. The intense spectral line of krypton is used in laser flux spectroscopy.

In this article, we will discuss different physical as well as chemical properties of krypton like oxidation number, allotrope, isotope, ionization energy, melting, and boiling point.

1. Krypton symbol

The atomic symbol of Krypton is “Kr” which comes from the English alphabet. As K is taken for Kalium or Potassium in alkali metal, “Kr” is used instead of Kr for the abbreviation of Krypton as an atomic symbol.

2. Krypton group in the periodic table

The group of Krypton in the periodic table is 18 because it is a noble gas. So, it is placed in the 18th group as an element. In the Mendeleev periodic table, it is group 18 but in the modern periodic table, it is placed as the VIIIA group as per the precipitation table.

3. Krypton period in the periodic table

Krypton belongs to period 4 in the periodic table because it has more than 18 electrons in the valence shell. Up to period 3, there will be 18^th elements that are well placed, so the remaining 18 electrons get the 4^th period after the transition element.

4. Krypton block in the periodic table

Krypton is a p-block element because the valence electrons are present in the p orbital. Kr also has s, and d orbitals but the outermost electrons are present in the 4p orbital according to the Aufbau principle.

5. Krypton atomic number

The atomic number of Krypton is 36, which means it has 36 protons because the number of protons is always equal to the number of electrons. For this reason, they become neutral due to the neutralization of equal and opposite charges.

6. Krypton atomic Weight

The atomic weight of Krypton is 84 on the ¹²C scale which means the weight of Krypton is the 84/12^th part of the weight of the carbon element. The original atomic weight of Krypton is 83.798. It is because the atomic weight is the average weight of all the isotopes of the element.

7. Krypton Electronegativity according to Pauling

The electronegativity of Krypton is 3 according to the Pauling scale, which means it has electronegative nature and can attract electrons toward itself. The group 18^th element has a higher electronegativity than the previous group’s halogen element.

8. Krypton atomic Density

The atomic density of Krypton is 3.19 g/cm³ which can be calculated by dividing the mass of Krypton by its volume. Atomic density means the number of atoms present per unit volume but the atomic number is the number of electrons present in the valence and inner orbital.

• Density is calculated by the formula, atomic density = atomic mass / atomic volume.
• The atomic mass or weight of Krypton is 289 g
• The volume of the Krypton molecule is 22.4 liter at STP as per Avogardo’s calculation
• So, the atomic density of Krypton is, 293/ (22.4) = 13.08 g/cm³

9. Krypton melting point

The melting point of Krypton is -157.4⁰C or 115.6K temperature because at room temperature Krypton exists in gaseous state. It needs less energy to melt the crystal into a liquid. By increasing the temperature, the elements can be placed in good arrangement.

10. Krypton boiling point

The boiling point of Krypton is -153.40C or 119.6K because it exists in gaseous form at room temperature.

11. Krypton Van der Waals radius

The van der Waal’s radius of Krypton is 202 pm because it has 4s and a filled 3d orbital so it has a strong screening effect. For this reason, the nucleus attraction force for the outermost orbital increases, and this decreases the radius.

• Van der Waal’s radius is calculated by the mathematical formula considering the distance between two atoms, where atoms are spherical in shape.
• Van der Waal’s radius is, R_v = d_A-A / 2
• Where R_V stands for Van Waal’s radius of the molecule of spherical shape
• d_A-A is the distance between two adjacent spheres of the atomic molecule or the summation of a radius of two atoms.

12. Krypton ionic radius

The ionic radius of Krypton is 202 pm which is the same as the covalent radius because for Krypton the cation and anion are the same and it is not an ionic molecule. Rather, it forms by the covalent interaction between two Krypton atoms.

13. Krypton isotopes

Elements having the same number of electrons but different mass numbers are called isotopes of the original element. Let us discuss the isotopes of Krypton.

Although Krypton is inert, it has 33 isotopes which are listed below-

• ⁶⁹Kr
• ⁷⁰Kr
• ⁷¹Kr
• ⁷²Kr
• ⁷³Kr
• ^73mKr
• ⁷⁴Kr
• ⁷⁵Kr
• ⁷⁶Kr
• ⁷⁷Kr
• ⁷⁸Kr
• ⁷⁹Kr
• ^79mKr
• ⁸⁰Kr
• ⁸¹Kr
• ^81mKr
• ⁸²Kr
• ⁸³Kr
• ^83m1Kr
• ^83m2Kr
• ⁸⁴Kr
• ^84mKr
• ⁸⁵Kr
• ^85m1Kr
• ^85m2Kr
• ⁸⁶Kr
• ⁸⁷Kr
• ⁸⁸Kr
• ⁸⁹Kr
• ⁹⁰Kr
• ⁹¹Kr
• ⁹²Kr
• ⁹³Kr
• ⁹⁴Kr
• ⁹⁵Kr
• ⁹⁶Kr
• ⁹⁷Kr
• ⁹⁸Kr
• ⁹⁹Kr
• ¹⁰⁰Kr
• ¹⁰¹Kr
• ¹⁰²Kr

The 9 stable isotopes of Krypton are discussed below –

Isotope	Natural Abundance	Half-life	Emitting particles	No. of Neutron
78Kr	0.36%	9.21*1021 y	€€	42
79Kr	Synthetic	35 hrs	€, γ, β	43
80Kr	2.29%	stable	N/A	44
81Kr	trace	2.3*1019 y	€, γ	45
82Kr	11.59%	stable	N/A	46
83Kr	11.50%	stable	N/A	47
84Kr	56.99%	stable	N/A	48
85Kr	Synthetic	11 y	β	49
86Kr	17.28%	stable	N/A	50

Among those stable isotopes, ⁷⁹Kr and ⁸⁵Kr are synthetic isotopes, and the rest occurs naturally.

14. Krypton electronic shell

The shell surrounding the nucleus as per principal quantum number and holding the electrons is called an electronic shell. Let us discuss the electronic shell of Krypton.

The electronic shell distribution of Krypton is 2 8 18 8 because it has s, p, and d orbitals around the nucleus. Since it has more than 18 electrons and to arrange 36 electrons, it needs 1s, 2s, 2p, 3s, 3p, 3d, and 4s orbitals.

15. Krypton electron configurations

The electronic configuration of Krypton is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ because it has 36 electrons and those electrons should be placed to the nearest orbital of the nucleus s, p, d orbitals and for the 1^st,2^nd, 3^rd, 4^th orbitals.

• Due to exchange energy, electrons enter first in 4s orbital then 3d.
• Where the first number stands for the principal quantum number
• The letter is for orbital and the suffix number is the number of electrons.
• But many elements have more principal quantum numbers depending on the number of electrons.
• Kr has 18 electrons, so the remaining electrons are present after the noble gas configuration.
• So, it is denoted as [Kr]3d¹⁰4s²4p⁶.

16. Krypton energy of first ionization

The first ionization value for Krypton is 1350.8 KJ/mol because the electron is removed from the fully-filled 4p orbital. So, the removal of the first electron for any noble gas disturbs the stability. So it requires more energy and for this reason, the first ionization energy of every noble gas is expected to be high.

17. Krypton energy of second ionization

The 2^nd ionization energy of Krypton is 2350.4 KJ/mol because, in the 2^nd ionization, electrons are removed from the 4p orbital. Upon 2^nd ionization, Kr does not lose its stability but the 2^nd electron is removed from the excited state so it require much energy.

18. Krypton energy of third ionization

The third ionization energy for Krypton is 3565 KJ/mol because the third ionization occurs from 4p orbital and gets stabilization due to half-filled orbital but the value is higher than expected because

• Kr has also a 3d orbital which is subject to poor shielding effect and for this reason also nucleus attraction force on the outer electrons will be increased and the removal of the electron requires a larger amount of energy.
• The 4s orbital of Kr has a strong shielding effect.

19. Krypton oxidation states

The stable oxidation of Kr is O as it is a noble gas. Therefore, it has a filled valence orbital but it also shows a +1, +2, and +3 oxidation state depending upon the molecule formation with electronegative atoms. But those oxidation states are found very rare.

20. Krypton CAS number

The CAS number of the Krypton molecule is 7439-90-9, which is given by the chemical abstracts service.

21. Krypton Chem Spider ID

The Chem Spider ID for Krypton is 94615. By using this number, we can evaluate all the chemical data related to the Krypton atom.

22. Krypton allotropic forms

Allotropes are elements or molecules with similar chemical properties but different physical properties. Let us discuss the allotropic form of Krypton.

Krypton has no allotropes because it is a noble inert gas that has a filled valence shell. Due to more stability, it does not show catenation property.

23. Krypton chemical classification

Krypton is classified into the following categories:

• Kr is a noble inert element
• Kr is a gaseous element
• Kr is a very stable element

24. Krypton state at room temperature

Krypton exists in a gaseous state at room temperature because it has lower van der Waal’s interaction. In the crystal form, it adopts face-centered cubic so the atoms exist very close to each other. The randomness of the atom is very high at room temperature.

25. Is Krypton paramagnetic?

Paramagnetism is the tendency of magnetization in the direction of the magnetic field. Let us see whether Krypton is paramagnetic or not.

Krypton is not paramagnetic rather it is diamagnetic because all the electrons in the valance orbitals are in paired form. It has a molar susceptibility value of -28.6* 10^-6 cm³/mol.

Conclusion

Krypton is a noble inert element. It does not participate in other reactions. In spectroscopy, krypton light has many spectral lines and the wavelength of those lines are more dense and high.