Rubidium Chemical Properties (25 Facts You Should Know)

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Rb or Rubidium is the alkali metal element that can be placed after Rubidium in the periodic table. We will discuss about rubidium in detail.

Rubidium is silvery white metal, but it is a soft metal and ductile. Rubidium is the 2nd electropositive stable alkali metal. The ore of the rubidium is lepidolite and the molecular formula is K(Li, Al)3(Al, Si, Rb)4O10(F, OH)2. It contains 3.5% of rubidium in the form of oxide.

The thermal conductivity and electrical resistivity of rubidium are very high. Now we will discuss the basic chemical properties of rubidium with proper explanation in the following article.

1. Rubidium symbol

The atomic symbol is that to express an atom by one or two letters and for a molecule, it should be called a molecular symbol. Let us predict the atomic symbol of Rubidium.

The atomic symbol of Rubidium is “Rb” as the name start with the English alphabet “Rb”. Because R represents the alkyl group in organic chemistry, so we use the first two letters of the English alphabet of the rubidium.

2. Rubidium group in the periodic table

A column of the periodic table where the element is placed by the atomic number is called a group. Let us predict the group of Rubidium in the periodic table.

The group of Rubidium in the periodic table is 1. Because it is an alkali metal itself, it can easily form cations by donating an electron. So, it is placed in the 1st group as an element.

3. Rubidium period in the periodic table

The horizontal rows of the periodic table are called a period and correspond to the successive occupation of orbitals of the valence shell. Now predict the period of the Rubidium.

Rubidium is belonged to period 5 in the periodic table because it has more than 36 electrons in the valence shell so it is placed in the fourth position of the periodic table in the period and also in the group.

4. Rubidium block in the periodic table

The block of the periodic table is known as the set of atomic orbitals of an element where the valence electrons are lying. Let us predict the block of the Rubidium.

Rubidium is an s block element because the valence electrons present in the orbital is s or the outermost orbital of the Rubidium is s, so it belongs to s block element like alkali metals. There are only four blocks present in the periodic table, they are s,p,d, and f according to the orbitals.

5. Rubidium atomic number

The number of protons present in the nucleus is called the atomic number of that particular element. Let us find the atomic number of the Rubidium.

The atomic number of Rubidium is 37, which means it has 37 protons and also it has only 37 electrons because we know the number of protons is always equal to the number of electrons and for this reason, they become neutral due to the neutralization of equal and opposite charges.

6. Rubidium atomic weight

Atomic weight is the mass of one atom of that particular element of the ratio of some standard value. Let us calculate the atomic weight of Rubidium.

The atomic weight of rubidium on the 12C scale is 85 which means the weight of Rubidium is the 85/12th part of the weight of the carbon element. The original atomic weight of Rubidium is 85.4678, it is because the atomic weight is the average weight of all the isotopes of the element.

7. Rubidium Electronegativity according to Pauling

According to Pauling electronegativity is defined as the power of an atom in a molecule to attract electrons to itself. Let us predict the electronegativity of Rubidium.

The electronegativity of Rubidium according to the Pauling scale is 0.82, which means it is more electropositive in nature and can attract electrons towards itself. The most electronegative atom as per the Pauling scale in the periodic table is fluorine having 4.0 electronegativity.

8. Rubidium atomic density

The atomic density is the number of atoms or nuclides per cm3 or in a unit volume of atoms in a material. Let us calculate the atomic density of Rubidium.

The atomic density of Rubidium is 1.53 g/cm3 which can be calculated the diving the mass of the Rubidium 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 the Rubidium atom is 85.4678 g
  • The volume of the Rubidium molecule is 22.4 liter at STP as per Avogardo’s calculation
  • So, the atomic density of the Rubidium atom is, 85.4678/(2*37) = 1.1549g/cm3

9. Rubidium melting point

The point where a substance changes its solid state to a liquid or the temperature where the change occurs as atmospheric pressure. Let us find the melting point of the Rubidium atom.

The melting point of the Rubidium atom is 39.480 C or 312.48 K temperature because at room temperature Rubidium exists as a solid form where all the atoms in the Rubidium lie in an ordered manner due to higher energy, so if we increase the temperature then the elements are placed in good arrangement.

10. Rubidium boiling point

The boiling point is where the vapor pressure of the substance becomes equal to the atmospheric pressure. Let us find the boiling point of Rubidium.

The boiling point of the Rubidium atom is 6880 C or 961K because it exists in solid form at room temperature so the boiling point of the Rubidium atom is also very high even at very high positive temperature.

 The van der Waal’s force of attraction is low so high energy of heat is required for the boiling Rubidium. The solid form of Rubidium exists at room temperature or higher temperature from its melting point.

11. Rubidium Van der Waals radius

Van der Waal’s radius is the imaginary measurement between two atoms where they are not bound ionically or covalently. Let us find van der Waal’s radius of Rubidium.

The van der Waal’s radius of the Rubidium molecule is 303 pm because the value is close to the value of which is proposed by Pauling. Van der Waal’s radius is calculated by the mathematical formula considering the distance between two atoms, where atoms are spheres.

  • The formula used the find out the Van der Waal’s radius is, Rv = dA-A / 2
  • Where RV is the Van Waal’sal’s radius of the molecule
  • dA-A is the summation of the radius of two atomic spheres or the distance between the center of two spheres.

12. Rubidium ionic radius

Ionic radius is the summation of the radius of cation and anion respectively, for an ionic molecule in a crystal structure. Let us find out the ionic radius of Rubidium.

The ionic radius of Rubidium is 303 pm is the same as the covalent radius because for Rubidium the cation and anion are the same and it is not an ionic molecule, rather it forms by the covalent interaction between two Rubidium atoms.

13. Rubidium isotopes

The elements that have same number of protons but different numbers of neutrons of substances are called isotopes of that original element. Let us discuss isotopes of Rubidium.

Rubidium has 37 types of isotopes 71Rb to 107Rb based on neutron and we have discussed only a few which have some relative abundance.

  • 82Rb – It has a half-life of 1.27 mins and emitted β and positron. It is a very unstable radioactive isotope of Rb and does not occur naturally, by made by radioactive decay of 82Sr.
  • 83Rb – it has a half-life more than the previous one 86.2 days it can emit positron.
  • 84Rb –  It has a half-life of 33 days and can emit β,γ, and positron.
  • 85Rb – It is the most stable isotope of the Rb and it has 72.11% abundance on the earth.
  • 86Rb – it has a half-life of almost 19 days and is also a radioactive isotope and can decay.
  • 87Rb – After the 85Rb it is the 2nd abundance (27.83%) isotope of Rb and has a much longer half-life, 4.5*1010 years. It is also a radioactive isotope and can emit β particles.

14. Rubidium electronic shell

Electronic shells are those which are surrounding the nucleus and containing a specific number of electrons in it. Let us discuss the electronic shell of Rubidium.

The number of electronic shells of Rubidium around the nucleus is 6, which is s and p orbitals. Because it has more than 36 electrons and to arrange 37 electrons need 1s,2s,2p, 3s, 3p, 3d, and 4s, 4p orbital as p orbital contains six electrons and s orbital contains two electrons.

15. Rubidium electron configurations

The electronic configuration is an arrangement of the electrons in available orbital by considering Hund’s rule. Let us discuss the electronic configuration of Rubidium.

The electronic configuration of Rubidium is 1s22s22p63s23p6 3d10 4s2 4p65s1 because it has 37 electrons and those electrons should be placed to the nearest orbital of the nucleus s, p, and d orbitals and for the 1st,2nd, 3rd, 4th and 5th orbitals where the principal quantum numbers are 1,2,3,4 and 5.

Here the first number stands for the principle quantum number, the letter is for orbital and the suffix number is the number of electrons.

16. Rubidium energy of first ionization

The energy required for the removal of the last valence electrons from the respective orbital is called the first ionization energy. Let us predict the first ionization of Rubidium.

The first ionization occurs for Rubidium from its 5s orbital to remove one electron. The energy required for the first ionization of a Rubidium atom is 403 KJ/mol because there is lesser energy required removal of electrons from the 4s orbital which is far away from nucleus and the force of attraction is low.

Not necessary to remove electrons always for the s orbital, it depends on the valence orbital, if the valence orbital will be p, d or f then the electron is removed from the p, d, and f orbital respectively.

17. Rubidium energy of second ionization

Second ionization is the removal of the outermost electron from its +1 oxidation state of the element. Let us see the second ionization of Rubidium.

The 2nd ionization energy of Rubidium is 2632 KJ/mol because in the 2nd ionization electron is removed from the filled 4p orbital which needs more energy, and also due to the presence of d electrons, the effective nuclear charge will be increased towards the outermost electrons by the shielding effect.

 After electron removal from electron from the filled 4p then the system will be unstable and energized, so the process is unfavorable, and for this reason, 2nd ionization energy is very high than 1st ionization energy of Rubidium.

18. Rubidium energy of third ionization

Third ionization is the removal of electrons from the respective orbital having a +2 oxidation state of the element. Let us see the third ionization of Rubidium.

The third ionization occurs for the Rubidium from the 4p orbital, and the energy required for this process is 3859 KJ/mol. Because the removal of electrons from the 4p orbital needs more energy than the 4s orbital because it is placed near to nucleus and also the presence of 3d electrons.

19. Rubidium oxidation states

The oxidation state is the charge present over the element after the removal of such numbers of an electron to form a stable bond. Let us predict the oxidation state of Rubidium.

The stable oxidation state of Rubidium is +1 because it has only one electron in the s orbital and when the electron is removed then it can form a stable single bond, so it has +1 oxidation state as the s orbital contains a maximum of two electrons.

20. Rubidium CAS number

CAS registry number is a special kind of number a unique unmistakable identifier number provided worldwide. Let us know the CAS number of Rubidium.

The CAS number of the Rubidium molecule is 7440-17-7, which is given by the chemical abstracts service. It is different from the CAS number of the other element.

The CAS number of K is unique and not matching with the other element’s CAS number.

21. Rubidium ChemSpider ID

The Royal Society of Chemistry gives a particular unique number for every chemical element which is knowns as Chem Spider ID. Let us discuss it for Rubidium.

The Chem Spider ID for Rubidium is 4512975, which is given by the royal society of chemistry, and by using this number we can evaluate all the chemical data related to the Rubidium atom. like CAS number it is also different for all elements.

22. Rubidium allotropic forms

Having the same chemical but different physical properties of different structural forms of the same element. Let us discuss the allotropic form of Rubidium.

There is no allotropic form of Rubidium present in the universe because it does not show catenation properties like carbon.

23. Rubidium chemical classification

Chemical classification is the classified the element by its reactive nature, or they cause hazards to the human body. Let us know the chemical classification of Rubidium.

Rubidium is classified as an alkali metal at room temperature because it can produce heat and electricity also the density of the element is very high and it is more ductile.

24. Rubidium state at room temperature

The condition is characterized by the element at room temperature and experimental pressure. Let us predict the state of Rubidium at room temperature.

Rubidium exists in a solid state at room temperature because it has higher van der Waal’s interaction so the atoms exist very close to each other. The randomness of the atoms is very high at room temperature.

The solid-state of the Rubidium can be changed to liquid or solid at a very low temperature, where the randomness will be decreased for the Rubidium atom.

25. Is Rubidium paramagnetic?

The materials tend to get weakly magnetized in the direction of the magnetizing field when placed in a magnetic field. Let us see whether Rubidium is paramagnetic or not.

The Rubidium atom is paramagnetic in nature, due to the presence of one unpaired electron in its 5s orbital, after the first ionization Rb+ is diamagnetic in nature because all the electrons in the 4p orbitals exist as paired up form.

So, we have to check the number of electrons present in the valence orbital for an element whether it is paired form or unpaired form then it will be paramagnetic or diamagnetic accordingly.

Conclusion

Rb can form superoxide with oxygen molecules because it has a larger size so it can hold more atoms with it. Also, it forms basic hydroxide when it reacted with water molecules. The electron releasing ability of Rb is very high as because it ahs larger size and nuclear attraction for the outermost electrons are very low.