Thorium ( Th )

Define: Thorium is inner transition metal . Place in actinides series. It is  1 element in actinides series. It is slightly radioactive element. It is small amount soft ,malleable . It is mostly similar to lead . It is easily bent ,cut and shaped welder and rolled .it is toxic in nature .it is found from thorite, uranothorite, monazite minerals. It have high melting point

Discovery : Thorium is discovered in 1828 by scientist Jon’s jacob Berzelius.

Origin of name : the name thorium after Thor . It is the Scandinavian god of  War

Physical properties :

Atomic symbol: Atomic symbol of Thorium is Th

Atomic number : Atomic number of thorium is 90

In thorium 90 proton and 90 Electron is present

Atomic weight/ mass: Atomic weight of thorium is 232.04 Amu

In thorium 90 proton and 142 neutron is present

Position : it Is place in periodic table at 7th period and in lanthanide group

Block : it is place in f block

Colour :it show silvery colour

Nature : thorium show solid state in nature

Boiling point : boiling point of Thorium is 4785 0C

Melting point :melting point of Thorium is 1750 0C

Isotopes: thorium show 2 stable isotopes

  • 230Th : atomic weight of this isotope is 230.03 Amu

In this isotope 90 proton ,90 electron and 140 neutron is present

  • 232Th: atomic weight of this isotope is 232.09 Amu

In this isotope 90 proton 90 electron and 142 neutron is present

Chemical properties :

Electronic configuration

Electronic configuration of Thorium is [ Rn ] 6d2 7s2

Electronic configuration in concert of shell is 2,8,18,32,18,10,2

Electronic structure

Valency :valency of Thorium is 4

Atomic radius : Atomic radius of Thorium is 180 Pm


  • Thorium is use to make high quality camera lenses.
  • It’s dioxide form use in making glass for the increasing refractive index
  • It is use as a source of nuclear power
  • It is use as alloying agent in Nuclear Power
  • It is use in portable gas light
  • It is mostly. Use to make hi temperature lab crucible
  • It is use to coat tungsten wire
  • Use in welding rod to make them burn better
  • It oxide form use as catalyst
  • Is use to make improve properties of ophthalmology lesser


Question and Answer:

Q1. Define Thorium

Q2. Who discovered Thorium?

Q2. Physical properties of Thorium

Q4. Write Atomic Symbol of Thorium.

Q5. Write the Atomic number of Thorium.

Q6. On which block Thorium element is present?

Q7. What is the color of Thorium?

Q8. What is the Boiling point of Thorium?

Q9. What is the Melting point of Thorium?

Q10. Write the Isotopes of Thorium.

Q11. Show Electronic configuration of Thorium.

Q12. Write Electronic Structure of Thorium.

Q13. What is the Valency of Thorium?

Q14. Write the uses of Thorium element.

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