This is a SUPER easy guide on Thorium element.
In fact, the table mentioned below is the perfect information box (Which gives you every single detail about the Thorium element in Periodic table.)
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Thorium Element (Th) Information
|Appearance of Thorium||Silvery-white metallic appearance|
|State of Thorium at STP||Solid|
|Position of Thorium in Periodic table|
Group: actinides, Period: 7, Block: f
|Category of Thorium element|
Inner transition metals
|Atomic number of Thorium, or |
Protons in Thorium
|Neutrons in Thorium||142|
|Electrons in Thorium||90|
|Symbol of Thorium||Th|
|Atomic mass of Thorium|| |
|Electrons arrangement in Thorium|
Bohr model of Thorium
2, 8, 18, 32, 18, 10, 2
|Electronic configuration of Thorium||[Rn] 6d2 7s2|
|Atomic radius of Thorium|
237 picometers (van der Waals radius)
|1st Ionization energy of Thorium||6.08 eV|
|Electronegativity of Thorium|| |
1.3 (Pauling scale)
|Crystal structure of Thorium|
FCC (face centered cubic)
|Melting point of Thorium||2023 K or 1750 °C or 3182 °F|
|Boiling point of Thorium||5061 K or 4788 °C or 8650 °F|
|Density of Thorium||11.725 g/cm3|
|Main isotope of Thorium||232Th|
|Who discovered Thorium and when?|
Jons Jakob Berzelius (in 1829)
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Thorium in Periodic table
Thorium element is in period 7 and in actinides group of the Periodic table. Thorium is the f-block element and it belongs to inner transition metals group.
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Why is Thorium in Period 7?
Let me ask you a question.
How many shells does thorium have?
It’s 7. Right?
You have already seen the bohr model of thorium atom in the above table.
From the Bohr model, it can be found that the number of orbits or shells in thorium is 7. Hence, as thorium has 7 orbits, it lies in period 7 of the Periodic table.
5 Interesting facts about Thorium
Interesting facts about thorium element are mentioned below.
- The name “Thorium” was derived from “Thor” which is the name of the Norse god of thunder.
- The concentration of thorium in the earth’s crust is approximately 6 ppm by weight.
- The Thorium element was discovered by chemist Jons Jakob Berzelius in 1829.
- Thorium is mostly mined from regions of Australia, Canada, United states of America, Russia and India. 
- Thorite, thorianite and monazite are the major minerals which contain thorium in higher concentrations.
Properties of Thorium
The physical and chemical properties of thorium element are mentioned below.
Physical properties of Thorium
Physical properties of thorium are mentioned below.
- Thorium is a solid metal having a silvery-white metallic appearance.
- The melting point of thorium is 1750 °C and its boiling point is 4788 °C.
- The crystal structure of thorium is FCC (face centered cubic).
- Thorium has many isotopes, but out of those isotopes, the most stable isotope is 232Th, which has a half-life of 14 billion years.
- The atomic mass of thorium is 232.04 u and its density is 11.725 g/cm3.
Chemical properties of Thorium
Chemical properties of thorium are mentioned below.
- Thorium reacts with atmospheric oxygen and it tarnishes slowly, which results in a black oxide layer on it.
- Thorium also reacts with hydrogen, sulfur and halogens like fluorine, chlorine, bromine, etc.
- The most common oxidation state of thorium is +4. But apart from this, it also exists in other oxidation states such as +1, +2 and +3.
- The powdered thorium metal is highly reactive and it can even ignite in air.
- The thorium metal shows a slow reaction with water.
- Thorium dissolves in hydrochloric acid.
Uses of Thorium
Uses of thorium are mentioned below.
- Thorium is used as an alloying element with magnesium to increase the strength of magnesium.
- Thorium dioxide (which is a compound of thorium) is added to glass to increase the refractive index of glass.
- Thorium dioxide is also used in manufacturing of ceramics that are resistant to higher temperatures.
- Nowadays, the commercial use of thorium is minimized due to its radioactive nature.
- The heat present inside the earth’s crust is because of thorium as well as uranium.
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