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Understanding the element
Thorium (Th) is chemical element 90. It belongs to the actinoids, and its reference state at room temperature is a solid. Those basic facts are a useful starting point for its chemistry and applications.
Where do we encounter it?
In practice, it turns up most often in nuclear energy, alloys and scientific research.
nuclear energyalloysscientific research
Standard atomic weight232.0377(4)
What its position in the table tells us
Thorium sits in period 7 and the F block. That location is useful because neighbouring elements often share trends in valence electrons, oxidation states and bonding behaviour.
Worth remembering
Thorium is radioactive, so its chemistry cannot be separated from nuclear physics and radiation safety
Thorium is radioactive, so its chemistry cannot be separated from nuclear physics and radiation safety