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Understanding the element
Protactinium (Pa) is chemical element 91. 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 scientific research.
scientific research
Standard atomic weight231.03588(1)
What its position in the table tells us
Protactinium 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
Protactinium is radioactive, so its chemistry cannot be separated from nuclear physics and radiation safety
Protactinium is radioactive, so its chemistry cannot be separated from nuclear physics and radiation safety