A short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead.
1
A 231Pa reference material has been characterized for amount of protactinium.
2
Scuffles soon arose over who'd first bagged hafnium, protactinium, and technetium.
3
This addition of a proton shifts it to the next element on the table, protactinium-233.
4
They rechristened it protactinium, or "parent of actinium," the element into which it (eventually) decayed.
5
This is also unstable, so the protactinium spits out another electron and transforms into what you started with, uranium-233.
1
I thought that the house we were going to was Pa-boh's house.
2
At Ban Pa In we left the launch to take the train.
3
This was reportedly the second time Pa Michael Obi had been abducted.
4
Poor old Pa was the shining example of masculinity in her eyes.
5
Listen to that, Pa, a post office in four miles of us.