protactinium

American  

[proh-tak-tin-ee-uhm] / ˌproʊ tækˈtɪn i əm /

noun

Chemistry.

1. a radioactive, metallic element. Pa; 91.

---

protactinium British  

/ ˌprəʊtækˈtɪnɪəm /

noun

1. Former name: protoactinium. a toxic radioactive metallic element that occurs in uranium ores and is produced by neutron irradiation of thorium. Symbol: Pa; atomic no: 91; half-life of the most stable isotope, ²³¹ Pa: 32 500 years; valency: 4 or 5; relative density: 15.37 (calc.); melting pt: 1572°C

---

protactinium Scientific  

/ prō′tăk-tĭn′ē-əm /

1. A rare, extremely toxic, radioactive metallic element of the actinide series that occurs in uranium ores. It has 13 known isotopes, the most stable of which is protactinium 231 with a half-life of 32,760 years. Atomic number 91; approximate melting point 1,550°C; specific gravity 15.37; valence 4, 5.

2. See Periodic Table

---

Etymology

Origin of protactinium

First recorded in 1915–20; prot- + actinium

---

Example Sentences

See Examples For:

protactinium

In 1924, they earned their first joint Nobel Prize nomination for their work with the new element protactinium.

From Scientific American ● Sep. 7, 2023

In this process, they produce specific isotopes of other radioactive elements such as thorium, protactinium and radium.

From Salon ● Jun. 17, 2023

Over time, that elemental uranium has partly decayed into thorium and protactinium.

From New York Times ● Sep. 10, 2021

But thorium gloms on to particles more readily than protactinium.

From Science Magazine ● Jun. 30, 2016

Are there planets where the inhabitants proudly display pendants of niobium and bracelets of protactinium, while gold is a laboratory curiosity?

From "Cosmos" by Carl Sagan

Random Word

Spin the wheel and learn a new word!

---