Share this entry

Share this page

actinium

Line breaks: ac¦tin|ium
Pronunciation: /akˈtɪnɪəm
 
/

Definition of actinium in English:

noun

[mass noun]
The chemical element of atomic number 89, a radioactive metallic element of the actinide series. It is rare in nature, occurring as an impurity in uranium ores. (Symbol: Ac)
Example sentences
  • Along the way, these disintegration series produce radioactive isotopes of protactinium, thorium, actinium, radium, francium, radon, astatine, polonium, bismuth, lead, thallium and mercury.
  • Actinides - the radioactive chemical elements that span from actinium to lawrencium on the periodic table - have generated a great deal of interest in recent years.
  • The first four actinide elements, actinium, thorium, protactinium and uranium are naturally occurring and have been known for a considerable time.

Origin

early 20th century: from Greek aktis, aktin- 'ray' + -ium.

Definition of actinium in:

Share this entry

Share this page

 

What do you find interesting about this word or phrase?

Get more from Oxford Dictionaries

Subscribe to remove ads and access premium resources

Word of the day vigesimal
Pronunciation: ˌvīˈjesəm(ə)l
adjective
relating to or based on the number twenty