Page 17 - Curriculum Visions Dynamic Book

Actinium (Ac)
Element 89. It is a radioactive element in the actinide series in the Periodic Table.
This rare, silvery-white metal glows blue in the dark.Actinium is one of the decay products of uranium, decaying further to thorium-227 and to radium-223. Actinium is chemically similar
to other rare earths, particularly to lanthanum.Actinium is 150 times more radioactive than radium and is an important element for the production of neutrons.
Discovery
Actinium was discovered in 1899 by André-Louis Debierne while he was trying to find ways to separate rare oxides. It was isolated independently in 1902
by F. Giesel.
Technology
It is a powerful source of alpha rays.As a highly radioactive element, it has limited uses. Actinium is, however, a concentrated form of radioactivity and is used in nuclear power plants and as a source
of neutrons in physics experiments.
Geology
Actinium is found together with uranium in ores such as pitchblende.
It appears in extremely small amounts even in its natural ores, there being less than a ten-millionth part of actinium in pitchblende.
Biology
Actinium is not found naturally in living things. Its low concentration
in nature means that it is never naturally a health hazard. However, its radioactivity makes it highly dangerous in concentrated form.
Key facts...
Name: actinium
Symbol: Ac
Atomic number: 89
Atomic weight: 227
Position in Periodic Table: inner transition metal;
period 7 (actinide series)
State at room temperature: solid
Colour: silvery-white
Density of solid: 10.07 g/cc
Melting point: 1,050°C
Boiling point: 3,200°C
Origin of name: from the Greek word aktinos,
meaning ray
Shell pattern of electrons:
2–8–18–32–18–9–2
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