WebElements Periodic Table » Actinium (original) (raw)
Actinium - 89Ac: the essentials
Name: actinium
Symbol: Ac
Atomic number: 89
Relative atomic mass (_A_r): [ 227 ] (longest lived isotope)
Standard state: solid at 298 K
Appearance: silvery
Classification: Metallic
Group name: Actinoid
Period in periodic table: 7 (actinoid)
Shell structure: 2.8.18.32.18.9.2
CAS Registry: 7440-34-8
Actinium atoms have 89 electrons and the shell structure is 2.8.18.32.18.9.2. The ground state electronic configuration of neutral actinium is [Rn].6d1.7s2 and the term symbol of actinium is 2D3/2.
Actinium: description
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Actinium is dangerously radioactive. The chemical behaviour of actinium is similar to that of the rare earths, particularly lanthanum. It is found naturally in uranium ores and actinium is 150 times more radioactive than radium.
This sample of uraninite contains some about 10-9 grammes of actinium at any one time. Image adapted with permission from Prof James Marshall's (U. North Texas, USA) Walking Tour of the elements CD.
Actinium: binary compounds
Binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and other compounds of actinium where known.
Actinium: compound properties
Bond strengths; lattice energies of actinium halides, hydrides, oxides (where known); and reduction potentials where known.