Actinium

Radium - Actinium - Thorium
La Ac
	Full table

General

Name, Symbol, Number

actinium, Ac, 89

Chemical series

Actinides

Group, Period, Block

3 , 7 , f

Density, Hardness

10070 kg/m³, n/a

Appearance

silvery

Atomic Properties

Atomic weight

(227) amu

Atomic radius (calc.)

195 (n/a) pm

Covalent radius

n/a pm

van der Waals radius

n/a pm

Electron configuration

[Rn]6d6d¹7s²

e^- 's per energy level

2, 8,18,32,18, 9, 2

Oxidation states (Oxide)

3 (neutral)

Crystal structure

face centered cubic

Physical Properties

State of matter

solid (__)

Melting point

1323 K (1922 �F)

Boiling point

3473 K (5792 �F)

Molar volume

22.55 ×1010^-3 m³/mol

Heat of vaporization

n/a kJ/mol

Heat of fusion

62 kJ/mol

Vapor pressure

unknown Pa at 1323 K

Velocity of sound

unknown m/s at 293.15 K

Miscellaneous

Electronegativity

1.1 (Pauling scale)

Specific heat capacity

unknown J/(kg*K)

Electrical conductivity

unknown 10⁶/m ohm

Thermal conductivity

12 W/(m*K)

1^st ionization potential

499 kJ/mol

2^nd ionization potential

1170 kJ/mol

3^rd ionization potential

unknown kJ/mol

4^th ionization potential

unknown kJ/mol

Most Stable Isotopes

iso	NA	half-life	DM	DE M eV	DP
²²⁵Ac	{syn.}	10 days	α	5.935	²²¹Fr
²²⁶Ac	{syn.}	29.37 hours	β^-	1.117	²²⁶Th
²²⁶Ac	{syn.}	29.37 hours	e capture	0.640	²²⁶Ra
²²⁶Ac	{syn.}	29.37 hours	α	5.536	²²²Fr
²²⁷Ac	100 %	21.773 years	β^-	0.045	²²⁷Th
²²⁷Ac	100 %	21.773 years	α	5.042	²²³Fr

SI units & STP are used except where noted.

Actinium is a chemical element in the periodic table that has the symbol Ac and atomic number 89.

Table of contents

1 Notable Characteristics
2 Applications
3 History
4 Occurrence
5 Compounds
6 Isotopes
7 Precautions
8 External Links

Notable Characteristics

Actinium is a silvery radioactive metallic element. Actinium glows in the dark due to its intense radioactivity with an eerie blue light. It is found only in traces in uranium ores as 227-Ac, an &alpha and β emitter with a half-life of 21.773 years. One ton of uranium ore contains about a tenth of a gram of actinium.

Applications

It is about 150 times as radioactive as radium, making it valuable as a neutron source. Otherwise it has no significant industrial applications.

Actinium-225 is used in medicine to produce Bi-213 in a reusable generator or can be used alone as an agent for radio-immunotherapy.

Actinium was discovered in 1899 by Andr�-Louis Debierne, a French chemist, who separated it from pitchblende. Friedrich Otto Giesel independently discovered actinium in 1902. The chemical behavior of actinium is similar to that of the rare earth lanthanum.

The word actinium comes from the Greek aktis, aktinos, meaning beam or ray.

Occurrence

Actinium is found in trace amounts in uranium ore, but more commonly is made in milligram amounts by the neutron irradiation of 226-Ra in a nuclear reactor. Actinium metal has been prepared by the reduction of actinium fluoride with lithium vapor at about 1100 to 1300-degrees C.

Compounds

Isotopes

Naturally occurring actinium is composed of 1 radioactive isotope; with 227-Ac being the most abundant (100% natural abundance). 27 radioisotopes have been characterized with the most stable being 227-Ac with a half-life of 21.773 years, 225-Ac with a half-life of 10 days, and 226-Ac with a half-life of 29.37 hours. All of the remaining radioactive isotopes have half-lifes that are less than 10 hours and the majority of these have half lifes that are less than 1 minute. This element also has 2 meta states.

Purified actinium-227 comes into equilibrium with its decay products at the end of 185 days, and then decays according to its 21.773-year half-life.

The isotopes of actinium range in atomic weight from 206 amu (206-actinium) to 234 amu (234-actinium).

Precautions

Actinium-227 is extremely radioactive, and in terms of its potential for radiation induced health effects, actinium-227 is about as dangerous as plutonium. Ingesting even small amounts of actinium-227 would represent a serious health hazard.