Chemistry Learner

It's all about Chemistry

Americium

What is Americium

Americium (pronunciation: am-er-ISH-ee-em) is a shiny, silvery, synthetic element belonging to the actinide series and is represented by the chemical symbol Am [1, 2, 3]. Since it is artificially created, it does not have any known stable isotopes [4]. However, it has nineteen radioisotopes, out of which the most stable are 243Am and 241Am characterized by a half-life period of 7,370 years and 432.2 years respectively [4].

Americium Symbol

Where is Americium Found

It is naturally found in trace quantities in uranium mineral ores [1]. The element is commercially produced by bombarding plutonium with neutrons in nuclear reactors [1]. It is also produced during the explosion of nuclear weapons [1].

History

Origin of its Name: The element is named after America, the country where it was discovered [1].

Who discovered it: The American chemist Glenn Theodore Seaborg, as well as his colleagues Ralph James, Albert Ghiorso, and Leon Morgan,  are credited for the discovery of americium [1].

When and How was it Discovered

In 1944, Glenn Seaborg along with his team of researchers while working at the University of Chicago’s Wartime Metallurgical Laboratory produced this transuranium element through the bombardment of plutonium-239 by neutrons to produce plutonium-240, which was again bombarded to produce plutonium-241 [1, 3]. The plutonium-241 underwent radioactive decay to form americium-241 [3]. The discovery was announced by Seaborg in late 1945 [3].

Americium

Americium Identification

Atomic number 95 [1]
CAS number 7440-35-9 [1]
Position in the periodic table Group Period Block
  Actinides [1] 7 [1] f [1]

Location of Americium in the Periodic Table

Properties and Characteristics of Americium

General Properties

Relative atomic mass 243 [1]
Atomic mass 243 amu [1]
Molar mass 243.061 g/mol [5, 6]

Physical Properties

Color Silvery-white [1, 7]
Melting point/freezing point 1176 °C, 2149 °F [1]
Boiling point 2011 °C, 3652 °F [1]
Density 12 g cm-3 [1]
State of matter at room temperature (solid/liquid/gas) Solid [1, 7]
Hardness
– Brinell Unknown [8]
– Mohs Unknown [8]
– Vickers Unknown [8]
Electrical Conductivity Unknown [8]
Thermal (heat) conductivity 10 W/(m K) [8]
Specific heat Unknown [1]
Bulk modulus Unknown [1]
Shear modulus Unknown [1]
Young’s modulus Unknown [1]
Vapor pressure
– Temperature (K) 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
– Pressure (Pa) 3.88X 10-7 1.67X 10-3 0.423 21.35

Chemical Properties

Oxidation states 6, 5, 4, 3 [1]
Isotopes Isotope Mass Abundance (%) Half-life Mode of decay
  241Am 241.057 432.7 y α
  1.2 X 1014 y sf
  243Am 243.061 7.37 X 103 y α
  2 X 1014 y sf

Atomic Data of Americium (Element 95)

Valence electrons 2 [9]
Quantum numbers
– n 5 [9]
– ℓ 3 [9]
– m 3 [9]
– ms +1/2 [9]
Electron configuration (noble gas configuration) [Rn] 5f77s2 [1]
Atomic structure
– Number of electrons 95 [6]
– Number of neutrons 148 [6]
– Number of protons 95 [6]
Radius of Atom
– Atomic radius 2.44 Å [1]
– Covalent radius 1.73 Å [1]
Electronegativity (Pauling-scale) Unknown [1]
Electron affinity Unknown [1]
Ionization energy (kJ mol-1) 1st 2nd 3rd 4th 5th 6th 7th 8th
  576.384

Americium Electron Configuration (Bohr Model)

What is It Used for

  • Small amounts of americium dioxide are used in smoke detectors and alarms [1, 6].
  • Several isotopes of americium are now investigated on their use as a possible power source for deep space vehicles [1, 3]. It could potentially become the favored fuel source and replace the commonly used plutonium [3].
  • As a portable source of alpha and gamma rays, it has plenty of industrial and medical applications like spectroscopy and radiography [3].

Americium Smoke Detector

Toxicity of Americium

Americium is known to be toxic because of its radioactivity and exposure to this radiation can cause genetic changes in human cells, resulting in bone cancers [10]. High levels of radiation from americium can damage the lungs, liver, thyroid, and kidneys [10].

Interesting Facts

  • The element is represented with a smoke alarm-shaped object painted with the colors of the American flag, indicating the place of its origin [1].
  • At room temperature, it discolors slowly in dry air [6].

Cost of Americium

The price of pure americium is $1,500 per gram [6].

References

  1. http://www.rsc.org/periodic-table/element/95/americium
  2. https://education.jlab.org/itselemental/ele095.html
  3. https://www.livescience.com/39874-facts-about-americium.html
  4. https://education.jlab.org/itselemental/iso095.html
  5. https://pubchem.ncbi.nlm.nih.gov/compound/105139#section=Top
  6. https://www.convertunits.com/molarmass/Americium
  7. https://www.chemicool.com/elements/americium.html
  8. http://periodictable.com/Elements/095/data.html
  9. http://chemistry-reference.com/q_elements.asp?language=en&Symbol=Am
  10. https://www.atsdr.cdc.gov/phs/phs.asp?id=809&tid=158

Leave a Reply

Your email address will not be published. Required fields are marked *

Trending Topics