Replies to This Discussion

Permalink Reply by Michel on February 13, 2013 at 11:03am

Americium?!?

Permalink Reply by Adriana on February 13, 2013 at 12:11pm

Americium

From Wikipedia, the free encyclopedia

silvery white
General properties
Name, symbol,number	americium, Am, 95
Pronunciation	/ˌæməˈrɪsiəm/ am-ə-ris-ee-əm
Metallic category	actinide
Group, period,block	n/a, 7, f
Standard atomic weight	(243)
Electron configuration	[Rn] 5f7 7s2 2, 8, 18, 32, 25, 8, 2
History
Discovery	Glenn T. Seaborg, Ralph A. James, Leon O. Morgan, Albert Ghiorso (1944)
Physical properties
Phase	solid
Density (nearr.t.)	12 g·cm−3
Melting point	1449 K, 1176 °C, 2149 °F
Boiling point	2880 K, 2607 °C, 4725 °F
Heat of fusion	14.39 kJ·mol−1
Molar heat capacity	62.7 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1239 1356
Atomic properties
Oxidation states	7, 6, 5, 4, 3, 2 (amphoteric oxide)
Electronegativity	1.3 (Pauling scale)
Ionization energies	1st: 578 kJ·mol−1
Atomic radius	173 pm
Covalent radius	180±6 pm
Miscellanea
Crystal structure	hexagonal
Magnetic ordering	paramagnetic
Electrical resistivity	0.69[1] µΩ·m
Thermal conductivity	10 W·m−1·K−1
CAS registry number	7440-35-9
Most stable isotopes
Main article: Isotopes of americium
iso NA half-life DM DE (MeV) DP 241Am trace 432.2 y SF - - α 5.486 237Np 242mAm trace 141 y IT 0.049 242Am α 5.637 238Np SF - - 243Am trace 7370 y SF - - α 5.275 239Np
v   t   e   · r

Americium (pron.: /ˌæməˈrɪsiəm/ am-ə-ris-ee-əm) is a transuranic radioactive chemical element that has the symbol Am and atomic number 95. This transuranic element of theactinide series is located in the periodic table below the lanthanide element europium, and thus by analogy was named after another continent, America.^[2]

Americium was first produced in 1944 by the group of Glenn T. Seaborg at the University of California, Berkeley. Although it is the third element in the transuranic series, it was discovered fourth, after the heavier curium. The discovery was kept secret and only released to the public in November 1945. Most americium is produced by bombarding uranium orplutonium with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains about 100 grams of americium. It is widely used in commercial ionization chamber smoke detectors, as well as in neutron sources and industrial gauges. Several unusual applications, such as a nuclear battery or fuel for space ships with nuclear propulsion, have been proposed for the isotope ^242mAm, but they are as yet hindered by the scarcity and high price of this nuclear isomer.

Permalink Reply by Adriana on February 13, 2013 at 12:10pm

This is GREAT!!!!

Permalink Reply by Onyango Makagutu on February 14, 2013 at 5:41am

This is great! Some of these elements didn't feature in my chemistry lessons, maybe my teacher didn't know about them, a good teacher though he was

Permalink Reply by Neal on February 14, 2013 at 8:33am

I'm really liking this. =)