Science / Periodic Table of Elements / Americium (Am): Atomic number: 95, Atomic mass: (243) g.mol -1, Electronegativity: unknown, Density: 13.67 g.cm-3 at 20°C, Melting point: 994 °C, Boiling point: 2607 °C, Vanderwaals radius: unknown, Ionic radius: unknown, Isotopes: 8, Electronic shell: [ Rn ] 5f7 7s2, Energy of first ionisation: 578 kJ.mol -1, Discovered by: G.T. Seaborg in 1945. Americium is a silvery-white synthetic metal. It slowly tarnishes in dry air, but it is resistent to alkalis. It is denser than lead. Several americium compounds have been made and these are generally coloured - for example, the chloride is pink. Applications: Americium has some uses: it is used in some smoke detectors, as portable gamma ray source in radiography, to help to create flat glass. However this isotope is extremely expensive to produce in usable quantities. Americium in the environment: Americium probably does occur naturally on Earth, but only in incredibly tiny amounts in uranium minerals where nuclear reactions may occasionally produce an atom. There are no natural sources of americium, but it is likely to have been present at times in the past when local concentrations of uranium where sufficient to cause nuclear reactions. Americium can be added during accidental release in nuclear production plants. Americium, as the isotope americium-243, is produced in kilogram quantities from plutonim-239.
Technology / Home Audio / Amplitude Modulation (AM): In radio broadcasting, amethod of modulation in which the amplitude of the carrier voltage is varied in proportion to the changing frequency value of an applied (audio) voltage. MORE