What do nuclear disasters and smoke detectors share in common?
This week's element is americium, which has the atomic symbol *Am* and the atomic number, *95*. This element was named for the continent, America, and its name was inspired by the lanthanoid, europium, which resides directly above it on the periodic table and shares many of the same chemical properties.
Americium is a transuranic element, which means that it has an atomic number greater than 92. (All transuranic elements are are radioactive and unstable.) As you can see in the above image, americium is a shiny silvery-coloured metal. Trace amounts of several americium isotopes can be found in the wild in minerals containing uranium and small amounts can be found in areas where nuclear weapons tests or disasters occurred.
Americium has 19 isotopes. Or so. Two isotopes, which decay by emitting alpha particles, have have relatively long half-lives; americium-243 has a half-life of 7,370 years and americium-241 has a half-life of 432.2 years. The other isotopes have fleeting half-lives, none of which exceeds 51 hours. (Keep in mind that americium's many daughters emit gamma-rays and neutrons, which are very damaging.) Americium isotopes with odd numbers of neutrons are most unstable, having both a high rate of nuclear fission and a low critical mass.
Due to its radioactivity and instability, americium is dangerous and thus, is only handled in nuclear facilities and research laboratories under stringent precautions. Despite the fact that it can be lethal, americium has saved uncounted lives around the world. How? Americium dioxide is the "active ingredient" in home smoke detectors.
One type of smoke detector -- the one found in most private homes -- uses a very small "button" of americium-241 to detect smoke or other particulates in the air. (This amount of americium is too small to cause harm to the home's occupants.) Basically, americium-241 emits alpha particles that ionize air molecules that circulate freely through a small chamber inside the device. These ions carry a small electrical current between two electrodes that are also located in the chamber. When smoke enters this chamber, it absorbs the ions, which then causes the current to drop. This change in electrical current activates the alarm.
Of course, other particulates (such as steam or dust) can also set off the alarm, falsely. I rediscovered this annoying "feature" during my recent stay in London whilst showering in a bathroom that was the size of a postage stamp. I opened the bathroom door so I could use the mirror, and the increase in humidity in the room set off the smoke detector.
Here's a brilliant video that explains in detail the engineering of americium-based smoke detectors:
[Video link]
Because americium must be synthesised, it is considered to be an artificial element. For this reason, it is of little interest to biologists because it is not essential for life. However, several bacterial and fungal species do bind americium and remove it from aqueous solution, making them promising for removing americium from contaminated waterways.
Here's some of our favourite chemists telling us a little more about the wonders of americium:
[Video link]
.. .. .. .. .. .. .. .. .. .. .. ..
Video journalist Brady Haran is the man with the camera and the University of Nottingham is the place with the chemists. You can follow Brady on twitter @periodicvideos and the University of Nottingham on twitter @UniofNottingham
*You've already met these elements:*
Plutonium: *Pu*, atomic number *94*
Neptunium: *Np*, atomic number *93*
Uranium: *U*, atomic number *92*
Protactinium: *Pa*, atomic number *91*
Thorium: *Th*, atomic number *90*
Actinium: *Ac*, atomic number *89*
Radium: *Ra*, atomic number *88*
Francium: *Fr*, atomic number *87*
Radon: *Rn*, atomic number *86*
Astatine: *As*, atomic number *85*
Polonium: *Po*, atomic number *84*
Bismuth: *Bi*, atomic number *83*
Lead: *Pb*, atomic number *82*
Thallium: *Tl*, atomic number *81*
Mercury: *Hg*, atomic number *80*
Gold: *Au*, atomic number *79*
Platinum: *Pt*, atomic number *78*
Iridium: *Ir*, atomic number *77*
Osmium: *Os*, atomic number *76*
Rhenium: *Re*, atomic number *75*
Tungsten: *W*, atomic number *74*
Tantalum: *Ta*, atomic number *73*
Hafnium: *Hf*, atomic number *72*
Lutetium: *Lu*, atomic number *71*
Ytterbium: *Yb*, atomic number *70*
Thulium: *Tm*, atomic number *69*
Erbium: *Er*, atomic number *68*
Holmium: *Ho*, atomic number *67*
Dysprosium: *Dy*, atomic number *66*
Terbium: *Tb*, atomic number *65*
Gadolinium: *Gd*, atomic number *64*
Europium: *Eu*, atomic number *63*
Samarium: *Sm*, atomic number *62*
Promethium: *Pm*, atomic number *61*
Neodymium: *Nd*, atomic number *60*
Praseodymium: *Pr*, atomic number *59*
Cerium: *Ce*, atomic number *58*
Lanthanum: *La*, atomic number *57*
Barium: *Ba*, atomic number *56*
Cæsium: *Cs*, atomic number *55*
Xenon: *Xe*, atomic number *54*
Iodine: *I*, atomic number *53*
Tellurium: *Te*, atomic number *52*
Antimony: *Sb*, atomic number *51*
Tin: *Sn*, atomic number *50*
Indium: *In*, atomic number *49*
Cadmium: *Cd*, atomic number *48*
Silver: *Ag*, atomic number *47*
Palladium: *Pd*, atomic number *46*
Rhodium: *Rh*, atomic number *45*
Ruthenium: *Ru*, atomic number *44*
Technetium: *Tc*, atomic number *43*
Molybdenum: *Mo*, atomic number *42*
Niobium: *Ni*, atomic number *41*
Zirconium: *Zr*, atomic number *40*
Yttrium: *Y*, atomic number *39*
Strontium: *Sr*, atomic number *38*
Rubidium: *Rr*, atomic number *37*
Krypton: *Kr*, atomic number *36*
Bromine: *Br*, atomic number *35*
Selenium: *Se*, atomic number *34*
Arsenic: *As*, atomic number *33*
Germanium: *Ge*, atomic number *32*
Gallium: *Ga*, atomic number *31*
Zinc: *Zn*, atomic number *30*
Copper: *Cu*, atomic number *29*
Nickel: *Ni*, atomic number *28*
Cobalt: *Co*, atomic number *27*
Iron:* Fe*, atomic number *26*
Manganese: *Mn*, atomic number *25*
Chromium: *Cr*, atomic number *24*
Vanadium: *V*, atomic number *23*
Titanium: *Ti*, atomic number *22*
Scandium: *Sc*, atomic number *21*
Calcium: *Ca*, atomic number *20*
Potassium: *K*, atomic number *19*
Argon: *Ar*, atomic number *18*
Chlorine: *Cl*, atomic number *17*
Sulfur: *S*, atomic number *16*
Phosphorus: *P*, atomic number *15*
Silicon: *Si*, atomic number *14*
Aluminium: *Al*, atomic number *13*
Magnesium: *Mg*, atomic number *12*
Sodium: *Na*, atomic number *11*
Neon: *Ne*, atomic number *10*
Fluorine: *F*, atomic number *9*
Oxygen: *O*, atomic number *8*
Nitrogen: *N*, atomic number *7*
Carbon: *C*, atomic number *6*
Boron: *B*, atomic number *5*
Beryllium: *Be*, atomic number *4*
Lithium: *Li*, atomic number *3*
Helium: *He*, atomic number *2*
Hydrogen: *H*, atomic number *1*
Here's the Royal Society of Chemistry's interactive Periodic Table of the Elements that is just really really fun to play with!
.. .. .. .. .. .. .. .. .. .. ..
Grrlscientist can also be found here: Maniraptora, and she lurks on social media: facebook, Google +, LinkedIn, Pinterest and of course, twitter: @GrrlScientist Reported by guardian.co.uk 2 hours ago.
This week's element is americium, which has the atomic symbol *Am* and the atomic number, *95*. This element was named for the continent, America, and its name was inspired by the lanthanoid, europium, which resides directly above it on the periodic table and shares many of the same chemical properties.
Americium is a transuranic element, which means that it has an atomic number greater than 92. (All transuranic elements are are radioactive and unstable.) As you can see in the above image, americium is a shiny silvery-coloured metal. Trace amounts of several americium isotopes can be found in the wild in minerals containing uranium and small amounts can be found in areas where nuclear weapons tests or disasters occurred.
Americium has 19 isotopes. Or so. Two isotopes, which decay by emitting alpha particles, have have relatively long half-lives; americium-243 has a half-life of 7,370 years and americium-241 has a half-life of 432.2 years. The other isotopes have fleeting half-lives, none of which exceeds 51 hours. (Keep in mind that americium's many daughters emit gamma-rays and neutrons, which are very damaging.) Americium isotopes with odd numbers of neutrons are most unstable, having both a high rate of nuclear fission and a low critical mass.
Due to its radioactivity and instability, americium is dangerous and thus, is only handled in nuclear facilities and research laboratories under stringent precautions. Despite the fact that it can be lethal, americium has saved uncounted lives around the world. How? Americium dioxide is the "active ingredient" in home smoke detectors.
One type of smoke detector -- the one found in most private homes -- uses a very small "button" of americium-241 to detect smoke or other particulates in the air. (This amount of americium is too small to cause harm to the home's occupants.) Basically, americium-241 emits alpha particles that ionize air molecules that circulate freely through a small chamber inside the device. These ions carry a small electrical current between two electrodes that are also located in the chamber. When smoke enters this chamber, it absorbs the ions, which then causes the current to drop. This change in electrical current activates the alarm.
Of course, other particulates (such as steam or dust) can also set off the alarm, falsely. I rediscovered this annoying "feature" during my recent stay in London whilst showering in a bathroom that was the size of a postage stamp. I opened the bathroom door so I could use the mirror, and the increase in humidity in the room set off the smoke detector.
Here's a brilliant video that explains in detail the engineering of americium-based smoke detectors:
[Video link]
Because americium must be synthesised, it is considered to be an artificial element. For this reason, it is of little interest to biologists because it is not essential for life. However, several bacterial and fungal species do bind americium and remove it from aqueous solution, making them promising for removing americium from contaminated waterways.
Here's some of our favourite chemists telling us a little more about the wonders of americium:
[Video link]
.. .. .. .. .. .. .. .. .. .. .. ..
Video journalist Brady Haran is the man with the camera and the University of Nottingham is the place with the chemists. You can follow Brady on twitter @periodicvideos and the University of Nottingham on twitter @UniofNottingham
*You've already met these elements:*
Plutonium: *Pu*, atomic number *94*
Neptunium: *Np*, atomic number *93*
Uranium: *U*, atomic number *92*
Protactinium: *Pa*, atomic number *91*
Thorium: *Th*, atomic number *90*
Actinium: *Ac*, atomic number *89*
Radium: *Ra*, atomic number *88*
Francium: *Fr*, atomic number *87*
Radon: *Rn*, atomic number *86*
Astatine: *As*, atomic number *85*
Polonium: *Po*, atomic number *84*
Bismuth: *Bi*, atomic number *83*
Lead: *Pb*, atomic number *82*
Thallium: *Tl*, atomic number *81*
Mercury: *Hg*, atomic number *80*
Gold: *Au*, atomic number *79*
Platinum: *Pt*, atomic number *78*
Iridium: *Ir*, atomic number *77*
Osmium: *Os*, atomic number *76*
Rhenium: *Re*, atomic number *75*
Tungsten: *W*, atomic number *74*
Tantalum: *Ta*, atomic number *73*
Hafnium: *Hf*, atomic number *72*
Lutetium: *Lu*, atomic number *71*
Ytterbium: *Yb*, atomic number *70*
Thulium: *Tm*, atomic number *69*
Erbium: *Er*, atomic number *68*
Holmium: *Ho*, atomic number *67*
Dysprosium: *Dy*, atomic number *66*
Terbium: *Tb*, atomic number *65*
Gadolinium: *Gd*, atomic number *64*
Europium: *Eu*, atomic number *63*
Samarium: *Sm*, atomic number *62*
Promethium: *Pm*, atomic number *61*
Neodymium: *Nd*, atomic number *60*
Praseodymium: *Pr*, atomic number *59*
Cerium: *Ce*, atomic number *58*
Lanthanum: *La*, atomic number *57*
Barium: *Ba*, atomic number *56*
Cæsium: *Cs*, atomic number *55*
Xenon: *Xe*, atomic number *54*
Iodine: *I*, atomic number *53*
Tellurium: *Te*, atomic number *52*
Antimony: *Sb*, atomic number *51*
Tin: *Sn*, atomic number *50*
Indium: *In*, atomic number *49*
Cadmium: *Cd*, atomic number *48*
Silver: *Ag*, atomic number *47*
Palladium: *Pd*, atomic number *46*
Rhodium: *Rh*, atomic number *45*
Ruthenium: *Ru*, atomic number *44*
Technetium: *Tc*, atomic number *43*
Molybdenum: *Mo*, atomic number *42*
Niobium: *Ni*, atomic number *41*
Zirconium: *Zr*, atomic number *40*
Yttrium: *Y*, atomic number *39*
Strontium: *Sr*, atomic number *38*
Rubidium: *Rr*, atomic number *37*
Krypton: *Kr*, atomic number *36*
Bromine: *Br*, atomic number *35*
Selenium: *Se*, atomic number *34*
Arsenic: *As*, atomic number *33*
Germanium: *Ge*, atomic number *32*
Gallium: *Ga*, atomic number *31*
Zinc: *Zn*, atomic number *30*
Copper: *Cu*, atomic number *29*
Nickel: *Ni*, atomic number *28*
Cobalt: *Co*, atomic number *27*
Iron:* Fe*, atomic number *26*
Manganese: *Mn*, atomic number *25*
Chromium: *Cr*, atomic number *24*
Vanadium: *V*, atomic number *23*
Titanium: *Ti*, atomic number *22*
Scandium: *Sc*, atomic number *21*
Calcium: *Ca*, atomic number *20*
Potassium: *K*, atomic number *19*
Argon: *Ar*, atomic number *18*
Chlorine: *Cl*, atomic number *17*
Sulfur: *S*, atomic number *16*
Phosphorus: *P*, atomic number *15*
Silicon: *Si*, atomic number *14*
Aluminium: *Al*, atomic number *13*
Magnesium: *Mg*, atomic number *12*
Sodium: *Na*, atomic number *11*
Neon: *Ne*, atomic number *10*
Fluorine: *F*, atomic number *9*
Oxygen: *O*, atomic number *8*
Nitrogen: *N*, atomic number *7*
Carbon: *C*, atomic number *6*
Boron: *B*, atomic number *5*
Beryllium: *Be*, atomic number *4*
Lithium: *Li*, atomic number *3*
Helium: *He*, atomic number *2*
Hydrogen: *H*, atomic number *1*
Here's the Royal Society of Chemistry's interactive Periodic Table of the Elements that is just really really fun to play with!
.. .. .. .. .. .. .. .. .. .. ..
Grrlscientist can also be found here: Maniraptora, and she lurks on social media: facebook, Google +, LinkedIn, Pinterest and of course, twitter: @GrrlScientist Reported by guardian.co.uk 2 hours ago.