What is  H925 B207? (Radioactive Element) and where to find it and how dangerous it is?
338944
You must be asking about mercury sulfide, HgS2, which is red.  It is quite dangerous.  If you do not use proper respiratory protection, wash thoroughly, and keep it out of the environment, you will get mercury poisioning by working with it.  You probably need a license to buy it.
770649
94,240Pu ---> 40,93Zr + 54,144Xe + _3_ 0,1n\n\nThe first number is the proton number, the second is the nucleon number. Both of these must be conserved in fission. As the number of protons is already conserved, the difference in the nucleon number must come from free neutrons.
213411
Atomic Number 3\nhttp://www.jergym.hiedu.cz/~canovm/vyhledav/varianty/litva.gif
190550
It is not against the laws of physics to create element 119 and there is no cut off number on the periodic table.  Elements aren't included until their existance has been established.  In principle you could have element number 158,982.  In fact, if you like you can think of neutron stars as being really big atoms.  The problem is that as the element number (the number of protons) increases, the attractive nuclear force binding the nucleus together can't overcome the repulsive electric force between the protons.  This is why large elements tend to be radioactive.  You may have noticed that large numbered elements tend to have many more neutrons than protons.  The extra neutrons help keep the larger elements together by creating a stronger nuclear force.  You may think that by adding more neutrons we could make any larger element stable by making the nuclear force stronger, however more neutrons in the nucleus means a greater chance of quantum tunneling (leading to radioactive decay).
1068949
a mixture of barium-133 and cesium-137\n\nhttp://www.orau.org/ptp/collection/nuclearmedicine/mockiodinekit.htm
7018
58.93\nJust go to your Yahoo search page and type in 'Periodic Table'
887068
Element 118 may have been found about two weeks ago:\n\nhttp://www.fogcityjournal.com/news_in_brief/bcn_livermore_labs_element_118_061016.shtml
451632
Uranium is a chemical element in the periodic table that has the symbol U and atomic number 92. Heavy, silvery-white, toxic, metallic, naturally radioactive, pyrophoric, and teratogenic, uranium belongs to the actinide series and its isotope 235U is used as the fuel for nuclear reactors and the explosive material for nuclear weapons. Depleted uranium is used in incendiary projectile weapons. Uranium is commonly found in very small amounts in rocks, soil, water, plants, and animals (including humans).
9075
"The transuranium elements are so called because they all lie beyond uranium; that is to say, they are elements with atomic numbers higher than 92 in the periodic table."\nThat's from the web site listed below.\nSo find a periodic chart, and look at all the elements above At. No. 92.
773500
Pu 239 is mostly manmade. It is highly toxic and its half-life is 24,000 years.\nExposure to the reaction of a critical mass is not so good either.
668658
Rarest substance on earth are nuclei of sertain elements that are artificially made by physicists and sre very shortlived and known by just a few nuclei. It can be the element with atomic number 111 through 118. Visit\nhttp://periodic.lanl.gov/default.htm
943337
Boring Stuff:\nAtomic weight: 9.012\nMelting point 1278 degrees Celsius\nBoiling oint 2970 degrees C\nDensity 1.8 kg/L\nHas no stable isotopes.\nSoluble in all acids except nitric acid.\n\nIs the 47th most abundant elemnt and considered a rare metal.\n\n\nMedical Stuff:\nIf beryllium dust is breatehd in, they cause chronic inflamation of the lungs and shortge of breath. Brief exposure to beryllium is caused berylliosis. \nIt's carcinogenic.\n\nWar History:\nBeryllium does not absorb nuetrons and reflects some of them, and it's used in nuclear weapons and in teh nuclear energy industry. \n\nEconomic.&#92;:\nWehn copper and nickel are laloyed with Be, they become much better at conducting electricity. \nBeryllium is trasnparent ot Xrays, which is why it is used in windows for Xray Tubes.
854963
Check out this website it will tell you all you would ever want to know about radon and any other element.\n\nhttp://www.lenntech.com/Periodic-chart-elements/Rn-en.htm
964537
Tritium.\n\nThat is the isotope of hydrogen with one proton and two neutron in the nucleus.  It is used as a low grade radio-active activator in phosphorescent paint, replacing radium which is much more dangerous.\n\n(Science Teacher below is wrong: deuterium is a stable nucleon, it is thus not radio active)
1116812
The paper cited below says "It is the rarest element with an amount of only 550 g. in the entire earth's crust,"\n\nThat's a little more than 18 atoms.
701573
a radioactive element is unstable because it has too many neutrons in its nucleus.
554348
goldwing doesn't know what he's taking about... Heavy water, which is distiguished by the presence of H-2, or Deuterium, is _not_ radioactive.  It is a stable isotope that does exist naturally (.015% from the table of nuclides), stable nuclei don't emit radioactive particles, radioactive particles are emitted as a means for an unstable nuclei to return to a stable form. The reason it is licensed is because heavy water can harm biogical systems, but not because of radiocativity, but rather because biological systems are quite sensitive to the solvent properties of water (which change when deuterium is substituted for natural hydrogen), given a human would have to drink pure heavy water for over two weeks before he/she became seriously ill, but it's a risk nonetheless.  Another reason that it is licensed for production is because a facility capable of seperating an isotope like H2 from natural hydrogen could potentially seperate another fissile isotope (U-235) from natural Uranium...