1. atomic number 86 a radioactive gaseous element formed by the disintegration of radium; the heaviest of the inert gasses; occurs naturally (especially in areas over granite) and is considered a hazard to health
  2. atomic number 16 an abundant tasteless odorless multivalent nonmetallic element; best known in yellow crystals; occurs in many sulphide and sulphate minerals and even in native form (especially in volcanic regions)
  3. atomic number 76 a hard brittle blue-grey or blue-black metallic element that is one of the platinum metals; the heaviest metal known
  4. atomic number 88 an intensely radioactive metallic element that occurs in minute amounts in uranium ores
  5. atomic number 96 a radioactive transuranic metallic element
  6. atomic number 66 a trivalent metallic element of the rare earth group
  7. atomic number 87 a radioactive element of the alkali-metal group discovered as a disintegration product of actinium
  8. atomic number 89 a radioactive element of the actinide series
  9. atomic number 36 a colorless element that is one of the six inert gasses
  10. atomic number 83 a heavy brittle diamagnetic trivalent metallic element
  11. atomic number 26 a heavy ductile magnetic metallic element
  12. atomic number 82 a soft heavy toxic malleable metallic element
  13. atomic number 84 a radioactive metallic element that is similar to tellurium and bismuth; occurs in uranium ores but can be produced by bombarding bismuth with neutrons in a nuclear reactor
  14. atomic number 85 a highly unstable radioactive element
  15. atomic number 46 a silver-white metallic element of the platinum group that resembles platinum; occurs in some copper and nickel ores; does not tarnish at ordinary temperatures and is used (alloyed with gold) in jewelry
  16. atomic number 56 a soft silvery metallic element of the alkali earth group
  17. atomic number 68 a trivalent metallic element of the rare earth group
  18. atomic number 80 a heavy silvery toxic univalent and bivalent metallic element; the only metal that is liquid at ordinary temperatures
  19. atomic number 81 a soft grey malleable metallic element that resembles tin but discolors on exposure to air; it is highly toxic and is used in rodent and insect poisons; occurs in zinc blende and some iron ores
  20. atomic number 6 an abundant nonmetallic tetravalent element occurring in three allotropic forms: amorphous carbon and graphite and diamond; occurs in all organic compounds

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