1. atomic number 68 a trivalent metallic element of the rare earth group
  2. atomic number 58 a ductile grey metallic element of the lanthanide series
  3. atomic number 78 a heavy precious metallic element
  4. atomic number 88 an intensely radioactive metallic element that occurs in minute amounts in uranium ores
  5. atomic number 18 a colorless and odorless inert gas
  6. atomic number 66 a trivalent metallic element of the rare earth group
  7. atomic number 67 a trivalent metallic element of the rare earth group
  8. atomic number 61 a soft silvery metallic element of the rare earth group having no stable isotope; was discovered in radioactive form as a fission product of uranium
  9. atomic number 64 a ductile silvery-white ductile ferromagnetic trivalent metallic element of the rare earth group
  10. atomic number 28 a hard malleable ductile silvery metallic element that is resistant to corrosion; used in alloys; occurs in pentlandite and smaltite and garnierite and millerite
  11. atomic number 38 a soft silver-white or yellowish metallic element of the alkali metal group; turns yellow in air; occurs in celestite and strontianite
  12. atomic number 48 a soft bluish-white ductile malleable toxic bivalent metallic element; occurs in association with zinc ores
  13. atomic number 60 a yellow trivalent metallic element of the rare earth group
  14. atomic number 62 a grey lustrous metallic element of the rare earth group
  15. atomic number 63 a bivalent and trivalent metallic element of the rare earth group
  16. atomic number 65 a metallic element of the rare earth group
  17. atomic number 69 a soft silvery metallic element of the rare earth group
  18. 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
  19. atomic number 98 a radioactive transuranic element
  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