1. atomic number 21 a white trivalent metallic element
  2. atomic number 11 a silvery soft waxy metallic element of the alkali metal group; occurs abundantly in natural compounds (especially in salt water); burns with a yellow flame and reacts violently in water; occurs in sea water and in the mineral halite (rock salt)
  3. atomic number 29 a ductile malleable reddish-brown corrosion-resistant diamagnetic metallic element; occurs in various minerals but is the only metal that occurs abundantly in large masses; used as an electrical and thermal conductor
  4. atomic number 25 a hard brittle grey polyvalent metallic element that resembles iron but is not magnetic; used in making steel; occurs in many minerals
  5. atomic number 12 a light silver-white ductile bivalent metallic element
  6. atomic number 22 a light strong grey lustrous corrosion-resistant metallic element used in strong lightweight alloys (as for airplane parts); the main sources are rutile and ilmenite
  7. atomic number 27 a hard ferromagnetic silver-white bivalent or trivalent metallic element; a trace element in plant and animal nutrition
  8. atomic number 24 a hard brittle multivalent metallic element
  9. atomic number 26 a heavy ductile magnetic metallic element
  10. atomic number 41 a soft grey ductile metallic element used in alloys
  11. 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
  12. atomic number 20 a white metallic element that burns with a brilliant light
  13. atomic number 23 a soft silvery white toxic metallic element used in steel alloys; it occurs in several complex minerals including carnotite and vanadinite
  14. 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
  15. atomic number 31 a rare silvery metallic element
  16. atomic number 51 a metallic element having four allotropic forms
  17. atomic number 71 a trivalent metallic element of the rare earth group
  18. 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
  19. atomic number 91 a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead
  20. atomic number 1 a nonmetallic univalent element that is normally a colorless and odorless highly flammable diatomic gas; the simplest and lightest and most abundant element in the universe