Down 1. This member of Group i3 melts at only 30C 2. This nonmetal forms ionic, metallic, and covalent compounds 3. The 2+ ion of this rare earth metal has a half-filled set of forbitals 4.The"Tyrannosaurus rex"of the elements. 5. Its compounds were once used to produce glow-in-the-dark watches 6. This rare earth element was very difficult to separate from its neighbor, praseodymiu 7. Named after the"father"of the periodic table 8. The bottom member of Group 2, alphabetically 9. An organometallic compound of this main group metal is used in the preservation of books 10. The only metal to commonly form a diatomic cation in solution 11. This metal forms a magnetic oxide of formula M3O4 12. This gaseous element was once known as"dephlogisticated air 13. One allotrope is stored under water 14. Its hexaaqua ion in the +2 oxidation state is pink 15. This actinoid is usually sold as a compound known as"yellow cake 16. Xerography would be impossible without this element 17. Its common oxyanion has a characteristic purple color 18. The densest non-radioactive metal of Group 9 19. The highest atomic number element for which stable isotopes are known 20. The only liquid nonmetal at SATP 21. Its carbonate is one of the common minerals on the surface of the earth 22. The least electronegative of the halogens 23. A"borderline"metal that has a high transparency to X-rays 24. A purification process for this metal uses a tetracarbonyl compound 25. The atmospheric gas with the third highest concentration 26. Its simplest hydride is a dimer while its common fluoride is electron deficient 7. This metal suffers from a plague at low temperatures 28. A compound of this metal, auranofin, is used in the treatment of arthritis 29. The sulfide of this metal has an intense yellow color, hence its use as a pigment 30. Discovered by Sir Humphry Davy 83283 Down 1. This member of Group i3 melts at only 30℃. 2. This nonmetal forms ionic, metallic, and covalent compounds. 3. The 2 + ion of this rare earth metal has a half-filled set of f orbitals. 4. The "Tyrannosaurus rex" of the elements. 5. Its compounds were once used to produce glow-in-the-dark watches. 6. This rare earth element was very difficult to separate from its neighbor, praseodymium. 7. Named after the "father" of the periodic table. 8. The bottom member of Group 2, alphabetically. 9. An organometallic compound of this main group metal is used in the preservation of books. 10. The only metal to commonly form a diatomic cation in solution. 11. This metal forms a magnetic oxide of formula M3O4. 12. This gaseous element was once known as "dephlogisticated air." 13. One allotrope is stored under water. 14. Its hexaaqua ion in the +2 oxidation state is pink. 15. This actinoid is usually sold as a compound known as "yellow cake." 16. Xerography would be impossible without this element. 17. Its common oxyanion has a characteristic purple color. 18. The densest non-radioactive metal of Group 9. 19. The highest atomic number element for which stable isotopes are known. 20. The only liquid nonmetal at SATP. 21. Its carbonate is one of the common minerals on the surface of the Earth. 22. The least electronegative of the halogens. 23. A "borderline" metal that has a high transparency to X-rays. 24. A purification process for this metal uses a tetracarbonyl compound. 25. The atmospheric gas with the third highest concentration. 26. Its simplest hydride is a dimer while its common fluoride is electron deficient. 7. This metal suffers from a plague at low temperatures. 28. A compound of this metal, auranofin, is used in the treatment of arthritis. 29. The sulfide of this metal has an intense yellow color, hence its use as a pigment. 30. Discovered by Sir Humphry Davy