35. What are the symbols of the following metals: sodium, radium, iron, gold, manganese, lead. 36. What are the symbols of the following nonmetals: fluorine, chlo- rine, bromine, sulfur, oxygen, phosphorus? 37. Give the names of the metals that correspond to the following symbols: Sn. Pt, Hg. Mg, K, Ag. 38. Give the names of the nonmetals that correspond to the follow- ing symbols: As, I, Xe, He, C. Si. 39. a. Classify the following elements as metals or nonmetals: Mg Si Rn Ti Ge Eu Au B Am Bi At Br b. The distinction between metals and nonmetals is really not a clear one. Some elements, called metalloids, are intermediate in their properties. Which of these elements would you reclassify as metalloids? What other elements in the periodic table would you expect to be metalloids? 40. a. List the noble gas elements. Which of the noble gases has only radioactive isotopes? (This situation is indicated on most peri- odic tables by parentheses around the mass of the element. See inside front cover.) b. Which lanthanide element and which transition element have only radioactive isotopes?