Question: Which potential's period 5 is 4 and has an element of Antimony?
SQL: SELECT "potential" FROM "2-161291-1" WHERE "period" = 5.0 AND "element" = 'Antimony';

Question: Which lowest period's element is Ruthenium?
SQL: SELECT MIN("period") FROM "2-161291-1" WHERE "element" = 'Ruthenium';

Question: Which highest period's element is Platinum?
SQL: SELECT MAX("period") FROM "2-161291-1" WHERE "element" = 'Platinum';