Used to remove oxygen from vacuum tubes, this metal will melt in your hand and catch fire in air. Found in the mineral pollucite, its chloride salt is used in optical instruments and [*] photoelectric cells. The first element to be discovered with a spectroscope—for 10 points—name this element, more reactive than its fellow alkali potassium, an isotope of which is used in atomic clocks.
Used to remove oxygen from vacuum tubes, this metal will melt in your hand and catch fire in air. Found in the mineral pollucite, its chloride salt is used in optical instruments and [*] photoelectric cells. The first element to be discovered with a spectroscope—for 10 points—name this element, more reactive than its fellow alkali potassium, an isotope of which is used in atomic clocks.
Used to remove oxygen from vacuum tubes, this metal will melt in your hand and catch fire in air.
cesium or Cs