Rare metallic elements are chemical elements that are not found in abundance in nature. TANTALUM (8 letters) is a rare metallic element that is used in the production of electronic components, such as capacitors and transistors. Yttrium (7 letters) is another rare metallic element that is used in the production of television and computer screens. Cesium (6 letters) is a rare metallic element that is used in atomic clocks and other precision instruments.