Group 6, numbered by IUPAC style, is a group of elements in the periodic table. Its members are chromium (Cr), molybdenum (Mo), tungsten (W), and seaborgium (Sg). These are all transition metals and chromium, molybdenum and tungsten are refractory metals. The period 8 elements of group 6 are likely to be either unpenthexium (Uph) or unpentoctium (Upo). This may not be possible; drip instability may imply that the periodic table ends at unbihexium. Neither unpenthexium nor unpentoctium have been synthesized, and it is unlikely that this will happen in the near future.