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Astronomy Chemical element

Roentgenium

Roentgenium (Rg) is a synthetic, highly radioactive chemical element belonging to the category Transition metal, with atomic number 111 and atomic mass 282.0000 u (based on its most stable known isotope). This sheet describes its fundamental properties, position in the periodic table and physical characteristics.

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Astronomy · Chemical element

Roentgenium

EL33

Roentgenium (Rg)

Identity

  • Name: Roentgenium
  • Symbol: Rg
  • Atomic number: 111
  • Atomic mass: 282.0000 u

Position in the periodic table

  • Group: 11
  • Period: 7
  • Category: Transition metal

Physico-chemical properties

  • Standard state: Presumably solid (synthetic, not observed in bulk)
  • Melting point: Unknown (predicted to be very high)
  • Density: Unknown (probably very high)
  • Electron configuration: [Rn] 5f¹⁴ 6d⁹ 7s² (predicted)

Scientific description

Roentgenium is a synthetic, highly radioactive chemical element with symbol Rg and atomic number 111. It belongs to the category of Transition metal and occupies group 11 and period 7 in the periodic table. No stable isotopes are known; the value 282.0000 u corresponds to the most stable known isotope. Because only a few atoms have ever been produced, its macroscopic physical properties such as melting point, density and crystal structure remain unknown and are estimated from theoretical calculations.