111Rg

Roentgenium

Unknown propertiesunknownblock d

A synthetic element that would sit directly beneath gold, made three atoms at a time and gone in seconds, never once observed as a metal.

Atomic number	111
Mass number (longest-lived isotope)	282 g/mol
This element has no stable isotope, so it has no standard atomic weight. The figure above is the mass number of its longest-lived isotope — a convention, not a measurement of a natural mixture.
Group · period	11 · 7
Electron configuration	[Rn] 5f¹⁴ 6d⁹ 7s²

About Roentgenium

Roentgenium was first detected in 1994 at GSI, three atoms from a nickel-on-bismuth reaction, and named for Wilhelm Röntgen, who discovered X-rays in 1895 and took the first Nobel Prize in Physics for it. Sitting under gold, it is one of the more tantalising unmeasured elements: relativistic calculations predict a 6d⁹ 7s² ground state rather than the 6d¹⁰ 7s¹ that copper, silver and gold all adopt, and suggest roentgenium would form a stable −1 anion and might be more reactive than gold rather than less. All of that remains theory. No chemical experiment has been attempted, which is why the category is left unknown.

Use 282 g/mol in these solvers

Moles from Mass (n = m/M)

n = \frac{m}{M}

Opens with M = 282 g/mol already filled in

Gas Density from Molar Mass

\rho = \frac{PM}{RT}

Opens with M = 282 g/mol already filled in

Faraday's Law of Electrolysis (m = QM/nF)

m = \frac{Q M}{n F}

Opens with M = 282 g/mol already filled in

Ion Concentration as CaCO₃ Equivalent

C_{\mathrm{CaCO_3}} = C_{\mathrm{ion}} \times \frac{50.04}{\mathrm{EW}}

Opens with EW = 282 g/mol already filled in

Acid Feed to Reduce Alkalinity

\dot m = \frac{\Delta \mathrm{Alk} \, Q \times \frac{\mathrm{EW}}{50.04}}{p/100\%}

Opens with EW = 282 g/mol already filled in

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