Roentgenium (Rg)
Roentgenium is element 111, a transition metal in group 11, period 7. A neutral atom has 111 protons, 171 neutrons and 111 electrons, 2 of them valence electrons. Many of its properties are predicted, because only a few atoms have ever been made.
Transition metal- Atomic number
- 111
- Atomic mass
- [282] u
- Valence electrons
- 2*
- Protons · neutrons
- 111 · 171
- Electrons per shell
- 2, 8, 18, 32, 32, 17, 2
- At room temperature
- solid (expected)
Bohr model of roentgenium
The Bohr model draws roentgenium as a nucleus of 111 protons and 171 neutrons, with its 111 electrons on 7 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 32 in shell 4, 32 in shell 5, 17 in shell 6, 2 in shell 7. Press Build the atom to watch the shells fill from the inside out. The outer ring (the Q shell) is dashed: the electrons there are the ones that take part in chemistry.
Real electrons don't travel in neat circles. They live in fuzzy orbitals, shown below, but the Bohr picture is the quickest way to count shells and valence electrons.
Electron configuration of roentgenium
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d⁹
Short form (noble gas notation): [Rn] 7s² 5f¹⁴ 6d⁹. The [Rn] stands for the electrons of radon, the noble gas before it.
This configuration is predicted from calculations; it has not been measured.
How many valence electrons does roentgenium have?
Roentgenium has 2 valence electrons.
Roentgenium is a transition metal, so its valence electrons are less clear-cut than for main-group elements. It has 2 electrons in its outermost shell (shell 7), and electrons in its inner d subshell can also take part in bonding.
Protons, neutrons and electrons
| Protons | 111 | equal to the atomic number |
|---|---|---|
| Electrons | 111 | equal to the protons in a neutral atom |
| Neutrons | 171 | mass number 282 − 111 protons (for its longest-lived isotope, Rg-282) |
Atoms of the same element can have different numbers of neutrons (isotopes). The count above uses the rounded atomic mass, the way it's taught in class.
Roentgenium properties
| Symbol | Rg |
|---|---|
| Category | Transition metal |
| Group · period · block | 11 · 7 · d |
| Atomic mass | [282] u |
| State at 25 °C | solid (expected) |
| Melting point | — |
| Boiling point | — |
| Density | — |
| Electronegativity (Pauling) | — |
| Atomic radius | — |
| First ionization energy | — |
| Electron affinity | — |
| Oxidation states | 5, 3, 1, −1 |
| Common ion charge | 5, 3 |
| Discovered | 1994 by Gesellschaft für Schwerionenforschung |
Where roentgenium sits on the periodic table
Group 11: Copper, Silver, Gold.
Questions about roentgenium
How many valence electrons does roentgenium have?
Roentgenium has 2 valence electrons in its outer shell; inner d or f electrons can also bond.
How many protons, neutrons and electrons does roentgenium have?
A neutral roentgenium atom has 111 protons and 111 electrons. Its most common form has about 171 neutrons (mass number 282 − 111 protons).
What is the electron configuration of roentgenium?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d⁹, written in short form as [Rn] 7s² 5f¹⁴ 6d⁹. This configuration is predicted, not measured.
What does the Bohr model of roentgenium look like?
A nucleus of 111 protons and 171 neutrons, circled by 7 electron shells holding 2, 8, 18, 32, 32, 17, 2 electrons.
What is the atomic number of roentgenium?
111. The atomic number is the number of protons in the nucleus, and it is what makes an atom roentgenium.