Radon (Rn)
Radon is element 86, a noble gas in group 18, period 6. A neutral atom has 86 protons, 136 neutrons and 86 electrons, 8 of them valence electrons.
Noble gas- Atomic number
- 86
- Atomic mass
- 222.02 u
- Valence electrons
- 8
- Protons · neutrons
- 86 · 136
- Electrons per shell
- 2, 8, 18, 32, 18, 8
- At room temperature
- gas
Bohr model of radon
The Bohr model draws radon as a nucleus of 86 protons and 136 neutrons, with its 86 electrons on 6 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 32 in shell 4, 18 in shell 5, 8 in shell 6. Press Build the atom to watch the shells fill from the inside out. The outer ring (the P 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 radon
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶
Short form (noble gas notation): [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶. The [Xe] stands for the electrons of xenon, the noble gas before it.
How many valence electrons does radon have?
Radon has 8 valence electrons.
Radon is in group 18, and for groups 13–18 you subtract 10 from the group number: 18 − 10 = 8. A full outer shell of eight makes it a noble gas that rarely reacts.
Protons, neutrons and electrons
| Protons | 86 | equal to the atomic number |
|---|---|---|
| Electrons | 86 | equal to the protons in a neutral atom |
| Neutrons | 136 | mass number 222 − 86 protons |
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.
Radon properties
| Symbol | Rn |
|---|---|
| Category | Noble gas |
| Group · period · block | 18 · 6 · p |
| Atomic mass | 222.02 u |
| State at 25 °C | gas |
| Melting point | 202 K (-71.1 °C, -96.1 °F) |
| Boiling point | 211.4 K (-61.7 °C, -79.1 °F) |
| Density | 0.0097 g/cm³ |
| Electronegativity (Pauling) | — |
| Atomic radius | 220 pm |
| First ionization energy | 10.745 eV |
| Electron affinity | — |
| Oxidation states | 0 |
| Common ion charge | 0 |
| Discovered | 1900 by Friedrich Ernst Dorn |
Where radon sits on the periodic table
Group 18: Helium, Neon, Argon, Krypton, Xenon, Oganesson.
Questions about radon
How many valence electrons does radon have?
Radon has 8 valence electrons.
How many protons, neutrons and electrons does radon have?
A neutral radon atom has 86 protons and 86 electrons. Its most common form has about 136 neutrons (mass number 222 − 86 protons).
What is the electron configuration of radon?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶, written in short form as [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶.
What does the Bohr model of radon look like?
A nucleus of 86 protons and 136 neutrons, circled by 6 electron shells holding 2, 8, 18, 32, 18, 8 electrons.
What is the atomic number of radon?
86. The atomic number is the number of protons in the nucleus, and it is what makes an atom radon.