Radon (Rn): Bohr Model, Protons, Neutrons & Electrons
Radon is element number 86, a noble gas in group 18, period 6. Its atom has 86 protons, 136 neutrons and 86 electrons arranged in 6 shells: 2, 8, 18, 32, 18, 8.
- 86 protons
- 136 neutrons
- 86 electrons
Protons, neutrons and electrons in radon
Le atomic number of radon is 86, so every radon atom has 86 protons. A neutral atom has the same number of electrons, 86. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For radon-222, that is 222 − 86 = 136 neutrons. Every isotope of radon is radioactive; 222 is the mass number of its most stable one.
How to draw the Bohr model of radon
- Draw the nucleus and write 86 p⁺ et 136 n⁰ inside it.
- Draw the first shell and put 2 electrons on it (the first shell holds at most 2).
- Draw the second shell and put 8 electrons on it.
- Draw the third shell and put 18 electrons on it.
- Draw the fourth shell and put 32 electrons on it.
- Draw the fifth shell and put 18 electrons on it.
- Draw the sixth shell and put 8 electrons on it.
- Check: 2 + 8 + 18 + 32 + 18 + 8 = 86 electrons, the same as the number of protons.
From potassium onwards the shells don’t simply fill as 2, 8, 8: the fourth shell starts before the third is full, so the real arrangement above (2, 8, 18, 32, 18, 8) is the one to draw.
Electron configuration
The electron configuration of radon is [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶. Its 8 outer electrons decide how it reacts: its outer shell is full, so it hardly reacts at all.
Key facts about radon
| Symbol | Rn |
|---|---|
| Atomic number | 86 |
| Relative atomic mass | [222] |
| Group · period · block | group 18 · period 6 · p-block |
| Type | Gaz noble |
| State at 25 °C | gas |
| Couches électroniques | 2, 8, 18, 32, 18, 8 |
| Electron configuration | [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶ |
| Électrons de valence | 8 |
| Common ion | none: its outer shell is already full |
| Electronegativity (Pauling) | 2.20 |
| First ionisation energy | 10.75 eV (1037 kJ/mol) |
| Atomic radius (empirical) | — |
Où radon sits on the periodic table
Foire aux questions
How many protons, neutrons and electrons does radon have?
Radon has 86 protons and 86 electrons (atomic number 86). Its most common isotope, radon-222, has 222 − 86 = 136 neutrons.
What is the electron configuration of radon?
[Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶. In shells that is 2, 8, 18, 32, 18, 8.
How many valence electrons does radon have?
8. Radon is in group 18, and its outer shell holds 8 electrons.
Where is radon on the periodic table?
In group 18, period 6, in the p-block. It is a noble gas.
