Xenon (Xe)
Xenon is element 54, a noble gas in group 18, period 5. A neutral atom has 54 protons, 77 neutrons and 54 electrons, 8 of them valence electrons.
Noble gas- Atomic number
- 54
- Atomic mass
- 131.29 u
- Valence electrons
- 8
- Protons · neutrons
- 54 · 77
- Electrons per shell
- 2, 8, 18, 18, 8
- At room temperature
- gas
Bohr model of xenon
The Bohr model draws xenon as a nucleus of 54 protons and 77 neutrons, with its 54 electrons on 5 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 18 in shell 4, 8 in shell 5. Press Build the atom to watch the shells fill from the inside out. The outer ring (the O 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 xenon
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶
Short form (noble gas notation): [Kr] 5s² 4d¹⁰ 5p⁶. The [Kr] stands for the electrons of krypton, the noble gas before it.
How many valence electrons does xenon have?
Xenon has 8 valence electrons.
Xenon 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 | 54 | equal to the atomic number |
|---|---|---|
| Electrons | 54 | equal to the protons in a neutral atom |
| Neutrons | 77 | mass number 131 − 54 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.
Xenon properties
| Symbol | Xe |
|---|---|
| Category | Noble gas |
| Group · period · block | 18 · 5 · p |
| Atomic mass | 131.29 u |
| State at 25 °C | gas |
| Melting point | 161.4 K (-112 °C, -169 °F) |
| Boiling point | 165 K (-108 °C, -163 °F) |
| Density | 0.0059 g/cm³ |
| Electronegativity (Pauling) | 2.6 |
| Atomic radius | 216 pm |
| First ionization energy | 12.13 eV |
| Electron affinity | — |
| Oxidation states | 0 |
| Common ion charge | 0 |
| Discovered | 1898 by William Ramsay |
Where xenon sits on the periodic table
Group 18: Helium, Neon, Argon, Krypton, Radon, Oganesson.
Questions about xenon
How many valence electrons does xenon have?
Xenon has 8 valence electrons.
How many protons, neutrons and electrons does xenon have?
A neutral xenon atom has 54 protons and 54 electrons. Its most common form has about 77 neutrons (mass number 131 − 54 protons).
What is the electron configuration of xenon?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶, written in short form as [Kr] 5s² 4d¹⁰ 5p⁶.
What does the Bohr model of xenon look like?
A nucleus of 54 protons and 77 neutrons, circled by 5 electron shells holding 2, 8, 18, 18, 8 electrons.
What is the atomic number of xenon?
54. The atomic number is the number of protons in the nucleus, and it is what makes an atom xenon.