Xenon (Xe) is a noble gas known for its stable electron arrangement. But sometimes, it can gain an electron to form a negative ion called the -1 anion. This article explains the subshell for Xe to form -1 anion in simple terms, covering electron configurations and how xenon gains that extra electron.
What is an Anion?
An anion is an atom or molecule that has gained one or more extra electrons. These extra electrons give it a negative charge. For xenon to form an anion with a -1 charge, it must gain one electron. This changes its electron arrangement, which involves specific subshells.
Electron Configuration of Xenon (Xe)
Before we talk about the anion, let’s look at neutral xenon’s electron setup. Xenon has 54 electrons. Its electron configuration is:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶
The last electrons are in the 5p subshell. Xenon has a full outer shell, making it very stable and less likely to react under normal conditions.
What Happens When Xenon Gains an Electron?
When xenon gains one electron to form Xe⁻ (the -1 anion), the extra electron must enter the next available subshell or orbital. Since xenon’s 5p subshell is already full, the electron will enter the next higher energy level, which is the 6s subshell.
Subshell for Xe to Form -1 Anion
The subshell for Xe to form -1 anion is the 6s subshell. This means the extra electron goes into the 6s orbital. This is because all lower energy orbitals are already filled in xenon’s neutral state. Adding an electron here changes the electron configuration to:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s¹
Why Does the Electron Enter the 6s Subshell?
Electrons fill orbitals starting from the lowest energy level. Since 5p is full, the next available place is 6s. This follows the Aufbau principle in chemistry, which states electrons fill the lowest energy orbitals first.
Is Xenon Anion Common?
Xenon is a noble gas with a full outer shell. It rarely gains electrons because it is already stable. However, under special conditions such as in plasma or with strong electron donors, Xe can form the -1 anion by gaining an electron in the 6s subshell.
Key Points on Subshell for Xe to Form -1 Anion
- Xenon normally has 54 electrons filling up to the 5p subshell.
- The -1 anion means xenon has gained one extra electron.
- This extra electron goes into the 6s subshell.
- The electron configuration changes to include 6s¹.
- Forming the anion is rare and happens under special conditions.
What Does This Mean Chemically?
The formation of Xe⁻ changes its chemical behavior. The extra electron in the 6s subshell can affect xenon’s reactivity. While xenon is usually unreactive, gaining an electron can make it more reactive in some chemical environments.
How Does Electron Affinity Relate?
Electron affinity is the energy change when an atom gains an electron. Xenon has low electron affinity because it is stable already. This is why forming the Xe⁻ ion is rare and requires special conditions.
Summary of Electron Configuration Change
| State | Electron Count | Electron Configuration |
| Neutral Xe | 54 | 1s²… 5p⁶ |
| Xe⁻ Anion | 55 | 1s²… 5p⁶ 6s¹ |
Conclusion
The subshell for Xe to form -1 anion is the 6s subshell. When xenon gains an electron, the extra electron fills the 6s orbital because all lower orbitals are full. This process is rare because xenon is a noble gas with a full outer shell. Understanding this helps explain how even stable atoms can sometimes form ions.
FAQs
Which subshell does the extra electron occupy when xenon forms a -1 anion?
The extra electron enters the 6s subshell because all the lower energy subshells, including 5p, are already full in neutral xenon.
Why can’t the extra electron enter the 5p subshell in Xe⁻?
The 5p subshell is fully occupied with six electrons in neutral xenon, so the next available subshell is 6s for the extra electron.
Is the formation of Xe⁻ (xenon -1 anion) common?
No, it is very rare because xenon is a noble gas with a stable electron configuration and does not easily gain electrons under normal conditions.
How does adding an electron affect xenon’s electron configuration?
Adding one electron changes the configuration from ending in 5p⁶ to having an extra electron in 6s¹, making it:
1s² … 5p⁶ 6s¹.
What role does electron affinity play in Xe forming a -1 anion?
Xenon’s low electron affinity means it doesn’t easily accept extra electrons, which is why forming the -1 anion requires special conditions.
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