electron configuration of ru3+, as3-, y3+ pd2+ and au3+. determine which one has noble gas configuration
The Correct Answer and Explanation is:
To determine the electron configurations of the ions Ru³⁺, As³⁻, Y³⁺, Pd²⁺, and Au³⁺, and find out which one has a noble gas configuration, we follow these steps:
1. Determine the Atomic Number (Z):
- Ru (Ruthenium): 44
- As (Arsenic): 33
- Y (Yttrium): 39
- Pd (Palladium): 46
- Au (Gold): 79
2. Write the Ground-State Electron Configurations (Neutral Atoms):
- Ru: [Kr] 5s¹ 4d⁷
- As: [Ar] 4s² 3d¹⁰ 4p³
- Y: [Kr] 5s² 4d¹
- Pd: [Kr] 4d¹⁰
- Au: [Xe] 6s¹ 4f¹⁴ 5d¹⁰
3. Determine the Ion Configurations:
✅ Ru³⁺ (remove 3 electrons)
From 5s and 4d:
Ru³⁺ = [Kr] 4d⁵
✅ As³⁻ (add 3 electrons)
Fill 4p:
As³⁻ = [Kr] (As gains 3 electrons to complete 4p⁶)
✅ Noble gas configuration!
✅ Y³⁺ (remove 3 electrons)
From 5s² and 4d¹:
Y³⁺ = [Kr]
✅ Noble gas configuration!
✅ Pd²⁺ (remove 2 electrons)
From 4d¹⁰, assume they come from filled d orbitals (since 5s is empty in Pd):
Pd²⁺ = [Kr] 4d⁸
✅ Au³⁺ (remove 3 electrons)
From 6s¹ and 5d¹⁰:
Au³⁺ = [Xe] 4f¹⁴ 5d⁸
Conclusion: Which Have Noble Gas Configuration?
- ✅ As³⁻ = [Kr] — Noble gas configuration (matches Kr)
- ✅ Y³⁺ = [Kr] — Noble gas configuration (matches Kr)
Explanation (300+ words):
Electron configuration describes the arrangement of electrons in an atom’s orbitals. For ions, this configuration changes based on whether electrons are added (in anions) or removed (in cations).
Let’s start with As³⁻, the arsenic anion. Arsenic has 33 electrons normally, with a configuration ending in 4p³. When it gains 3 electrons, the 4p subshell becomes full (4p⁶), matching the configuration of krypton (Kr), a noble gas. This gives As³⁻ a noble gas configuration, which is highly stable due to a completely filled outer shell.
Y³⁺, yttrium’s 3+ ion, starts with 39 electrons. Losing 3 electrons removes its 5s² and 4d¹ electrons, leaving it with 36 electrons — again, the configuration of krypton ([Kr]). Hence, Y³⁺ also attains a noble gas configuration.
Ru³⁺, on the other hand, loses three electrons (from 5s and 4d) but ends up with 4d⁵ electrons beyond the krypton core, which means it does not match a noble gas.
Pd²⁺ loses 2 electrons, resulting in 4d⁸ — still not a noble gas configuration. Similarly, Au³⁺ ends up with [Xe] 4f¹⁴ 5d⁸ — again, not a noble gas.
In summary, only As³⁻ and Y³⁺ achieve the electron configuration of a noble gas — krypton in both cases. This stability reflects the tendency of atoms and ions to achieve filled electron shells, a key principle in chemical bonding and ion formation.