Sure, let's carefully analyze the options to determine the correct noble gas configuration for Cobalt (Co).
1. Understand Cobalt's Electron Configuration:
- The atomic number of Cobalt (Co) is 27, which means it has 27 electrons.
- The ground state electron configuration of Co is: [tex]\(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^7\)[/tex].
2. Determine the Noble Gas Core:
- The noble gas preceding Cobalt is Argon (Ar), which has an atomic number of 18.
- Argon's electron configuration is [tex]\(1s^2 2s^2 2p^6 3s^2 3p^6\)[/tex].
3. Express Cobalt's Configuration in Noble Gas Notation:
- Using the noble gas shorthand, we replace the configuration up to Argon with [Ar].
- We then add the remaining electrons that come after Argon: [tex]\(4s^2 3d^7\)[/tex].
Hence, the correct noble gas notation for Cobalt (Co) should be [tex]\([\operatorname{Ar}] 4s^2 3d^7\)[/tex].
4. Examine the Given Options:
- Option A: [tex]\([\operatorname{Co}] 4s^2 3d^7\)[/tex]
- This option is not correct because it uses Co instead of Ar for the noble gas core, which is incorrect notation.
- Option B: [tex]\([\operatorname{Ar}] 4s^2 4p^6 3d^1\)[/tex]
- This is not correct because it incorrectly includes [tex]\(4p^6\)[/tex] orbitals, which would correspond to elements beyond Cobalt.
- Option C: [tex]\([Kr] 4s^2 4p^6 4d^1\)[/tex]
- This is also incorrect because Krypton (Kr) is not the correct preceding noble gas for Co and involves incorrect orbitals for Co.
- Option D: [tex]\([\operatorname{Ar}] 4s^2 3d^7\)[/tex]
- This is correct as it matches the correct noble gas configuration notation for Cobalt (Co).
After careful consideration, the correct noble gas configuration for Cobalt (Co) is option:
D. [tex]\([\operatorname{Ar}] 4s^2 3d^7\)[/tex]
