Answer :
To determine the correct electron configurations for zinc (Zn) and technetium (Tc) using noble gas notation, let's go through the options and analyze them step-by-step.
### Zinc (Zn)
1. [Ar] [tex]$4s^2 3d^{10}$[/tex]
- This option uses Argon (Ar) as the noble gas core.
- After Argon, the electrons fill the 4s orbital and then the 3d orbital.
- Total electrons: [tex]\(18 \text{ (from Argon)} + 2 \text{ (from 4s)} + 10 \text{ (from 3d)} = 30\)[/tex]
- Zinc has an atomic number of 30, so this configuration matches the total number of electrons for Zn.
- This option seems correct.
2. [Ne] [tex]$3s^2 3p^6 4s^2 3d^{10}$[/tex]
- This option uses Neon (Ne) as the noble gas core.
- After Neon, it lists:
- [tex]$3s^2$[/tex]: 2 electrons
- [tex]$3p^6$[/tex]: 6 electrons
- [tex]$4s^2$[/tex]: 2 electrons
- [tex]$3d^{10}$[/tex]: 10 electrons
- Total electrons: [tex]\(10 \text{ (from Neon)} + 2 \text{ (from 3s)} + 6 \text{ (from 3p)} + 2 \text{ (from 4s)} + 10 \text{ (from 3d)} = 30\)[/tex]
- While the total number of electrons matches Zn, it is not in the correct order for nobel gas notation relative to Argon.
3. [tex]$[Ar] 4s^2 3d^9$[/tex]
- This option uses Argon (Ar) as the noble gas core.
- After Argon, it lists 4s orbital before the 3d orbital.
- Total electrons: [tex]\(18 \text{ (from Argon)} + 2 \text{ (from 4s)} + 9 \text{ (from 3d)} = 29\)[/tex]
- Since Zinc has an atomic number of 30, this configuration is incorrect.
4. [Ar] [tex]$4s^2 4d^{10}$[/tex]
- This option uses Argon (Ar) as the noble gas core.
- It wrongly skips the 3d orbital completely and jumps to 4d orbital.
- Total electrons: [tex]\(18 \text{ (from Argon)} + 2 \text{ (from 4s)} + 10 \text{ (from 4d)} = 30\)[/tex]
- Although the total is 30, the order of filling is incorrect as 3d should be filled before 4d.
Thus, the correct electron configuration for zinc (Zn) is:
[Ar] [tex]$4s^2 3d^{10}$[/tex]
### Technetium (Tc)
1. [Kr] [tex]$5s^2 4d^5$[/tex]
- This option uses Krypton (Kr) as the noble gas core.
- After Krypton, it lists:
- [tex]$5s^2$[/tex]: 2 electrons
- [tex]$4d^5$[/tex]: 5 electrons
- Total electrons: [tex]\(36 \text{ (from Krypton)} + 2 \text{ (from 5s)} + 5 \text{ (from 4d)} = 43\)[/tex]
- Technetium has an atomic number of 43, so this configuration matches the total number of electrons.
- This option seems correct.
2. [Kr] [tex]$4d^6$[/tex]
- This option only includes the 4d orbital, which seems incorrect because the 5s orbital should be filled first.
- Total electrons: [tex]\(36 \text{ (from Krypton)} + 6 \text{ (from 4d)} = 42\)[/tex]
- This does not match the atomic number of Technetium (43).
3. [Xe] [tex]$4f^{14} 5d^7$[/tex]
- This option uses Xenon (Xe) as the noble gas core.
- After Xenon it incorrectly continue with 4f and 5d, which should include 5s and 4d first.
- Total electrons: [tex]\(54 \text{ (from Xenon)} + 14 \text{ (from 4f)} + 7 \text{ (from 5d)} = 75\)[/tex]
- This total does not match the atomic number of Technetium (43).
4. [Xe] [tex]$4f^{14} 5d^6$[/tex]
- This option uses Xenon (Xe) as the noble gas core.
- Similar to the previous one, this is incorrect sequence and does not fill the correct lower orbitals first.
- Total electrons: [tex]\(54 \text{ (from Xenon)} + 14 \text{ (from 4f)} + 6 \text{ (from 5d)} = 74\)[/tex]
- This total also does not match the atomic number of Technetium (43).
Thus, the correct electron configuration for technetium (Tc) is:
[Kr] [tex]$5s^2 4d^5$[/tex]
Therefore, the correct electron configurations are:
- Zinc (Zn): [Ar] [tex]$4s^2 3d^{10}$[/tex]
- Technetium (Tc): [Kr] [tex]$5s^2 4d^5$[/tex]
### Zinc (Zn)
1. [Ar] [tex]$4s^2 3d^{10}$[/tex]
- This option uses Argon (Ar) as the noble gas core.
- After Argon, the electrons fill the 4s orbital and then the 3d orbital.
- Total electrons: [tex]\(18 \text{ (from Argon)} + 2 \text{ (from 4s)} + 10 \text{ (from 3d)} = 30\)[/tex]
- Zinc has an atomic number of 30, so this configuration matches the total number of electrons for Zn.
- This option seems correct.
2. [Ne] [tex]$3s^2 3p^6 4s^2 3d^{10}$[/tex]
- This option uses Neon (Ne) as the noble gas core.
- After Neon, it lists:
- [tex]$3s^2$[/tex]: 2 electrons
- [tex]$3p^6$[/tex]: 6 electrons
- [tex]$4s^2$[/tex]: 2 electrons
- [tex]$3d^{10}$[/tex]: 10 electrons
- Total electrons: [tex]\(10 \text{ (from Neon)} + 2 \text{ (from 3s)} + 6 \text{ (from 3p)} + 2 \text{ (from 4s)} + 10 \text{ (from 3d)} = 30\)[/tex]
- While the total number of electrons matches Zn, it is not in the correct order for nobel gas notation relative to Argon.
3. [tex]$[Ar] 4s^2 3d^9$[/tex]
- This option uses Argon (Ar) as the noble gas core.
- After Argon, it lists 4s orbital before the 3d orbital.
- Total electrons: [tex]\(18 \text{ (from Argon)} + 2 \text{ (from 4s)} + 9 \text{ (from 3d)} = 29\)[/tex]
- Since Zinc has an atomic number of 30, this configuration is incorrect.
4. [Ar] [tex]$4s^2 4d^{10}$[/tex]
- This option uses Argon (Ar) as the noble gas core.
- It wrongly skips the 3d orbital completely and jumps to 4d orbital.
- Total electrons: [tex]\(18 \text{ (from Argon)} + 2 \text{ (from 4s)} + 10 \text{ (from 4d)} = 30\)[/tex]
- Although the total is 30, the order of filling is incorrect as 3d should be filled before 4d.
Thus, the correct electron configuration for zinc (Zn) is:
[Ar] [tex]$4s^2 3d^{10}$[/tex]
### Technetium (Tc)
1. [Kr] [tex]$5s^2 4d^5$[/tex]
- This option uses Krypton (Kr) as the noble gas core.
- After Krypton, it lists:
- [tex]$5s^2$[/tex]: 2 electrons
- [tex]$4d^5$[/tex]: 5 electrons
- Total electrons: [tex]\(36 \text{ (from Krypton)} + 2 \text{ (from 5s)} + 5 \text{ (from 4d)} = 43\)[/tex]
- Technetium has an atomic number of 43, so this configuration matches the total number of electrons.
- This option seems correct.
2. [Kr] [tex]$4d^6$[/tex]
- This option only includes the 4d orbital, which seems incorrect because the 5s orbital should be filled first.
- Total electrons: [tex]\(36 \text{ (from Krypton)} + 6 \text{ (from 4d)} = 42\)[/tex]
- This does not match the atomic number of Technetium (43).
3. [Xe] [tex]$4f^{14} 5d^7$[/tex]
- This option uses Xenon (Xe) as the noble gas core.
- After Xenon it incorrectly continue with 4f and 5d, which should include 5s and 4d first.
- Total electrons: [tex]\(54 \text{ (from Xenon)} + 14 \text{ (from 4f)} + 7 \text{ (from 5d)} = 75\)[/tex]
- This total does not match the atomic number of Technetium (43).
4. [Xe] [tex]$4f^{14} 5d^6$[/tex]
- This option uses Xenon (Xe) as the noble gas core.
- Similar to the previous one, this is incorrect sequence and does not fill the correct lower orbitals first.
- Total electrons: [tex]\(54 \text{ (from Xenon)} + 14 \text{ (from 4f)} + 6 \text{ (from 5d)} = 74\)[/tex]
- This total also does not match the atomic number of Technetium (43).
Thus, the correct electron configuration for technetium (Tc) is:
[Kr] [tex]$5s^2 4d^5$[/tex]
Therefore, the correct electron configurations are:
- Zinc (Zn): [Ar] [tex]$4s^2 3d^{10}$[/tex]
- Technetium (Tc): [Kr] [tex]$5s^2 4d^5$[/tex]
