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Use the periodic table to determine the electron configuration for Si and [tex]Y[/tex] in noble-gas notation.

Si:
A. [tex][\text{He}] 2s^2 2p^6 3s^2 3p^5[/tex]
B. [tex][\text{Ar}] 4s^2 4p^5[/tex]
C. [tex][\text{Ne}] 3s^2 3p^2[/tex]
D. [tex][\text{Ne}] 3s^2 3p^4[/tex]


Sagot :

Sure, let's determine the electron configurations for Silicon (Si) and Yttrium (Y) in noble-gas notation. I will guide you through the process step-by-step.

### Silicon (Si)

1. Determine the atomic number: Silicon has an atomic number of 14.

2. Write out the full electron configuration:
- The first 2 electrons go into the 1s orbital: [tex]\(1s^2\)[/tex]
- The next 2 electrons go into the 2s orbital: [tex]\(2s^2\)[/tex]
- The next 6 electrons fill the 2p orbital: [tex]\(2p^6\)[/tex]
- The next 2 electrons occupy the 3s orbital: [tex]\(3s^2\)[/tex]
- The final 2 electrons go into the 3p orbital: [tex]\(3p^2\)[/tex]

Therefore, the full electron configuration is: [tex]\(1s^2 2s^2 2p^6 3s^2 3p^2\)[/tex]

3. Convert to noble-gas notation:
- The nearest preceding noble gas to silicon is Neon (Ne), which has the electron configuration [tex]\(1s^2 2s^2 2p^6\)[/tex].
- Thus, we can write Silicon's electron configuration in noble-gas notation as: [tex]\([Ne] 3s^2 3p^2\)[/tex]

So, the correct noble-gas notation for Silicon is:
[tex]\[ [Ne] 3s^2 3p^2 \][/tex]

### Yttrium (Y)

1. Determine the atomic number: Yttrium has an atomic number of 39.

2. Write out the full electron configuration:
- The first 2 electrons fill the 1s orbital: [tex]\(1s^2\)[/tex]
- The next 2 electrons fill the 2s orbital: [tex]\(2s^2\)[/tex]
- The next 6 electrons fill the 2p orbital: [tex]\(2p^6\)[/tex]
- The next 2 electrons fill the 3s orbital: [tex]\(3s^2\)[/tex]
- The next 6 electrons fill the 3p orbital: [tex]\(3p^6\)[/tex]
- The next 2 electrons fill the 4s orbital: [tex]\(4s^2\)[/tex]
- The next 10 electrons fill the 3d orbital: [tex]\(3d^{10}\)[/tex]
- The next 6 electrons fill the 4p orbital: [tex]\(4p^6\)[/tex]
- The next 2 electrons fill the 5s orbital: [tex]\(5s^2\)[/tex]
- The final electron goes into the 4d orbital: [tex]\(4d^1\)[/tex]

Therefore, the full electron configuration is:
[tex]\(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^1\)[/tex]

3. Convert to noble-gas notation:
- The nearest preceding noble gas to yttrium is Krypton (Kr), which has the electron configuration [tex]\(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6\)[/tex].
- Thus, we can write Yttrium's electron configuration in noble-gas notation as: [tex]\([Kr] 5s^2 4d^1\)[/tex]

So, the correct noble-gas notation for Yttrium is:
[tex]\[ [Kr] 5s^2 4d^1 \][/tex]

If you have any questions or need further clarification, feel free to ask!