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

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

Y:
A. [tex][Kr] 5s^2 4d^1[/tex]
B. [tex][Xe] 6s^2 4f^14 5d^1[/tex]
C. [tex][Ar] 4s^2 3d^1[/tex]
D. [tex][Kr] 5s^2 4p^1[/tex]



Answer :

Sure, let's determine the electron configuration for Si (Silicon) and Y (Yttrium) using noble-gas notation. The options provided will help us distinguish the correct configuration for Si, and I will guide you through both elements.

### Silicon (Si)

1. Atomic number of Silicon (Si): 14.
2. Electron Configuration Strategy: Start from the nearest noble gas before silicon in the periodic table, which is Neon (Ne), atomic number 10.
3. Electron Configuration Steps:
- Neon (Ne) has the configuration: [tex]\(1s^2 2s^2 2p^6\)[/tex].
- Beyond Neon, we need to account for 4 more electrons (since Si has atomic number 14 and Ne covers 10 electrons).
- Next orbitals after Ne: [tex]\(3s\)[/tex] and [tex]\(3p\)[/tex].

The electronic configuration would continue as follows:
[tex]\[ 3s^2 3p^2 \][/tex]

4. Noble-gas notation for Silicon (Si):
[tex]\[ [ Ne ] 3s^2 3p^2 \][/tex]

### Yttrium (Y)

1. Atomic number of Yttrium (Y): 39.
2. Electron Configuration Strategy: Start from the nearest noble gas before yttrium in the periodic table, which is Krypton (Kr), atomic number 36.
3. Electron Configuration Steps:
- Krypton (Kr) has the configuration: [tex]\(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6\)[/tex].
- Beyond Krypton, we need to account for 3 more electrons (since Y has atomic number 39 and Kr covers 36 electrons).
- Next orbitals after Kr: [tex]\(5s\)[/tex] and [tex]\(4d\)[/tex].

The electronic configuration would continue as follows:
[tex]\[ 5s^2 4d^1 \][/tex]

4. Noble-gas notation for Yttrium (Y):
[tex]\[ [ Kr ] 5s^2 4d^1 \][/tex]

### Summary:
- Silicon (Si): [tex]\([ Ne ] 3s^2 3p^2\)[/tex]
- Yttrium (Y): [tex]\([ Kr ] 5s^2 4d^1\)[/tex]

By utilizing these steps, we derive the correct noble-gas notations for both elements.