Question

1. determine the highest occupied energy level in the following elements:

a. he
b. be
c. al
d. ca
e. sn

Explanation:

Step1: Find atomic number of He

Atomic number of He = 2, electron configuration: $1s^2$. Highest energy level is the principal quantum number of the outermost orbital, so $n=1$.

Step2: Find atomic number of Be

Atomic number of Be = 4, electron configuration: $1s^22s^2$. Highest energy level: $n=2$.

Step3: Find atomic number of Al

Atomic number of Al = 13, electron configuration: $1s^22s^22p^63s^23p^1$. Highest energy level: $n=3$.

Step4: Find atomic number of Ca

Atomic number of Ca = 20, electron configuration: $1s^22s^22p^63s^23p^64s^2$. Highest energy level: $n=4$.

Step5: Find atomic number of Sn

Atomic number of Sn = 50, electron configuration: $1s^22s^22p^63s^23p^63d^{10}4s^24p^64d^{10}5s^25p^2$. Highest energy level: $n=5$.

Answer:

a. 1
b. 2
c. 3
d. 4
e. 5