Atomic Structure and Periodic Trends

Atomic Structure and Periodic Trends - Higher Difficulty Problems

Q. What is the effective nuclear charge (Z_eff) experienced by a 3p electron in phosphorus (atomic number 15)?

Solution

Using Slater's rules, Z_eff = Z - S. For P, Z = 15 and S = 8, so Z_eff = 15 - 8 = 7.

Correct Answer: C — 7

Q. What is the electron configuration of the element with atomic number 30?

Solution

The element with atomic number 30 is Zn. Its electron configuration is [Ar] 4s2 3d10.

Correct Answer: A — [Ar] 4s2 3d10

Q. What is the principal quantum number of the outermost electrons in a chlorine atom?

Solution

Chlorine has an atomic number of 17, and its outermost electrons are in the 3rd shell (n=3).

Correct Answer: B — 3

Q. Which of the following elements has the lowest first ionization energy?

Solution

Boron has a lower first ionization energy than Be, C, and N due to its position in the periodic table.

Correct Answer: B — B

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