Question 1

Which of the following best explains why d subshell orbitals are most stable when they are half-filled or fully-filled?

Accepted Answer

Because half-filled and fully-filled d subshells have maximum symmetry and exchange energy.

Question 2

What is the condensed electron configuration for chromium (Cr, Z = 24), considering the exception to the expected filling order?

Accepted Answer

$$[Ar] \ 4s^1$ \ 3d^5$

Question 3

Which element's electron configuration is an example of an s electron being promoted to create a completely-filled d subshell?

Accepted Answer

Copper (Cu, Z = 29)

Question 4

Given the electron configuration $$[Kr] \ 5s^1$ \ 4d^5$ for molybdenum (Mo, Z = 42), which principle does this configuration illustrate?

Accepted Answer

Exception to the Aufbau principle for increased d subshell stability.

Question 5

Which of the following is the correct condensed electron configuration for gold (Au, Z = 79)?

Accepted Answer

$$[Xe] \ 6s^1$ \ 4f$$^{14}$$ \ 5d$$^{10}$$

Question 6

Why does copper (Cu, Z = 29) have the electron configuration $$[Ar] \ 4s^1$ \ 3d$$^{10}$$ instead of $$[Ar] \ $$4s^2$$ \ $$3d^9$$?

Accepted Answer

A completely-filled d subshell ($$3d^{10}) is $$more stable due to symmetry and exchange energy.

Question 7

Which of the following statements about the electron configurations of palladium (Pd) and silver (Ag) is correct?

Accepted Answer

Ag has 2 more electrons and the same number of s electrons as Pd.

Question 8

Which of the following is a real-world consequence of the electron configuration exceptions in transition metals?

Accepted Answer

They affect the color and magnetic properties of compounds formed by these metals.

Question 9

If an atom has the electron configuration $$[Ar] \ 4s^2$ \ 3d^6$, which element is it?

Accepted Answer

Iron (Fe, Z = 26)

Question 10

Which electron configuration represents a half-filled d subshell?

Accepted Answer

$$3d^5$$

Question 11

A patient is exposed to a compound containing molybdenum. Which electron configuration would you expect for Mo in its ground state, considering known exceptions?

Accepted Answer

$$[Kr] \ 5s^1$ \ 4d^5$

Question 12

Which of the following best describes the electron configuration of silver (Ag, Z = 47)?

Accepted Answer

$$[Kr] \ 5s^1$ \ 4d$$^{10}$$

Question 13

Which principle is violated in the electron configuration exception for chromium (Cr)?

Accepted Answer

Aufbau principle

Question 14

What is the main reason for the observed electron configuration exceptions in elements like Mo, Cr, Cu, and Ag?

Accepted Answer

Increased stability due to half-filled or fully-filled d subshells.

Question 15

Which of the following electron configurations is NOT an exception to the expected filling order?

Accepted Answer

$$[Ar] \ 4s^2$ \ 3d^6$

Question 16

A scientist is analyzing the electron configuration of a transition metal and finds $$[Ar] \ 4s^1$ \ 3d^5$. Which element is being analyzed?

Accepted Answer

Chromium (Cr)

Question 17

Which of the following elements has a completely-filled d subshell in its ground state electron configuration?

Accepted Answer

Copper (Cu, Z = 29)

Question 18

Which electron configuration would you expect for zinc (Zn, Z = 30)?

Accepted Answer

$$[Ar] \ 4s^2$ \ 3d$$^{10}$$

Question 19

Which of the following is a correct statement about the electron configuration of transition metals?

Accepted Answer

Some transition metals have exceptions to the expected filling order due to increased stability of half-filled or fully-filled d subshells.

Electron Orbital Stability and Exceptions to Electron Configurations

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