1. A d subshell consists of 5 orbitals.
QUESTION:
For which of these are all the occupied d subshells completely filled? A. Sc, B. Zr, C. Mn, D. Cd
A d subshell consists of 5 orbitals.
Pauli’s Exclusion Principle: max. 2 electrons/orbital
Completely filled d subshell has 10 electrons
Sc 1s2 2s2 2p6 3s2 3p6 4s2 3d1
Zr s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d2
Mn 1s2 2s2 2p6 3s2 3p6 4s2 3d5
Cd 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10
SCRIPT:
For which of these are all the occupied d subshells completely filled?
Scandium… zirconium… manganese… or cadmium
PAUSE
CLICK A d subshell consists of five orbitals.
CLICK
Pauli’s exclusion principle says that a maximum of two electrons can be assigned to each orbital
Therefore, a d subshell is completely filled if it has 10 electrons. 5 times 2 equals 10.
To answer this question, let’s write the ground state electron configuration for these atoms.
For Scandium, this is the electron configuration
CLICK The only d orbital that is occupied is the 3d orbital, but it has only one electron.
HIGHLIGHT 3d1
Therefore, the 3d subshell is not completely filled.
For Zirconium, this is the electron configuration
CLICK Two d subshells are occupied ---- the 3d and the 4d.
The 3d subshell is completely filled with 10 electrons.
HIGHLIGHT 3d10
But the 4d subshell only has 2 electrons.
HIGHLIGHT 4d2
For Manganese, this is the electron configuration
CLICK Here we have a half-filled 3d subshell.
HIGHLIGHT 3d5
Finally, for cadmium, this is the electron configuration
CLICK Here, we can see that two d subshells are occupied --- the 3d and the 4d.
And both of these subshells are completely filled.
HIGHLIGHT 3d10 and 4d10
The correct answer is D…. cadmium.
We could have easily determined the answer to this question by referring to the periodic table.
Notice that all of these elements are transition metals. The last entry in the electron configuration is a d subshell,
HIGHLIGHT 3d1, 4d2, 3d5, and 4d10
following a completely filled valence s subshell.
HIGHLIGHT 4s2, 5s2, 4s2, and 5s2
This is characteristic of all transition metals. That is why the transition metals are also said to belong the d block.
CLICK TO SHOW PERIODIC TABLE
CLICK TO SHOW D BLOCK
When we write the electron configurations of transition metals, we find that the last entry for elements in group three B, or column 3, is d1.
CLICK Recall that the last entry for scandium is 3d1
For column 4, which includes zirconium, it’s d2
CLICK For column 5, it’s d3
CLICK For column 6, it’s d4
For column 7, which includes manganese, it’s d5
CLICK For column 8, it’s d6
For column 9, it’s d7
For column 10, it’s d8
CLICK For column 11, it’s d9
And for column 12, it’s d10.
IN other words, elements in column 12 have completely filled d subshells.
You can see that Cadmium belongs in this column.
One final note… there are exceptions to the generalizations made here…
In some cases, an electron is shifted from the valence s subshell into the d orbital.
Notable exceptions are chromium, copper, niobium, molybdenum, ruthenium, and rhodium
CLICK PAUSE
END RECORDING

2. d1 d2 d3 d4 d5 d6 d7 d8 d9
d10
The “d block”

3. The correct answer is D…. cadmium.
EXCEPTIONS:
Cr 4s1 3d5
Cu 4s1 3d10
Nb 5s1 4d4
Mo 5s1 4d5
Ru 5s1 4d7
Rh 5s1 4d8
More exceptions at:
SCRIPT:
Which of the following does not have a partially filled d subshell?
Scandium… zirconium… manganese… or cadmium
PAUSE
CLICK A d subshell consists of five orbitals.
CLICK
Pauli’s exclusion principle says that a maximum of two electrons can be assigned to each orbital
Therefore, a d subshell is completely filled if it has 10 electrons. 5 times 2 equals 10.
To answer this question, let’s write the ground state electron configuration for these atoms.
For Scandium, this is the electron configuration
CLICK The only d orbital that is occupied is the 3d orbital, but it has only one electron.
HIGHLIGHT 3d1
Therefore, the 3d subshell is not completely filled.
For Zirconium, this is the electron configuration
CLICK Two d subshells are occupied ---- the 3d and the 4d.
The 3d subshell is completely filled with 10 electrons.
HIGHLIGHT 3d10
But the 4d subshell only has 2 electrons.
HIGHLIGHT 4d2
For Manganese, this is the electron configuration
CLICK Here we have a half-filled 3d subshell.
HIGHLIGHT 3d5
Finally, for cadmium, this is the electron configuration
CLICK Here, we can see that two d subshells are occupied --- the 3d and the 4d.
And both of these subshells are completely filled.
HIGHLIGHT 3d10 and 4d10
The correct answer is D…. cadmium.
We could have easily determined the answer to this question by referring to the periodic table.
Notice that all of these elements are transition metals. The last entry in the electron configuration is a d subshell,
HIGHLIGHT 3d1, 4d2, 3d5, and 4d10
following a completely filled valence s subshell.
HIGHLIGHT 4s2, 5s2, 4s2, and 5s2
This is characteristic of all transition metals. That is why the transition metals are also said to belong the d block.
CLICK TO SHOW PERIODIC TABLE
CLICK TO SHOW D BLOCK
When we write the electron configurations of transition metals, we find that the last entry for elements in group three B, or column 3, is d1.
CLICK Recall that the last entry for scandium is 3d1
For column 4, which includes zirconium, it’s d2
CLICK For column 5, it’s d3
CLICK For column 6, it’s d4
For column 7, which includes manganese, it’s d5
CLICK For column 8, it’s d6
For column 9, it’s d7
For column 10, it’s d8
CLICK For column 11, it’s d9
And for column 12, it’s d10.
IN other words, elements in column 12 have completely filled d subshells.
You can see that Cadmium belongs in this column.
CLICK PAUSE
END RECORDING

4. Video ID: © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08