Textbook Question
The following electron configurations represent excited states. Identify the element and write its ground-state condensed electron configuration. (b) 3Ar44s13d104p25p1
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10. Periodic Properties of the Elements
The Electron Configuration: Condensed
Multiple Choice
Which of the following is the correct condensed electron configuration for selenium (Z = 34)?
A
[Kr] 5s2 4d10 5p4
B
[Ne] 3s2 3p6 4s2 3d10 4p4
C
[Ar] 4s2 3d10 4p4
D
[Ar] 4s2 3d10 4p6
Verified step by step guidance1
Step 1: Identify the atomic number of selenium, which is 34. This means selenium has 34 electrons to be placed in orbitals according to the Aufbau principle.
Step 2: Recall the order of filling orbitals: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, and so on. Use this to build the electron configuration step by step.
Step 3: Recognize that noble gas shorthand notation uses the electron configuration of the previous noble gas to simplify the configuration. For selenium, the previous noble gas is krypton (Kr, Z=36) or argon (Ar, Z=18), depending on how far you want to condense.
Step 4: Write the condensed electron configuration starting from the noble gas core. For selenium, the correct noble gas core is [Ar], which accounts for the first 18 electrons. Then add the remaining electrons in the 4s, 3d, and 4p orbitals.
Step 5: Confirm the total number of electrons adds up to 34 by summing the electrons in the noble gas core plus the electrons in the outer orbitals: [Ar] 4s\^2 3d\^10 4p\^4.
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