Multiple Choice
Using the periodic table, which of the following is the correct electron configuration for selenium (Se)?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which element has the ground state electron configuration 1s^2 2s^2 2p^6 3s^2 3p^6 4s^1?
A
Magnesium (Mg)
B
Sodium (Na)
C
Calcium (Ca)
D
Potassium (K)
Verified step by step guidance1
Identify the electron configuration given: $1s^2 2s^2 2p^6 3s^2 3p^6 4s^1$.
Count the total number of electrons by adding the superscripts: $2 + 2 + 6 + 2 + 6 + 1$.
Recall that the number of electrons in a neutral atom equals the atomic number of the element.
Match the total number of electrons to the element with that atomic number on the periodic table.
Recognize that the configuration ends with $4s^1$, which corresponds to the first element in the fourth period with one electron in the 4s subshell, identifying the element as Potassium (K).
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