Multiple Choice
Which of the following electron configurations is impossible?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following species has the electron configuration 1s^2 2s^2 2p^6 3s^2 3p^6?
A
Ar
B
K^+
C
Na^+
D
Cl^-
Verified step by step guidance1
Identify the total number of electrons in each species to determine their electron configurations.
Recall that the electron configuration 1s^2 2s^2 2p^6 3s^2 3p^6 corresponds to a total of 18 electrons, which is the electron configuration of the noble gas Argon (Ar).
Calculate the number of electrons for each species: K^+ (potassium ion) has 19 - 1 = 18 electrons, Na^+ (sodium ion) has 11 - 1 = 10 electrons, and Cl^- (chloride ion) has 17 + 1 = 18 electrons.
Compare the electron counts to the configuration: species with 18 electrons will have the configuration 1s^2 2s^2 2p^6 3s^2 3p^6.
Conclude that both K^+ and Cl^- have this electron configuration, but since the question asks for the species with this configuration, Ar (neutral argon) naturally has it, and among the ions, K^+ and Cl^- also match this configuration due to their electron count.
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