Multiple Choice
Which of the following is the correct electron configuration for magnesium (atomic number 12)?
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10. Periodic Properties of the Elements
The Electron Configuration
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Consider the following electron configurations. Which atom is expected to be the most stable?A) 1s^2 2s^2 2p^6B) 1s^2 2s^2 2p^5C) 1s^2 2s^2 2p^4D) 1s^2 2s^2 2p^3
A
C) 1s^2 2s^2 2p^4
B
D) 1s^2 2s^2 2p^3
C
B) 1s^2 2s^2 2p^5
D
A) 1s^2 2s^2 2p^6
Verified step by step guidance1
Identify the electron configurations given and recognize that they correspond to elements in the second period of the periodic table, specifically filling the 2p subshell with varying numbers of electrons.
Recall that atoms tend to be most stable when their electron shells are fully filled or half-filled due to electron configuration stability principles, such as the octet rule and exchange energy.
Analyze each configuration: A) 1s^2 2s^2 2p^6 represents a completely filled 2p subshell (6 electrons), B) 1s^2 2s^2 2p^5 is one electron short of full, C) 1s^2 2s^2 2p^4 has two electrons less than full, and D) 1s^2 2s^2 2p^3 is half-filled in the 2p subshell.
Understand that a fully filled subshell (like in A) is generally more stable than partially filled or half-filled subshells because it minimizes electron-electron repulsions and maximizes symmetry.
Conclude that the configuration with the fully filled 2p subshell (A) is expected to be the most stable atom among the options.
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