Multiple Choice
What is the ground-state electron configuration of the fluoride ion, F⁻?
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10. Periodic Properties of the Elements
The Electron Configuration: Ions
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Which of the following is the correct electron configuration for the Mg^{2+} ion?
A
1s^2 2s^2 2p^4
B
1s^2 2s^2 2p^6 3s^1
C
1s^2 2s^2 2p^6
D
1s^2 2s^2 2p^6 3s^2
Verified step by step guidance1
Step 1: Identify the atomic number of magnesium (Mg), which is 12. This means a neutral Mg atom has 12 electrons.
Step 2: Understand that the Mg^{2+} ion has lost 2 electrons, so it has 12 - 2 = 10 electrons.
Step 3: Write the electron configuration for 10 electrons, which corresponds to the electron configuration of neon (Ne), the noble gas before Mg.
Step 4: Recall the order of filling orbitals: 1s, 2s, 2p, 3s, etc. For 10 electrons, the configuration fills up to 2p orbitals completely.
Step 5: Conclude that the correct electron configuration for Mg^{2+} is \$1s^2 2s^2 2p^6$, since the 3s electrons are removed when forming the ion.
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