Multiple Choice
How many unpaired electrons are present in a ground-state vanadium (V) atom?
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10. Periodic Properties of the Elements
Valence Electrons of Elements
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What is the valence electron configuration for the magnesium atom?
A
3s^2
B
4s^2
C
3p^2
D
2s^2 2p^6
Verified step by step guidance1
Identify the atomic number of magnesium, which is 12. This tells us magnesium has 12 electrons in its neutral state.
Recall the order of filling electron orbitals according to the Aufbau principle: 1s, 2s, 2p, 3s, 3p, 4s, and so on.
Write the full electron configuration for magnesium by filling orbitals in order until all 12 electrons are placed: 1s^2 2s^2 2p^6 3s^2.
Determine the valence electrons by identifying the electrons in the outermost shell (highest principal quantum number n). For magnesium, the outermost shell is n=3, which contains the 3s^2 electrons.
Conclude that the valence electron configuration for magnesium is $3s^2$, since these are the electrons involved in chemical bonding and reactivity.
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