Multiple Choice
Which noble-gas symbol is used in the noble-gas notation for the electron configuration of tin (Sn)?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following is the correct electron configuration for the sodium ion, Na$^+$?
A
1s^2 2s^2 2p^6 3s^1
B
1s^2 2s^2 2p^6
C
1s^2 2s^2 2p^5
D
1s^2 2s^2 2p^6 3s^2
Verified step by step guidance1
Recall that the electron configuration describes the distribution of electrons in an atom's orbitals, following the Aufbau principle, Hund's rule, and the Pauli exclusion principle.
Determine the number of electrons in a neutral sodium (Na) atom. Sodium has an atomic number of 11, so it has 11 electrons.
Write the electron configuration for neutral sodium: $1s^2 2s^2 2p^6 3s^1$, which accounts for all 11 electrons.
Since the problem asks for the electron configuration of the sodium ion, Na$^+$, recognize that it has lost one electron compared to the neutral atom, so it has 10 electrons.
Remove one electron from the highest energy orbital (the 3s orbital) of the neutral sodium configuration to get the electron configuration of Na$^+$: $1s^2 2s^2 2p^6$.
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