Multiple Choice
What is the ground-state electron configuration of silicon (Si), atomic number ?
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9. Electrons in Atoms and the Periodic Table
The Electron Configuration (Simplified)
Multiple Choice
In the simplified electron configuration (noble-gas shorthand), what is the electron configuration of phosphorus (P)?
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Verified step by step guidance1
Identify the atomic number of phosphorus (P), which is 15. This tells us phosphorus has 15 electrons to arrange in its electron configuration.
Recall the noble gas that comes before phosphorus in the periodic table. Neon (Ne) has an atomic number of 10, so its electron configuration can be used as the shorthand starting point.
Write the noble-gas shorthand configuration starting with [Ne], which represents the first 10 electrons: \(\[Ne\]\).
Determine the remaining electrons to place after neon. Since phosphorus has 15 electrons total, subtract the 10 electrons in neon, leaving 5 electrons to be placed in the 3s and 3p orbitals.
Fill the 3s and 3p orbitals with these 5 electrons following the Aufbau principle: 2 electrons fill the 3s orbital, and the remaining 3 electrons go into the 3p orbital, resulting in the configuration \(\[Ne\] 3s^{2} 3p^{3}\).
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