Multiple Choice
What is the ground-state electron configuration of boron (B, atomic number 5)?
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9. Electrons in Atoms and the Periodic Table
The Electron Configuration (Simplified)
Multiple Choice
In noble-gas shorthand notation, what is the ground-state electron configuration of rubidium (Rb, atomic number 37)?
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Verified step by step guidance1
Identify the atomic number of rubidium (Rb), which is 37. This tells us rubidium has 37 electrons in its neutral ground state.
Recall that noble-gas shorthand notation uses the electron configuration of the nearest noble gas with a lower atomic number as a starting point. Find the noble gas with atomic number less than 37, which is krypton (Kr) with atomic number 36.
Write the electron configuration of krypton (Kr) in brackets: \([\mathrm{Kr}]\). This represents the first 36 electrons.
Determine the electron configuration for the 37th electron, which will be placed in the next available orbital after krypton. Since rubidium is in group 1 of the periodic table, the next electron goes into the 5s orbital.
Combine the noble gas core with the additional electron: \([\mathrm{Kr}]\,5s^{1}\). This is the ground-state electron configuration of rubidium in noble-gas shorthand notation.
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