Multiple Choice
Which of the following is the correct electron configuration for krypton (Kr)?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following orbital notations for phosphorus (atomic number 15) is correct?
A
1s^2 2s^2 2p^6 3s^2 3p^6
B
1s^2 2s^2 2p^6 3s^2 3p^3
C
1s^2 2s^2 2p^6 3s^2 3p^1
D
1s^2 2s^2 2p^6 3s^2 3p^5
Verified step by step guidance1
Step 1: Identify the atomic number of phosphorus, which is 15. This means phosphorus has 15 electrons to be placed in orbitals according to the Aufbau principle.
Step 2: Recall the order of filling orbitals: 1s, 2s, 2p, 3s, then 3p. Each orbital can hold a specific number of electrons: s orbitals hold 2, p orbitals hold 6.
Step 3: Fill the orbitals in order until all 15 electrons are assigned: 1s holds 2 electrons, 2s holds 2 electrons, 2p holds 6 electrons, 3s holds 2 electrons, and the remaining electrons go into 3p orbitals.
Step 4: Calculate the number of electrons in the 3p orbital by subtracting the electrons already assigned (2 + 2 + 6 + 2 = 12) from 15, which gives 3 electrons in 3p.
Step 5: Write the correct electron configuration as $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{3}$, matching the number of electrons in each orbital to the total of 15.
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