Multiple Choice
Which of the following orbital notations for phosphorus (atomic number 15) is correct?
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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 calcium (Ca)?
A
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2
B
1s^2 2s^2 2p^6 3s^2 3p^6 4p^2
C
1s^2 2s^2 2p^6 3s^2 3p^6 3d^10
D
1s^2 2s^2 2p^6 3s^2 3p^6 3d^2
Verified step by step guidance1
Step 1: Identify the atomic number of calcium (Ca), which is 20. This means calcium has 20 electrons to arrange in its electron configuration.
Step 2: Recall the order of filling electron orbitals based on the Aufbau principle: 1s, 2s, 2p, 3s, 3p, 4s, 3d, etc.
Step 3: Begin filling the orbitals with electrons following the order and the maximum number of electrons each orbital can hold: s orbitals hold 2 electrons, p orbitals hold 6, and d orbitals hold 10.
Step 4: Write the electron configuration by adding electrons in order until all 20 electrons are placed: 1s^2, 2s^2, 2p^6, 3s^2, 3p^6, and then 4s^2.
Step 5: Verify that the configuration matches the total number of electrons (20) and follows the correct filling order, confirming that the correct configuration is $1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6\ 4s^2$.
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