Multiple Choice
How many unpaired electrons are present in a neutral beryllium (Be) atom?
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10. Periodic Properties of the Elements
The Electron Configuration
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Which of the following is the correct electron configuration for aluminum (Al)?
A
1s^2 2s^2 2p^6 3s^2 3p^2
B
1s^2 2s^2 2p^6 3s^1 3p^2
C
1s^2 2s^2 2p^6 3s^2 3p^1
D
1s^2 2s^2 2p^6 3s^2 3p^3
Verified step by step guidance1
Step 1: Determine the atomic number of aluminum (Al), which tells you the total number of electrons. Aluminum has an atomic number of 13, so it has 13 electrons.
Step 2: Recall the order in which electron orbitals are filled according to the Aufbau principle: 1s, 2s, 2p, 3s, 3p, and so on.
Step 3: Fill the orbitals with electrons following the order and the maximum number of electrons each orbital can hold: 1s (2 electrons), 2s (2 electrons), 2p (6 electrons), 3s (2 electrons), and 3p (6 electrons).
Step 4: Assign the 13 electrons to the orbitals in order: 1s^2, 2s^2, 2p^6, 3s^2, and then place the remaining electron(s) in the 3p orbital.
Step 5: Write the electron configuration by combining the filled orbitals with their electron counts, ensuring the total adds up to 13 electrons.
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