Multiple Choice
Which of the following lists the three fundamental rules used to write the electron configuration of elements?
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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 sodium (Na)?
A
1s^2 2s^2 2p^6 3s^2
B
1s^2 2s^2 2p^6
C
1s^2 2s^2 2p^5 3s^2
D
1s^2 2s^2 2p^6 3s^1
Verified step by step guidance1
Step 1: Identify the atomic number of sodium (Na), which tells you the total number of electrons. Sodium has an atomic number of 11, so it has 11 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 maximum capacity of each: 1s can hold 2 electrons, 2s can hold 2 electrons, 2p can hold 6 electrons, and 3s can hold 2 electrons.
Step 4: Distribute the 11 electrons into these orbitals in order: 2 electrons in 1s, 2 electrons in 2s, 6 electrons in 2p, and the remaining 1 electron in 3s.
Step 5: Write the electron configuration by listing the orbitals and their electron counts: $1s^2 2s^2 2p^6 3s^1$, which matches the correct configuration for sodium.
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