Multiple Choice
Which of the following is the correct electron configuration for the element boron (B)?
4
views
10. Periodic Properties of the Elements
The Electron Configuration
Struggling with General Chemistry?
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 zirconium (Zr, atomic number 40)?
A
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 4d^4
B
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^4
C
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^2
D
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 5d^2
Verified step by step guidance1
Identify the atomic number of zirconium (Zr), which is 40. This means zirconium has 40 electrons to be placed in orbitals according to the Aufbau principle.
Recall the order of orbital filling based on increasing energy levels: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, and so on.
Fill the orbitals step-by-step with electrons, making sure to follow the Pauli exclusion principle and Hund's rule. For zirconium, after filling up to 4p^6 (which accounts for 36 electrons), the next electrons go into 5s and then 4d orbitals.
Recognize that the 5s orbital fills before the 4d orbital because 5s has lower energy than 4d. Therefore, the configuration will have 5s^2 before electrons start filling 4d orbitals.
Determine the number of electrons remaining after filling 5s^2 (which accounts for 2 electrons), and place the remaining electrons in the 4d orbital. For zirconium, this results in 4d^2.
Related Videos
Related Practice
The Electron Configuration practice set
Problem sets built by lead tutorsExpert video explanations