Multiple Choice
Which of the following is the correct electron configuration for selenium (Se)?
3
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 magnesium (Mg)?
A
1s^2 2s^2 2p^6 3s^2
B
1s^2 2s^2 2p^6 3p^2
C
1s^2 2s^2 2p^6 3d^2
D
1s^2 2s^2 2p^6 3s^1
Verified step by step guidance1
Step 1: Identify the atomic number of magnesium (Mg), which tells you the total number of electrons. Magnesium has an atomic number of 12, so it has 12 electrons.
Step 2: Recall the order in which electron orbitals are filled according to the Aufbau principle: 1s, 2s, 2p, 3s, 3p, 4s, 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), etc.
Step 4: Distribute the 12 electrons of magnesium into the orbitals: 2 electrons in 1s, 2 in 2s, 6 in 2p, and the remaining 2 in 3s.
Step 5: Write the electron configuration by listing the orbitals and their electron counts in order: $1s^2 2s^2 2p^6 3s^2$.
Related Videos
Related Practice
The Electron Configuration practice set
Problem sets built by lead tutorsExpert video explanations