According to the n plus l rule, which orbital is filled first?
Correct answer: B. 4s
- A. 3d
- B. 4s
- C. 4p
- D. 4d
Explanation
For 4s the sum is 4 plus 0, that is 4, while for 3d it is 3 plus 2, that is 5, so the lower sum fills first and 4s is occupied before 3d. When two orbitals have the same sum, the one with the lower n fills first. This ordering explains why potassium and calcium come before the transition metals.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? support@testustad.com
About Electronic Configuration
Electronic configuration describes how electrons occupy shells, subshells and orbitals around an atom. Questions use the Aufbau principle, Pauli exclusion principle and Hund's rule to write configurations, identify valence electrons, form ions and explain periodic trends, including common exceptions such as chromium and copper.
Practise Atomic Structure
922 free Atomic Structure MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Chemistry questions like this
Chemistry is on 14 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Electronic Configuration questions
The Pauli exclusion principle states that
Hund's rule states that within a subshell, electrons
Which orbital is filled immediately after the 4s orbital according to the Aufbau principle?
The electronic configuration of the chloride ion, given that chlorine has atomic number 17, is
Chromium and copper have anomalous electronic configurations because
The energy required to remove the most loosely bound electron from a gaseous atom is called