Multiple Choice
Which of the following electron configurations represents an atom of sulfur (atomic number 16) in an excited state?
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 phosphorus (atomic number 15) using core notation?
A
[Ne] 3s2 3p3
B
[Ar] 3s2 3p3
C
[He] 2s2 2p6 3s2 3p3
D
[Ne] 3s2 3p5
Verified step by step guidance1
Identify the atomic number of phosphorus, which is 15. This means phosphorus has 15 electrons to arrange in its electron configuration.
Recall that core notation uses the electron configuration of the nearest noble gas with fewer electrons as a shorthand to represent the inner (core) electrons.
Determine the noble gas preceding phosphorus in the periodic table. Since phosphorus has 15 electrons, the noble gas with 10 electrons before it is neon (Ne), whose electron configuration is 1s2 2s2 2p6.
Write the electron configuration of phosphorus by starting with the core notation [Ne], then add the remaining electrons in the outer shells. After neon's 10 electrons, phosphorus has 5 more electrons to place, which go into the 3s and 3p orbitals: 3s2 3p3.
Verify that the total number of electrons adds up to 15 and that the configuration follows the Aufbau principle, Hund's rule, and Pauli exclusion principle.
Related Videos
Related Practice
The Electron Configuration practice set
Problem sets built by lead tutorsExpert video explanations