To construct the ground state electron configuration, QUESTION: Which of the following is the ground state electron configuration of Sulfur? A. 1s2 2s2 2p6 2d6 B. 1s2 2s2 2p6 3s2 3p4 C. 1s2 2s2 2p7 3s1 3p3 D. 1s2 2s2 2p6 3s2 3p6 To construct the ground state electron configuration, We first determine number of electrons We assign electrons to subshells following the Aufbau principle. Fill lowest energy subshells first. SCRIPT: Which of the following is the ground state electron configuration of a sulfur atom? One ess two, two ess 2, two pee six, two dee 6…. 1s2 2s2 2p6 3s2 3p4… 1s2 2s2 2p7 3s1 3p3 1s2 2s2 2p6 3s2 3p6 PAUSE CLICK TO construct the ground state electron configuration of an atom, we do the following CLICK First, we determine the number of electrons CLICK Then we assign electrons to subshells following the Aufbau principle. We fill the lowest energy subshells first. The best way to do these is to refer to the periodic table. Here’s sulfur…. We can see that it has an atomic number of sixteen. A sulfur atom has 16 electrons. Let’s assign these electrons. The first subshell is the 1s subshell. We can put a maximum of two electrons in an s subshell. The next subshell is the 2s subshell. CLICK The next two electrons are assigned to the 2s subshell. CLICK The next subshell is the 2p subshell CLICK Since a p subshell can accommodate a maximum of six electrons, we assign the next six electrons to the 2p subshell CLICK The next subshell is the 3s subshell CLICK We assign the next two electrons to this subshell. So far… we have assigned 12 electrons… We have four more to assign. CLICK These four will go into the the next subshell ---- the 3p subshell… CLICK Therefore, the ground state electron configuration of a sulfur atom is… 1s2 2s2 2p6 3s2 3p4 HIGHLIGHT configuration The correct answer is B. Note that choices A and C should immediately stand out as wrong. In choice A, six electrons are assigned to a 2d subshell. There is no 2d subshell. PUT X MARK on 2d6 In choice C, seven electrons are assigned to the 2p subshell. That exceeds that maximum allowed, which is six. Recall that Pauli’s principle says that the maximum number of electrons that can be assigned per orbital is 2. For a p subshell, there are 3 orbitals. 3 times 2 is 6 Finally, choice D is also wrong because the total number of electrons shown is 18, whereas a sulfur atom only has 16. CLICK PAUSE 2 seconds END RECORDING

1s 2p 2s 3s 3p S: 16 electrons 1s2 2s2 2p6 3s2 3p4

QUESTION: Which of the following is the ground state electron configuration of Sulfur? A. 1s2 2s2 2p6 2d6 B. 1s2 2s2 2p6 3s2 3p4 C. 1s2 2s2 2p7 3s1 3p3 D. 1s2 2s2 2p6 3s2 3p6 NOTE: Choices A and C should immediately stand out as wrong. There is no 2d subshell. Pauli’s principle forbids putting more than 6 electrons in a p subshell. Choice D has too many electrons (18); S has only 16 electrons. SCRIPT:

Video ID: 2-4-3 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08