Allowed values of principal quantum number (n): positive integers QUESTION: Which of the following are allowed values of the quantum numbers n and l, respectively ? A. 1.5 and 0, B. 3 and 3, C. 2 and 1, D. 0 and 1 Allowed values of principal quantum number (n): positive integers 1, 2, 3, … SCRIPT Which of the following are allowed values of the quantum numbers en and ell 1.5 and zero… 3 and 3… 2 and 1… Or 0 and 1 PAUSE 2 SECONDS Quantum numbers are numbers associated with atomic orbitals. They can only have certain allowed values CLICK In the case of the quantum number n,… which is called the principal quantum number…. HIGHLIGHT “principal quantum number” it can only be a positive integer…. In other words, the allowed values of en are 1, 2, 3, and so on…. Therefore we can eliminate choices A and D. In choice A, the first number given is 1.5, which is not an allowed value for en because it is not an integer. CLICK CLICK In choice D, the first number given is zero, which is not an allowed value for en…. En must be a positive integer. Zero is not a positive integer. As for the quantum number, ell…, which is called the orbital quantum number HIGHLIGHT “orbital quantum number” The allowed values are non-negative integers less than en…. In other words, integers starting from zero… up to en minus one… Let’s examine choice B. Here, en is equal to 3. Therefore… the allowed values for ell in this case are zero, 1, and 2. The number 3 is not an allowed value for ell in this case. Finally, let’s look at choice C. Here, en is equal to 2. Therefore… the allowed values of ell in this case are zero and one. Therefore, choice C is correct. END RECORDING Allowed values of orbital quantum number (l): non-negative integers less than n 0, 1, …, (n-1)

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