1E.10

[Jorja De Jesus 2C]

Of the following sets of four quantum numbers {n,l,ml,ms}, identify the ones that are forbidden for an electron in an atom and explain why they are invalid.
(a) {2,2,-1,+1/2}; (b) {6,6,0,+1/2}; (c) {5,4,+5,+1/2}

[Brittney Hun 2C]

You need to use the definition of the quantum numbers to describe the location and spin of an atom. The d sub shell in c (described by l=2) can only hold a total of 5 orbitals, so c is not a valid set of numbers since the absolute value of the magnetic quantum number cannot exceed the value of the angular momentum quantum number l.

[Ryan Yee 1J]

Quantum numbers are as follows: n can be any integer as a principle electron shell, it cannot be 0; l is the angular momentum quantum number, it can take any values from 0 to (n-1); ml is the magnetic quantum number and can take any number between -l and +l; lastly ms is the electron spin quantum number and is either +1/2 or -1/2. Following these rules, A and B are forbidden because their l value is the same as n, when the maximum l value could only be either 0 or 1 in the case of A or 0, 1, 2, 3, 4, or 5 in the case of B. C is also forbidden because, ml can only take values from -l to +l, so a value of +5 exceeds the highest value of +4 set by l in this set of numbers.