# Which of the following is not a valid set of four quantum numbers? How can you determine this?

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a. 2,0,0, + 1/2

b. 2,1,0, -1/2

c. 3,1, -1, -1/2

d. 1,0,0, +1/2

e. 1,1,0, +1/2?

a. 2,0,0, + 1/2

b. 2,1,0, -1/2

c. 3,1, -1, -1/2

d. 1,0,0, +1/2

e. 1,1,0, +1/2?

##### 1 Answer

The answer is

#### Explanation:

Start by making sure that you're familiar with the valid values each quantum number can take.

As you can see, the *principal quantum number*, *angular momentum quantum number*, *magnetic quantum number*,

The *spin quantum number* is independent of the of the values taken by the other three quantum numbers and can only have two possible values,

Now, take a look at the relationship between the value of

This set is valid because

This quantum number set represents an electron located on the **second energy level**, in the **s-subshell**, in the **orbital**, that has spin-up.

This set is valid because

#l = 0, 1, ..., (n-1)#

when **second energy level**, in the **p-subshell**, in the **orbital**, that has spin-down.

Once again, you're dealing with a valid set. All the quantum numbers are well within their accepted values. Notice that when

#m_l = {-1, color(white)(-)0, +1}#

This set represents an electron located on the **third energy level**, in the **p-subshell**, in the **orbital**, that has spin-down.

This set is valid and it represents an electron located on the **first energy level**, in the **s-subshell**, in the **orbital**, that has spin-up.

This is **not** a valid set of quantum numbers. Notice that

#n=1" "# and#" "l=1#

This means that the set cannot describe an electron located in an atom, i.e. it's **not a valid set**.