Question

What electron could have quantum numbers, n = 4,

Answer 1

The answer above is correct: C. A 4d electron

Answer 2

Answer:

Choice C.) A $4\, \rm d$ electron.

Explanation:

In an atom, each electron has a unique set of four quantum numbers.

$n$ is the principal quantum number. It gives the index of the energy shell that contains this electron. Hence, it must be a positive whole number (1, 2, 3, etc.) In this case, $n = 4$. Hence, this electron is in the fourth main energy shell. Think about this number as giving the size of the orbital that holds this electron.

$l$ is the orbital angular momentum quantum number. It gives the type (shape) of the orbital that holds this electron. $l$ should also be a whole number. However, unlike $n$, the value of $l$ starts from $0$ and has an upper bound, $(n - 1)$. Here are the meanings for some common values of $l$:

• $l = 0$ corresponds to an s-orbital. (Requires $n \ge 1$.)
• $l = 1$ corresponds to a p-orbital. (Requires $n \ge 2$.)
• $l = 2$ corresponds to a d-orbital. (Requires $n \ge 3$.)

As a side note, in each energy level, each type of orbital can hold more than one electrons. The other two quantum numbers, $m_l$ and $m_s$, help distinguish between these electrons. However, that's not very relevant to this problem.