Question

What is the total number of electrons with quantum number l=0 for Be?
A. 2
B. 4
C. 3
D. 8

Answer 1

Hint: To answer this question, we should know about the value of l. We should know that the ℓ is known to be as second quantum number called Azimuthal Quantum Number.

Step by step answer:
Let us know about quantum numbers. We need to completely describe an electron in an atom, four quantum numbers are needed: energy (n), angular momentum (ℓ), magnetic moment (mℓ), and spin (ms). We should know that the first quantum number describes the electron shell, or energy level, of an atom. The value of n, ranges from 1 to the shell containing the outermost electron of that atom. Now, we will describe the azimuthal quantum number. We should know that second quantum number, known as the angular or orbital quantum number. We should know that ℓ = 0 is called an s orbital, ℓ = 1 a p orbital, ℓ = 2 a d orbital, and ℓ = 3 an f orbital. The value of ℓ ranges from 0 to n − 1 because the first p orbital (ℓ = 1) appears in the second electron shell.
So, now we will find the answer to this question. We should know that Be is called beryllium. As in the above paragraph we read that ℓ=0, for s orbital. And we should note that beryllium atomic number is 4. So, we should know that in s orbital there will be a maximum of two electrons. We can now say that, there will be two electrons with quantum number ℓ=0.
So, from the above discussion we can now say that option A is correct.

Note: We should know that quantum numbers are a set of numbers used to describe the position and energy of the electron in an atom. We should know that quantum numbers can be used to describe the trajectory and the movement of an electron in an atom. The quantum numbers of all the electrons in a given atom, when combined, must comply with the Schrodinger equation.