Question
Question: How many electrons and orbitals are associated with \({\text{n}} = 4\)? A. \[32,64\] B. \[16,32\...
How many electrons and orbitals are associated with n=4?
A. 32,64
B. 16,32
C. 4,16
D. 8,16
Solution
Hint: Principal, azimuthal and magnetic quantum numbers are interconnected. Thereby we can calculate the total number of electrons and orbitals. These quantum numbers can be used to explain the energy of the electron in an atom.
Given data:
Principal quantum number, n=4
Complete step by step solution:
Atomic orbital is specified by four quantum numbers. They are used to describe the movement of electrons in atoms.
Principal quantum number n explains about the shell of the atom where ncan be 1,2,3 etc.
Azimuthal quantum number l , also called orbital angular momentum quantum number explains about the shape of the orbital. Also it depends upon the value of n . The value of llies between 0and n−1. It indicates the s, p, d, f subshell. If n=3, l can have values 0,1,2 i.e., it has s, p, d subshells.
Magnetic quantum number ml defines the total number of orbitals in a subshell and their orientation. It depends upon the l value. mlvalues range from −lto +l values. Total number of orbitals in a given subshell is given by 2l+1. Moreover, each orbital has two electrons.
Spin quantum number ms tells about the direction in which the electron spins and is independent of other quantum numbers.
Here n=4.
Therefore l can have values 0,1,2,3 i.e., s, p, d, f subshells.
For l=0,ml=2l+1=2×0+1=1values⇒0
For l=1,ml=2l+1=2×1+1=3values⇒−1,0,+1
For l=2,ml=2l+1=2×2+1=5values⇒−2,−1,0,+1,+2
For l=3,ml=2l+1=2×3+1=7values⇒−3,−2,−1,0,+1,+2,+3
Total number of orbitals is the total number of mlvalues.
i.e., 1+3+5+7=16orbitals.
Two electrons can be occupied in an orbital.
Therefore total number of electrons=2×16=32 electrons.
Hence option B is correct.
Additional information:
n=1denotes the innermost shell or the first shell which is near to the nucleus. When the value of nincreases, there will be a larger distance from the nucleus. Spin quantum number also describes whether a magnetic field can be produced by an atom or not.
Note: Magnetic quantum number depends on l value thereby can connect to nvalue. Two electrons of the same atom cannot have the same quantum state. This is Hund’s rule. Or it does not have the same quantum numbers.