Question

9. Consider the following list of orbitals in the hydrogen atom:

3p 3d     4f     5s 5p

Which of these orbitals is highest in energy in the hydrogen atom?

3p is highest in energy

3d is highest in energy

4f is highest in energy

5p is highest in energy

5s and 5p are equal in energy, and are both highest in energy

10.

Neodymium, atomic number 60, is a metal that is used in making very strong permanent magnets. Consider the following orbitals in the ground-state neodymium atom:

3p 3d     4f     5s 5p

Which of these orbitals is highest in energy in the neodymium atom?

3p

3d

4f

5p

5s and 5p are equal in energy, and are both highest in energy I believe it is 4f. Am I correct?

Answer 1

In case of multi electron system, (n+1) rule determines the energy of electrons. Here, 'n' is principle quantum number and 'l' is angular quantum number. The energy of electron increases with increase in (n+1) value. In case of one electron system (hydrogen atom), energy of electron is determined by principle quantum number 'n' only. The energy of electron increases with increase in 'n value. (a) For hydrogen atom, the energy of electrons in different subshell but having same 'n' value is same. The value of 'n' for 5s and 5p orbital is 5. The value of 'n' for 5s and 5p is more as compared to others. Therefore, 5s and 5p orbital are equal in energy, and are both highest in energy. (b) In this case, Neodymium is multielectron system. Therefore, (n+1) rule determines the energy of electrons. Calculate 'n' and 'l' value for the given orbitals as follows:

Orbitals Зр 3d 4f 5p n-value l-value 31 32 4 3 5 | 1 Calculate (n+1) value for the given orbitals as follows: (n+1) value Orbitals 3p 3d 4f 5p 5 Higher is (n+1) value, higher is energy of orbital. Therefore, 4f orbital has the highest energy in the neodymium atom.