Dear beloved readers, welcome to our website! We hope your visit here brings you valuable insights and meaningful inspiration. Thank you for taking the time to stop by and explore the content we've prepared for you.
------------------------------------------------ Why should the 4s subshell be filled before the 3d subshell?

A. The 4s subshell has greater spherical symmetry than the 3d subshell.
B. The 4s subshell is farther from the nucleus than the 3d subshell.
C. The 4s subshell is at a lower energy level than the 3d subshell.
D. The 4s subshell holds fewer electrons than the 3d subshell.

In the electron configuration of atoms, electrons occupy subshells in order of increasing energy. The 4s subshell has greater spherical symmetry and is farther from the nucleus, but it is still at a lower energy level than the 3d subshell.

This is known as the Aufbau principle, which guides the arrangement of electrons in atomic orbitals. Even though the 4s subshell holds fewer electrons compared to the 3d subshell, the energy difference is the deciding factor for filling up the 4s subshell first.

Learn more about Aufbau principle at

https://brainly.com/question/19221869

#SPJ11

qwarrow qwarrow · Answer 2 · 2023-12-28T19:14:31-05:00

Final answer:

The 4s subshell is filled before the 3d subshell because it is lower in energy once the 3p subshell is filled, as reflected in both the electronic configurations of the elements and the structure of the periodic table.

Explanation:

The reason 4s subshell is filled before the 3d subshell has everything to do with the energy levels of the subshells. Electrons will occupy the subshell that is lower in energy first, and as it turns out, the 4s subshell is at a lower energy than the 3d subshell once the 3p subshell is filled. This filling order is reflected in both the structure of the periodic table as well as the electronic configurations of the elements. For example, after argon (Ar), with a filled 3p subshell, potassium (K) follows with an electron configuration of 1s²2s²2p⁶3s²3p⁶4s¹, indicating that the next electron enters the 4s subshell.

An additional reason for this order is that electrons in the s subshell have probability clouds that penetrate closer to the nucleus, which means they are more tightly bound and thus lower in energy as compared to the d subshells. This penetration causes the 4s to have a lower energy than the 3d when it comes to filling them with electrons. It's also worth noting that each subshell has a specific number of orbitals, and these orbitals have distinctive shapes and orientations that affect their energy levels.