Question

Carbon has an atomic number of 6, but the following orbital notation for carbon is incorrect. Explain the error in terms of the rules for electron arrangements.

Carbon:

1s is filled. 2s is filled. 2p is shown to contain two electrons in one orbital and no electrons in the other two orbitals.

Answer 1

The error in the orbital notation for carbon is that it does not follow Hund's rule, which states that electrons must occupy separate degenerate orbitals before pairing. The correct notation should show two 2p orbitals each with one electron, after the 1s and 2s orbitals are filled.

Step-by-step explanation:

The orbital notation presented for carbon, which shows two electrons in one of the 2p orbitals and none in the other two, is incorrect. The correct electron configuration following Hund's rule should have all the 2p orbitals singly occupied before any pairing of electrons occurs. This is because Hund's rule states that electrons will occupy separate orbitals of the same energy (degenerate orbitals) to maximize the number of unpaired electrons, which is the most stable arrangement due to electron repulsion.

Therefore, the correct electron configuration for carbon should be written as 1s² 2s² 2p¹ 11 11. The orbital diagram would show the 1s orbital filled with two electrons, the 2s orbital also filled with two electrons, and two 2p orbitals each with one electron, following the Pauli exclusion principle and Hund's rule.