state to which orbital does the last electron enter and why to the following elements:
1) 5d¹ 6s²
2) 4f¹ 5d¹ 6s¹
Answers
Answer:
please check the second configuration
Explanation:
the 1) The short answer is that it is the lowest energy configuration.
The longer answer is that at higher energy levels, starting even in the 3d — e.g. Cr has the configuration [Ar]4s1 3d5 rather than [Ar]4s2 3d4 — specific shielding effects cause there to be many irregularities to the Aufbau order of electron filling that many of us learned. The energy levels are so close together that even individual orbitals in a sublevel can have lower energies than a sublevel that should be lower in energy. Following along from La past Ce, Pr has the “expected” [Xe]6s2 4f3 configuration. Without knowing more about the specifics of the quantum mechanical descriptions of the attraction of specific orbitals to the nucleus (which is what ultimately determines the energy levels and, hence, the electron configuration), is it impossible to predict the ground state configurations through most of the d block and all of the f block. This would be a question that might be answered in a graduate level course.