s and d valence electrons

[Krupa Prajapati]

Hi! I was just wondering if when we have a transition metal, do the valence electrons come from the d block or the s block? Also, does the d orbital have lower energy than the s orbital? For example, in Iron, does 4s2 or 3d6 have higher energy? Thank you!

[Morgan Baxter 1E]

If you have a transition metal, the number of valence electrons you have will come from the s and d blocks depending upon how many electrons are lost. The 4s orbital has slightly lower energy than the 3d block. In iron, the 3d6 has higher energy than the 4s2. In Iron, the 4s2 electrons will be lost before the 3d6 electrons.