[sd79812]

"In half-filled subshell configurations, there is a maximum in the effective nuclear charge felt by the electrons (compared to the previous elements with no doubly-occupied orbitals) combined with relatively low interorbital repulsions due to the Pauli exclusion principle. "

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I don't see how this is right. I don't see how this answers the question on the periodic trend in melting/boiling point of transition metals.

The question was:

The melting and boiling points of transition elements increase from scandium (1530 ∘C
) to vanadium (1917 ∘C
). They increase because as we go across the group, we have more unpaired (free) electrons.

But at chromium (1890 ∘C
) however, the melting point decreases even though it has more unpaired electrons than the previous atoms. Why does this happen?

Is he/she suggesting that the elements in a row above some half-filled subshell configuration element who have less than half-filled valence shell has lower effective nuclear charge? But doesn't that ignore the fact that elements in the previous row have less shielding on their valence electrons so higher effective nuclear charge within a group?

https://chemistry.stackexchange.com/questions/4766/melting-and-boiling-points-of-transition-elements