Why is enthalpy of atomization of Mn exceptionally low? Transition elements usually have high values, especially so for greater number of unpaired electrons. Why the exception here?
According to "Atomic Structure and Periodicity" by Jack Barrett, the reason is a combination of the $d^5$ electron configuration (half filled subshell) in the gas state and, relative to chromium, "the extra electron in the metal occupying an anti-bonding region of a band, s or d".