Q

# Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?

8.3     Explain briefly how $+2$ state becomes more and more stable in the first half of the first row transition elements  with increasing atomic number?

According to our observation, except scandium, all other elements of the first row shows +2 oxidation state. On moving from Sc to Mn the atomic number increases from 21 to 25 and also the increasing number of electrons in 3d orbitals from $d^{1} - d^{5}$. when metals lose two electrons from its 4s orbital then they achieve +2 oxidation state. Since the number of d electrons in (+2) state increases from $Ti(+2) - Mn(+2)$ , the stability of the +2 oxidation state increases as d-orbitals is becoming more and more half filled.
Mn(+2) has $d^{5}$ configuration, which is half filled (it makes it highly stable)