# Stable oxidation state for Thallium and indium

The first Ionisation Enthalpy for Thallium is ~ 590 KJ/mol whereas that for Indium is ~ 558 kJ/mol. But why is +1 oxidation state more stable for Tlthan In? What are the other criteria that explain the stable +1 oxidation state of Thallium?

• What happens to $\ce{In+^1}$? How is it unstable? – Ivan Neretin Sep 5 '18 at 20:16
• In+1 readily oxidises to In+3 . – vaishnu suresh Sep 10 '18 at 8:53