Why the second ionization enthalpy is greater than the first ionization enthalpy?

What is ionization enthalpy?

Enthalpy is equal to

How would you explain the fact that the first ionization enthalpy of sodium is lower than that of magnesium but its second ionization enthalpy is higher than that of magnesium?

Define: Enthalpy of ionization

What are the trends in:- ionization enthalpy of group 17 elements ?

Among the second period elements the actual ionization enthalpies are in the order Li Explain why O has lower Delta_iH than N and F ?

Among the second period elements the actual ionization enthalpies are in the order Li Explain why Be has higher Delta_iH than B

Amongst the following, select the element having highest ionization enthalpy