A quantitative measure of the tendency of an element to lose electron is given by its ionization enthalpy. It represents the energy required to remove an electron from an isolated gaseous atom (X) in its ground state. In other words, the first ionization enthalpy for an element X is the enthalpy change `(Delta_(i)H)` for the reaction depicted.
`X(g) rarr X^(+) (g)+e^(-)`
The ionization enthalpy is expressed in units of `kJ mol^(-1)`. We can define the second ionization enthalpy as the energy required to remove the second most loosely bound electron: it is the energy required to carry out the reaction,
`X^(+)(g) rarr X^(2+)(g) +e^(-)`
Largest energy is required for which change?
A. `Sc_((g)) rarr Sc_((g))^(+)`
B. `Sc_((g))^(+) rarr Sc_((g))^(+2)`
C. `Sc_((g))^(+2) rarr Sc_((g))^(+3)`
D. `Sc_((g))^(+3) rarr Sc_((g))^(+4)`
