What’s the electron configurations of scandium and iodine using aufbau principle?me

I think the electron configuration of an atomic species neutral or ionic allows us to understand the shape and energy of its electrons. Many general rules are taken into consideration when assigning the "location" of the electron to its prospective energy state, however these assignments are arbitrary and it is always uncertain as to which electron is being described. Knowing the electron configuration of a species gives us a better understanding of its bonding ability, magnetism and other chemical properties. i hope this helps

They can measure  the amount of energy gained or lost