Question

4.Why is the first ionization energy of a nonmetal much higher than that of an alkali metal in its same period? Provide an answer using 3 – 4 sentences in your own words.

Answer 1

1st ionization energy is the energy needed to loose one electron.

ionization energy depends on the attraction between the nucleus and the electron removed(this depends on the Nuclear charge and the atomic radii) and the stability of certain electronic configuration.

In group 1 alkali metals the atomic radii are very large relative to the nuclear charge. Hence the attraction of the outer most energy level to the nucleus is very less. Therefore the removal of 1st loosely bound electron is very easy . (shielding effect works on it )

when going from left to right across a period ( excluding the d block elements) the atomic radii decreases gradually . Though we expect a gradual decrease in the ionization energy across a period we get a zig zag pattern instead. But usually the non metals have a higher ionization energy as their radii are small thus the e/r ratio is high! it is hard to remove the electron.