Question

2. Consider the ionization energies of elements X and Y shown below in kJmol. X and Y are in the same period of the periodic table and are adjacent to one another in the table. 2nd 3rd 4th 5th th 117 1 8th 9th 1680 2080 33756050 8409 11022 15165 17868 3950612293701218015239 20000 92038106440 23068 115375 (a) in which group would one find element X? Explain. (b) Does element X lie to the right or the left of elementy in the periodic table? Explain. (c) Which is the first period on the periodic table that these elements could be in? Explain. (d) It is found that Y has the largest first ionization energy in the period that it is found. What does this tell us about Y? (e) It is found that element Q, which is in the same period as X and Y but lies to the left of element X in the periodic table, only has values for its first four ionization energies. Suggest a reason for this observation

Answer 1

The ionisation energy is defined as the amount of energy required to remove the most loosely electron from the ground state of an isolated gaseous atom. It is also called ionisation potential. The value of I. E is always positive. It increases along the periods and decreases along the groups. It is Maxima and minimum for Noble gas and alkali metal respectively. Half filled electronic configuration have higher ionisation energy than the next element along the period. For a given value of ' n ' the electron density near the nucleus deceases in the order s>p>d>f electron and the screening effect of electron also follow the same order.

(a) From the given data it seems that the element X has total nine I.E ( total electrons = 9) so it will belong to group 17 ( valance electron 7 i.e ns^{​​​ 2} np ⁵ )

(b) Element X is left to Y as per given data and above explanation.

(c) This is the first period where the two element belong which is supported by the given data.

(d) Largest ionisation energy means half filled or full filled electronic configuration. As Y belongs to right of X so it is in group 18