InterviewSolution
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InterviewSolution
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Teacher explained periodictiy of ionisation potential in a period and group with reasons. She then drew a curve of IP vs. atomic numeber for elements with Z = 11 to Z = 20.On the basis of the curve, she asked the following questions to students. (a) Identify the elements occupying peaks and bottom-most points.(b) Also identify 'X', and 'Y' marked in the curve. (c) In what respect 'X' and 'Y' deviat from their preceeding elements? ltbegt When students answered these correctly, she was satisfied and told - "Now, I will give you a brain teaser to get me answer by next chemistry class" . Students enthusiastically said - "yes"! Then teacher wrote the following question on board __ (d)" Why do "X" and "Y" show deviations from their preceeding elements in the trend of IP velues"? What explanation would you give if you were there in the class? |
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Answer» Solution :(a) Peak is occupied by noble gas, Ar. Bottom-most point is occupied by alkali metal, K. (b) 'X' is aluminium and 'Y' is sulphur. (c) Generally, with increase in atomic number, IP value should also increase. However, from MAGNESIUM to aluminium, IP value decreases. Similariy, from PHOSPHORUS to sulphur, IP value decreases. (d) In magnesium, there is a pair of electrons in 3s orbital. REMOVAL of electron is slightly more difficult. Morepver, since the electron to be removed belongs to 's' subshell having greater penetrating power, the IP value is relatively HIGHER. In case of aluminium, there is an unpaired 'p' electron, whose removal is easier. Hence, IP value is less. |
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