Periodicproperties show aregular gradation onmovingfrom leftto rightin aperiodor fromtoptobottomin a group . Downa groupthe atomicionicradii, metalliccharacterand reducing characterincreasewhileionizationenthalpyand electronegativitydecrease. Alonga periodfrom leftto rightatomic ionicradiiand metalliccharacterdecrease whileionizationenthalpyelectronegativitynon- metalliccharacterand oxidisingpowerincreases. However ,electrongainenthalpybecomesless negativedown agroupbut morenegativealonga period. Incontrastinertgaseshavepositiveelectrongainenthalpies whichdo not showanyregular trend .Whichof the followingisoelectronicions has thelowestfirst ionizationenthalpy ?

Periodicproperties show aregular gradation onmovingfrom leftto rightin

1.	Periodicproperties show aregular gradation onmovingfrom leftto rightin aperiodor fromtoptobottomin a group . Downa groupthe atomicionicradii, metalliccharacterand reducing characterincreasewhileionizationenthalpyand electronegativitydecrease. Alonga periodfrom leftto rightatomic ionicradiiand metalliccharacterdecrease whileionizationenthalpyelectronegativitynon- metalliccharacterand oxidisingpowerincreases. However ,electrongainenthalpybecomesless negativedown agroupbut morenegativealonga period. Incontrastinertgaseshavepositiveelectrongainenthalpies whichdo not showanyregular trend .Whichof the followingisoelectronicions has thelowestfirst ionizationenthalpy ?
Answer» `K^(+)` `Ca^(2+)` `C1^(-)` `S^(2-)` SOLUTION :biggerthe SIZE`(s^(2-))` smallerthe `Delta_(i)H_(1)`