Question 28: The increasing order of reactivity among group 1 elements is Li < Na < K < Rb CI > Br > I. Explain.
Answer:
These elements belongs to s block with general electronic configuration ns1 group 1 elements are called as alkali metals and are radioactive in nature.The elements present in group 1 have only 1 valence electron, which they tend to lose. Group 17 elements, on the other hand, need only one electron to attain the noble gas configuration. On moving down group 1, the ionization enthalpies decrease due to their very large atomic size, as a result of which the valence s electron can be readily removed .These values decrease down the group because of decrease in the magnitude of force of attraction with the nucleus on account of increased atomic radii and magnitude of screening effect. Thus, the increasing order of reactivity among group 1 elements is as follows:
Li < Na < K < Rb < Cs
They are called halogens (sea salt producers). In group 17, as we move down the group from Cl to I, the fluorine is the most reactive and iodine is least reactive because these halogens have low dissociation energies, as a result they easily dissociate into atoms and react with other substances. Also the halogens have high electron affinity and can easily gain an electron. Thus, the decreasing order of reactivity among group 17 elements is as follows:
F > Cl > Br > I
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