Explanation of Discrepancy in Reducing Power of Alkali Metals

Variation in Reducing Power:
- The reducing power of alkali metals is determined by their ability to donate electrons, with larger atoms having more easily ionizable electrons.
- The trend of reducing power among alkali metals is generally expected to increase from left to right in the periodic table.

Factors Contributing to Discrepancy:
- The discrepancy in the reducing power trend of alkali metals can be attributed to various factors such as atomic size and ionization energy.
- In the case of lithium (Li), even though it is the smallest alkali metal, it has the highest ionization energy due to its strong nuclear charge. This makes it less likely to donate electrons compared to other larger alkali metals.
- On the other hand, cesium (Cs) is the largest alkali metal with the lowest ionization energy, making it the most easily ionizable and therefore the best reducing agent among alkali metals.

Effect of Atomic Size and Ionization Energy:
- The discrepancy in reducing power can be explained by the balance between atomic size and ionization energy. While larger atoms have more easily ionizable electrons, they also have more electron shells which can shield the outermost electron from the nucleus, reducing the overall reducing power.
- The smaller size of lithium results in a higher ionization energy, making it less effective as a reducing agent compared to larger alkali metals like cesium.

Overall Trend:
- Despite the discrepancy in the reducing power trend, the general trend of reducing power among alkali metals still follows the expected pattern of increasing from left to right in the periodic table. The specific characteristics of each alkali metal, such as atomic size and ionization energy, contribute to the observed differences in their reducing power.