Question

14. Cesium (Cs) tends to be the most reactive of the alkali metals (francium is radioactive and has not been well studied). Based on your understanding of atomic radius, effective nuclear charge, and ionization energy, explain why this is true. 15. Time to Reflect…Consider everything you’ve learned in lab and lecture about periodic trends. In your own words, explain why it is important to know how the periodic table is organized. How do you think knowledge on periodic trends (ionization energy, electron affinity, atomic radius, electronegativity, etc.) help you, personally, in your future as scientist and/or engineer? 10. Explain how the reactivity with acid relates to the location of the metals on the periodic table.

Answer 1

As we go from top to bottom in a group number of valence electron will be same but the shell no will be continuesly increasing as a result effective nuclear charge will decrease and atomic radius will increase . Hence atomic radius of cesium is large as compare to other alkali metal except francium which correspond to less ionization energy ,i.e Cesium convert to Cesium ion more easily as compare to other alkali metal so its reactive will be higher as compare to other alkali metal.

Really it is important to know how the periodic table is organised because if we want to know the properties of some element and let all the element is in same group or same period then by knowing the properties of one element in a particular group or period we can know nearly properties of all the element because in a particular group or particular period element have almost similar properties .

In the periodic table as we go from top to bottom in a group atomic size increase so ionization energy decreases and electronegativity decreases and electron affinity also decreases and this all property changes in period ,i.e all revert in period as we go from left to right.