Question

why ceasium is more larger atomic radius than francium

Answer 1

Caesium with an atomic number of 55 has the largest ‘atomic radius’. Caesium has a large valence shell and a relatively low effective nuclear charge which means that the electrons can wander further away from the nucleus. Because of this, it is highly electropositive( it is very easy to remove the valence electron from Caesium) and hence very reactive. Nuclear charge increases as you go from left to right in the periodic table. By this logic, one could argue that Francium should have the largest atomic radius but Francium is radioactive and highly unstable and hence difficult to study. Also, it is impeded by this phenomenon called Lanthanide Contraction. Thus, the award goes to Caesium.

One of Caesium’s most important function is that is used as the basis for the atomic clock. Cesium is used to calculate the length of a second.