Answer:
Cs > Rb > K > Li
Explanation:
Given elements:
Li, Cs , K and Rb
Arrange in the the order of decreasing atomic radius:
Atomic radius is taken as half of the inter-nuclear distance (d) between two covalently bonded atoms of non - metallic elements or half of the distance between two nuclei in the solid state of metals.
- Across a periodic table, atomic radii decrease progressively from left to right.
- Down a group atomic radii increases progressively due to the successive shells of electrons being added.
So, the given species are the same group on the periodic table. These are group 1 elements;
Li, Cs , K and Rb
Cs > Rb > K > Li
