Question

Element:	K	Na	Rb	Cs	Li
Atomic radius (pm):	231	186	244	262	152

1. By referring to the modern periodic table find out the groups to which above the elements belong.
2. Arrange the above elements vertically downwards in an increasing order of atomic radii.
3. Does this arrangement match with the pattern of the group 1 of the modern periodic table?
4. Which of the above elements have the biggest and the smallest atom?
5. What is the periodic trend observed in the variation of atomic radii down a group?

Answer 1

1. The above elements belong to group 1.

2. The above elements arranged vertically downward in an increasing order of atomic radii:

Li	Na	K	Rb	Cs
152	186	231	244	262

3. In an increasing sequence of atomic radii, this arrangement corresponds to the pattern of group 1 of the current periodic table.

4. The biggest atom: Cs 
The smallest atom: Li

5. Atomic radius and atomic number both rise as the group decreases. As a result, atomic size progressively grows.