Question

Element:	O	B	C	N	Be	Li
Atomic radius (pm):	66	88	77	74	111	152

1. By referring to the modern periodic table find out the periods to which the above elements belong.
2. Arrange the above elements in a decreasing order of their atomic radii.
3. Does this arrangement match with the pattern of the second period 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 radius while going from left to right within a period?

Answer 1

1. The above elements belong to period 2.

2. The above elements are arranged in a decreasing order of their atomic radii:

Li	Be	B	C	N	O
152	111	88	77	74	66

3. Yes, this specific arrangement perfectly matches the horizontal sequence of the second period. Moving from left to right across the row, the elements naturally appear in the exact order of Li, Be, B, C, N, and O.

4. The biggest atom: Lithium (Li) 
The smallest atom: Oxygen (O)

5. Atomic radius falls, and atomic number increases as one moves from left to right in a period. As a result, atoms get smaller over time.