. The atomic radii of the elements of second period are given below

2nd period elements: B          Be        O         N         Li         F          C

Atomic radii (pm) :      88        111      66        74        152      64        77

i. Arrange these elements in the decreasing order of their atomic size

ii. Are the elements now arranged in the pattern of a period in the periodic table

iii. Which elements have the largest and the smallest atoms

iv. From this data, infer how the atomic size (or atomic radius) of the elements changes as you go from left to right in a period

v. Name one metal, one non-metal and one metalloid out of these elements

Ans:

i. In this given problem, the largest atomic radius 152 pm is of Li (Lithium), so Li should be placed first. This should be followed by Be (111 pm), B (88 pm), C (77 pm), N (74 pm), O (66 pm) and F (64 pm). We can now arrange the given elements in the decreasing order of their atomic radii as follows:

2nd period elements:       Li         Be        B          C         N         O         F

Atomic radii (pm):       152      111      88        77        74        66        64

ii. Yes, the elements are now arranged in the pattern of a period of periodic table

iii. The element Li (Lithium) has the largest atom (atomic radius 152 pm) whereas element F (Fluorine) has the smallest atom (atomic radius 64 pm).

iv. From the above arrangement of elements with their atomic radii, we find that the atomic radius (or atomic size) decreases on moving from left to right in a period of the periodic table.

v. Metal : Lithium (Li) ; Non-metal : Carbon (C) ; and Metalloid : Boron (B).