. 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
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).