Question

XI) answer the following
26. The atomic radii of second group elements are given below
B
Elements B. Be. O. N. Li. C

Atomic. 88 111. 66. 74 152. 77
radius5

a}Arrange them in the decreasing order of their atomic size.
b}Name the elements whichhave the smallest and largest atoms.
c}How does the valency vary when moving from left to right in a period and as you go down in a
group?
​

Answer 1

Answer:

a)66,74,77,88,111,152

Answer 2

Answer:

Li

152

Be

111

B

88

C

77

N

74

O

66

F

64

(b) Yes, the elements are now arranged in the pattern of a

period of periodic table.

(c)

(i)F has the largest atomic number

(ii)Li has the smallest atomic number

(b) Atomic radius decreases on moving from left to right in a

period of the periodic table.

(c) Metal:- Li; Non-metal:- C; Metalloid:- B

(d) Atomic radius decreases from left to right in a period because force of attraction for the outermost electrons towards nucleus increases because of increased nucl

charge.