Question

(a) Choose the correct answer from the option: An element
in period 3 whose electron affinity is zero.
A. Neon B. Sulphur C. Sodium
D. Argon
(b) Give reason :
(i) Ionisation potential of the element increases
across a period from left to right. (2018)
(iii) Alkali metals are good reducing agents. (2018)
(c) There are three elements E, F, G with atomic numbers
19, 8 and 17 respectively –
Classifiy the above elements as metals and non-metals.
(d) Name : A metal present in period 3, group I of the
periodic table.​

Answer 1

Answer:

a. argon

b. i. As we move from left to right in a period, electrons are added to the same shell. ... Thus the outermost shell electrons come closer to the nucleus and are more firmly bound. Thus, more amount of energy is required to remove an electron from the outermost shell and hence, Ionisation Potential increases.

ii. Due to low ionization potential and having the smallest nuclear charge they can easily lose an electron. Hence, alkali metals are considered as a powerful reducing agent.

c. E has the atomic no. 19 . it has 1 valence electron. hence E is metal. similarly the F has 6 valence electrons and hence it is non metal. G has 7 valence electron hence it is non metal

d. sodium