Q60 of 181 Page 306

In each of the following pairs, choose the atom having the bigger size:

(a) Mg (At. No. 12) or Cl( At. No. 17)


(b) Na (At. N0. 11) or K (At. No. 19)

(a) Mg is bigger in size because as we move left to right in period the atomic size decreases.

(b) K is bigger in size because as we move down the group the atomic size increases.


More from this chapter

All 181 →
58

An atom has the electron structure of 2, 7.

(a) What is the atomic number of this atoms?


(b) To which of the following would it be chemically similar?


7N, 15P, 17Cl, 18Ar


(c) Why would you expect it to be similar?

 59

Consider the following elements:

20Ca, 8O, 18Ar, 16S, 4Be, 2He


Which of the above elements would you expect to be:


(i) Very stable?


(ii) In group 2 of the periodic table?


(iii) In group 16 of the periodic table?

 61

The atomic numbers of three elements A, B and C are given below:


(i) Which element belongs to group 18?


(ii) Which element belongs to group 15?


(iii) Which element belongs to group 13?


(iv) To which period/periods do these elements belongs?

 62

An element X belongs to 3rd period and group 2 of the periodic table State:

(a) number of Valence electrons


(b) Valency


(c) metal or non-metal


(d) name of the element