Q61 of 181 Page 306

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?

(i) Element C belongs to group 10 because it has 8 elements in the last shell and its valency is 0.

(ii) elements belongs to group 15 because it has 5 electrons in its last shell.


(iii) an element belongs to the group 13 because it has 3 electron in its valence shell.


(iv) These elements belong to the 2nd period because all the 2 shells are filled.


More from this chapter

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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?

 60

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)

 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

 63

The following diagram shows a part of the periodic table in which the elements are arranged according to their atomic numbers. (The letters given here are not the chemical symbols of the elements):


(i) Which element has a bigger atom, a or f?


(ii) Which element has a higher valency, k or o?


(iii) Which element is more metallic, i or k?


(iv) Which element is more non-metallic, d or g?


(v) Select a letter which represents a metal of valency 2.


(vi) Select a letter which represents a non-metal of valency 2.