Can the following groups of elements

Question:

Can the following groups of elements be classified as Dobereiner’s triad ?

(a) Na, Si, Cl

(b) Be, Mg, Ca

Solution:

Atomic mass of Be = 9; Na = 23; Mg = 24; Si = 28; Cl = 35; Ca = 40 Explain by giving reason.

(a) No, these elements cannot be classified as triads because these do not have same properties. However, the atomic mass of Si (28) is almost

the mean of the atomic masses of elements Na (23) and Cl (35).

Note : The Dobereiner’s triad is meaningful only if the elements present in the triad have almost identical properties.

(b) Yes, these elements can be classified as triads. These belong to the same group (2) and have almost identical properties. The atomic mass of

Mg (24) is almost the mean of the atomic masses of the elements Be (9) and Ca(40) i.e., 9 + 40 = 49/2 = 24.5.

Leave a comment

Close
faculty

Click here to get exam-ready with eSaral

For making your preparation journey smoother of JEE, NEET and Class 8 to 10, grab our app now.

Download Now