Which elements are not main-group elements?(a) Al(b) Br(c) Mo(d) Cs(e) Pb

Solution 56P

Step 1:

Here, we have to determine which among the given elements are not main-group elements.

The main group elements consist of the first two columns (the hydrogen and beryllium columns) and the last six columns (the boron through helium columns). That is the elements found in groups 1, 2 and 13 to 18 are main group elements. 

In these elements, S- and p- electrons fill in a regular repeating manner. Hence, elements in the s- and p-blocks have predictable patterns that represent a wide range of properties. Therefore, the s- and p-block elements are called the main-group or representative elements.

The main group elements in the periodic table are shown below :