What are ‘groups’ and ‘periods’ in the ‘periodic table’? (b) Two elements M and N belong to groups I and II respectively and are in the same period of the periodic table. How do the following properties of M and N vary? 1. Sizes of their atoms

Question

(a) What are ‘groups’ and ‘periods’ in the ‘periodic table’?

(b) Two elements M and N belong to groups I and II respectively and are in the same period of the periodic table.

How do the following properties of M and N vary?

1. Sizes of their atoms

2. Their metallic characters

3. Their valencies in forming oxides

4. Molecular formulae of their chlorides

 · Answer

(a) The vertical columns in the periodic table are called ‘groups’. The horizontal rows in the periodic table are called ‘periods’.

(b)

‘M’ and ‘N’ belong to same period but group I and II. Therefore, ‘N’ will be smaller than ‘M’ as atomic size goes on decreasing from left to right.
‘M’ is more metallic than ‘N’. Metallic character goes on decreasing from left to right as tendency to lose electrons decreases due to decrease in atomic size.
Their valences are 1 and 2 respectively in forming oxides. Valency goes on increasing first and then decreases.
MCI, NCl₂ are molecular formulae of their chlorides.

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