Question

A metal present in period III and group I of the periodic table is:
A.Lithium
B.Sodium
C.Potassium
D.Caesium

Answer 1

The periodic table has the arrangement of elements based on the increasing order of the atomic number and the group number designates the number of the valence shell electron and the period number designates the valence shell number or the principal quantum number.

Complete answer:
The elements present in group I are called the “alkali metals”. These metals include lithium in period 2, sodium in period 3, potassium in period 4, rubidium in period 5, Caesium in period 6, and Francium in period 7.

Hence, the metal present in period III and group I of the periodic table is “Sodium” which is option B.

Note:
As per the modern periodic law, “the properties of the elements are periodic functions of their atomic numbers'' hence the properties of the alkali metals are similar in nature, such as, the alkali metals are soft in nature and they can be cut by knife. These metals react very vigorously with water to form basic hydroxides and this reaction is highly exothermic. These metals have only one electron in their valence shell and so their group number is I and their valence is 1. These metals are called alkali metals due to the formation of alkalis as they react with water and where “alkalis'' refer to soluble bases. The alkali metals are highly electropositive in nature and they always have the tendency to lose electrons.