Question

write the valency of :-
1. alkali metal
2. alkaline earth metals
3. halogens
4. zero group elements

Answer 1

Answer:

1. valency of all alkali metals contains 1 electron though the number of energy shells are different. their general electronic configuration is ns^1,where ,n is the number of valence shell.
2. Alkaline earth metals belong to 2nd group of modern periodic table. They have 2 electrons in their outermost valence shell. As it's easy for them to lose 2 electrons than gain 6 more electrons to achieve octet, they lose electrons and acquire a charge of +2. Valency of alkaline earth metal is often misunderstood as 6, no, it's +2.
3. Valency lavel of the elements in the halogen group is one. Halogens belong to group `17 of periodic table and their general electronic configuration is ns² np ⁵. So, they have a tendency to accept one electron to get noble gas configuration.
4. Group 18.  Valency is defined as the measure of the combining power with other atoms when it forms a molecule of compound.

          Valency of metals = number of electrons lost

           Valency of non-metals = Number of electrons gained.

 Noble gases have valency 0 because these elements cannot loose                or gain electrons. The electrons are fully filled in the sub-shells of these elements. hence, the valency of these elements is 0. These elements belong to the last group of periodic table which is Group 18.