How many valence electrons does Sr have?
Answer:
Sr has two valence electrons.
To find out the number of valence electrons in a Sr atom,we need to look at the periodic table.
The position of Sr in the periodic table is in group IIA.For main group elements,valence electrons are equal to the group number.So,Sr atom has two valence electrons in its valence shell or outermost energy level.
Again, Sr is an element of group 2.Now just consider the unit place digit from group number.You are getting 2 which is equal to the number of valence electrons in Sr.
Here is the another way to find out the valence electrons of Sr.
The symbol of strontium is Sr and the atomic number of Sr is 38.So,it has thirty eight electrons totally.
Now write the electronic configuration of Sr.
Sr(38) =1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2
=[Kr] 5s2
[Tip: Complete filled d orbital is not considered as part of valence shell or energy level]
The valence shell is the outermost shell and the electrons that are present in valence shell is called valence electrons.
The valence shell or energy level can be identified by the highest value of principal quantum number,n.Here the highest value of n is 5.So,the valence shell is the 5th shell or energy level.
In 5th shell ,we get two valence electrons.So each Sr has two valence electrons.
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