How many valence electrons does He have ?

Answer:

Helium has two valence electrons in its outermost shell. 

Explanation:

Here is the way on how to find the valence electron for He.

To find out the number of valence electrons in a He atom,we need to look at the periodic table.

He is an element of group 18.Now just consider the unit place digit from group number.You are getting 8 which should be equal to the number of valence electrons in helium.But 8 is not the number of valence electrons  for helium. By looking at the group number,you will not be able to find out the valence electrons of helium.

Here is the another way to find out the valence electrons of  He.

The atomic number of helium is 2.So it has two electrons totally.

Now write the electronic configuration of carbon.

He(2) =1s2

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 1.So,the valence shell is the 1st shell.

In 1st shell, we get two valence electron.So  each He has two valence electrons.

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