Answer:

B has three valence electrons.

Explanation:

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

The position of B in the periodic table is in group IIIA.For main group elements,valence electrons are equal to the group number.So,B atom has three valence electrons in its valence shell.

Boron is an element of group 13.Now just consider the unit place digit from group number.You are getting 3 which is equal to the number of valence electrons in B.

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

The symbol of boron is B and the atomic number of boron is 5.So, it has five electrons totally.

Now do the electronic configuration of boron.

B(5) =1s2 2s2 2p1

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 2.So,the valence shell is the 2nd shell.

In 2nd shell we get 3 valence electrons.So each B has 3 valence electrons.

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