How many valence electrons are present in the atom with the following electron configuration 1s2 2s2 2p6 3s2 3p5?

Answer:

The element with the electron configuration of 1s2 2s2 2p6 3s2 3p5 has seven valence electrons.But it has totally 17 electrons.

Explanation:

Given, 1s2 2s2 2p6 3s2 3p5

At first,find out the Valence shell.Here, the third shell is the valence shell 3s23p5.We know that the electrons in valence shell are called valence electrons.Here we get seven valence electrons in 3s23p5.That is why the element with the electron configuration of 1s2 2s2 2p6 3s2 3p5 has seven valence electrons.