Question

(a) What are valence electrons? Where are valence electrons situated in an atom?
​(b) What is the number of valence electrons in the atoms of an element having atomic number 13? Name the valence shell of this atom.

Answer 1

(a) Valence electrons are electrons present in the outermost orbital of the atom. They basically represent the number of electrons which can participate in bond formation.
Valence electrons are present in the outermost orbit.

(b) Electronic configuration of the element with atomic number 13 is 2, 8, 3.
So, the valence electrons present in this element are 3.

$$\begin{gathered} 283 \\ KLM \end{gathered}$$

The valence shell of the atom will be M.