Valence electrons are the number of electrons present in the outermost energy shells. The number of the valence electrons present in an element is reflected by its position in the periodic table. In a given period number of electrons in a valence shell increases from left to right. Whereas in a group, the number of valence electrons remains the same from top to bottom. Right most group of elements i.e group no. 18, noble gas elements will therefore have the maximum number of valence electrons.