text: Therefore , elements with the same number of valence electrons are grouped together in the periodic table of the elements .
simplified: Elements which have eight valence electrons ( noble gases ) are inert and they do not tend to create chemical reactions with other elements in the Periodic table group . The number of valence electrons is also important for determining the group of an element in the Periodic table , because an element 's number of valence electron is the same as the number of its group in the periodic table .