Vanadium, which has the atomic number 23, is located in group 5 of the periodic table. To determine the number of valence electrons, we look at the outermost shell of electrons. For vanadium, the electron configuration is [Ar] 3d3 4s2. This means that vanadium has 2 electrons in the 4s subshell and 3 electrons in the 3d subshell.
In the context of valence electrons, we consider only the electrons in the outermost shell. Therefore, adding the 4s and the 3d electrons together, we find that vanadium has a total of 5 valence electrons (2 from 4s and 3 from 3d). These valence electrons are significant because they are involved in forming chemical bonds and determining the chemical reactivity of the element.