To achieve the noble gas configuration, alkali metals need to lose one electron (valence is one), whereas alkaline earth metals need to remove two. Elements in the same group share similar characteristics, like reactivity. However, as you go down the periodic table, there are more filled shells, so the valence electron are further away from the nucleus, and so are not as tightly held in, increasing the atomic radius. The periodic table organizes elements into groups and periods based on their chemical and physical properties. For example, a quick glance at Figure AT5.2. In the same group, the effective nuclear charge does not change. That way, we can get a better look at the relationship. Often it is useful to plot data on a graph. As a result, fluorine is usually thought of as the most electronegative element. The electron configuration of a oxygen atom is. While core electrons are not involved in bonding, they influence the chemical reactivity of an atom. However, on many scales, fluorine would be the most electronegative atom here. Generally, valence electrons can participate in the formation of chemical bonding, but core electrons cannot.
As a result, noble gases are also given electronegativity values on this scale.
The Allen scale just depends on the ability of an atom to interact with light, which is something even noble gases can do. Some electronegativity scales do not have values for the noble gases, because they are based on experimental measurements of compounds, and noble gases do not commonly form compounds with other elements. \): The Allen electronegativity values of the second-row elements.