Elements with one valence electron are generally more reactive than elements with two valence electrons due to their electron configuration and the concept of stability.
Valence electrons are the outermost electrons in an atom that participate in chemical bonding. They determine the chemical properties of an element, including its reactivity. Elements with one valence electron, such as Group 1 elements (alkali metals) like lithium (Li) and sodium (Na), have a configuration of one electron in their outermost energy level. These elements have a strong tendency to lose that single electron and achieve a stable, noble gas-like configuration.
On the other hand, elements with two valence electrons, such as Group 2 elements (alkaline earth metals) like beryllium (Be) and magnesium (Mg), have two electrons in their outermost energy level. While they can lose those electrons to achieve a stable configuration, it requires more energy compared to elements with one valence electron.
The reactivity of elements is related to the ease with which they can gain or lose electrons to form chemical bonds. Elements with one valence electron have a lower ionization energy (the energy required to remove an electron) because the electron is loosely held and farther away from the nucleus, making it easier to remove. This leads to a greater tendency to lose the electron and form positive ions.
In contrast, elements with two valence electrons have a higher ionization energy because these electrons are more strongly attracted to the nucleus due to the higher positive charge. Therefore, it requires more energy to remove these electrons, making the process less favorable and resulting in less reactivity compared to elements with one valence electron.
Additionally, elements with one valence electron also have a higher tendency to form stable, negative ions by gaining electrons from other atoms. This is because they only need to gain one electron to achieve a stable, noble gas electron configuration, while elements with two valence electrons would need to gain two electrons, which is energetically less favorable.
Overall, the reactivity of elements with one valence electron is higher than elements with two valence electrons due to the relative ease of losing or gaining electrons to achieve a stable electron configuration.