The reactivity of an element is influenced by various factors, including the number of valence electrons, their energy level, and the atomic structure. While both erbium and magnesium have two valence electrons, their reactivity differs significantly due to other factors.
Atomic Size: Erbium is an element in the lanthanide series, which is known for having larger atomic radii compared to the elements in the s-block, such as magnesium. The larger size of erbium atoms results in weaker attraction between the valence electrons and the nucleus, making it less likely to lose or gain electrons compared to magnesium.
Ionization Energy: The ionization energy refers to the energy required to remove an electron from an atom. In the case of magnesium, the removal of its two valence electrons requires relatively low energy due to its smaller atomic size and stronger nuclear attraction. This makes magnesium more likely to undergo ionization and become reactive. Conversely, erbium has higher ionization energies due to its larger size and weaker nuclear attraction, making it less likely to lose its valence electrons and exhibit reactivity.
Electronegativity: Electronegativity is a measure of an atom's tendency to attract electrons towards itself. Magnesium has a lower electronegativity compared to erbium, indicating that magnesium is more likely to lose its valence electrons and exhibit reactivity. Erbium's higher electronegativity makes it less likely to readily lose electrons and participate in chemical reactions.
Overall, the differences in atomic size, ionization energy, and electronegativity contribute to the contrasting reactivity of magnesium and erbium, despite both having two valence electrons. The unique electronic configuration and position in the periodic table of each element play a crucial role in determining their reactivity.