Question

Which of the following best helps to explain why Na(s) is more reactive with water than Mg(s) is? Group of answer choices:

The first ionization energy of Na is less than that of Mg.
The Na+ ion has weaker Coulombic attraction to an anion than the Mg2+ ion has.
The atomic mass of Na is less than that of Mg.
Na(s) is softer than Mg(s).

Answer 1

Na(s) is more reactive with water than Mg(s) because sodium has a lower first ionization energy, which allows its valence electron to be removed more easily facilitating a more vigorous reaction.

Step-by-step explanation:

The reactivity of sodium (Na) with water compared to magnesium (Mg) can best be explained by the first ionization energy of the two elements. Sodium has a lower first ionization energy than magnesium, which means it requires less energy to remove its outermost electron. This property is attributed to sodium's larger atomic radius, which allows for its outer electron to be more easily removed than magnesium's, contributing to sodium's higher reactivity in water. Furthermore, sodium forms Na+ with a single positive charge, whereas magnesium forms Mg2+ with a double positive charge. The energy required to remove two electrons from magnesium to form this ion is significantly higher than that for sodium, making the sodium reaction with water more vigorous.