Question

Alkali metals are extremely reactive because they

a) easily lose one valence electron to become stable
b) easily gain one electron to become stable
c) easily lose one proton to become stable
d) have eight valence electrons, which is an unstable state

Answer 1

Alkali metals are extremely reactive because they have a single valence electron that they can easily lose to form a stable, singly positive ion. Their reactivity is tied to Group 1 elements having large atomic radii and low first ionization energies, facilitating the loss of the valence electron, especially as atomic number increases.The right answer is option A)

Step-by-step explanation:

Alkali metals are extremely reactive because they easily lose one valence electron to become stable. This characteristic is due to the fact that alkali metals, such as sodium and potassium, have a single s electron in their outermost subshell (an s¹ configuration). These elements belong to Group 1 of the periodic table and tend to form singly positive ions (e.g., Na⁺), by losing their loosely bound outermost electron.

The properties of alkali metals are similar to one another as they all have large atomic radii and the lowest first ionization energy in their periods. This makes it very easy to remove the single electron in the outermost (valence) shell, facilitating stable cation formation with a charge of 1+.

Overall, the reactivity increases with increasing atomic number in the group due to the ease of losing the lone valence electron, an effect which is attributed to the decreasing ionization energy for these elements.