Which of the following best explains why Group 1 elements (alkali metals) are highly reactive?

• A. They have strong metallic bonds that prevent them from reacting with other substances.
• B. They have a single valence electron that is easily lost, resulting in a stable noble gas configuration.
• C. They have high ionization energies, making it difficult to lose electrons.
• D. They have completely filled valence shells, making them unstable.

Answer: (B)

Verified step by step guidance

1. Understand the electronic configuration of Group 1 elements (alkali metals). These elements have one electron in their outermost shell, known as the valence electron.
2. Recall that chemical reactivity in metals often depends on how easily they can lose electrons to achieve a stable electron configuration, typically that of the nearest noble gas.
3. Recognize that alkali metals have relatively low ionization energies, meaning it requires little energy to remove their single valence electron.
4. Removing this valence electron allows the atom to attain a full, stable electron shell configuration similar to that of noble gases, which is energetically favorable.
5. Therefore, the high reactivity of Group 1 elements is best explained by their tendency to lose this single valence electron easily, leading to a stable noble gas electron configuration.