Question

In each of the following groups, which element is least reactive? a. Group 1 b. Group 7 c. Group 2 d. Group 6

Short answer

The least reactive elements in each group are: a. Hydrogen (H) in Group 1, b. Astatine (At) in Group 7, c. Beryllium (Be) in Group 2, and d. Polonium (Po) in Group 6.

Step-by-step solution

Examine Group 1

Group 1 elements are known as alkali metals. As we move down in Group 1, the atomic size increases, and the ionization energy decreases, making it easier for electrons to be lost. The least reactive element is the one with the highest ionization energy, which is the element at the top of the group.

Examine Group 7

Group 7 elements are known as halogens. The reactivity of halogens generally decreases moving down Group 7, as atomic size increases and electronegativity decreases. The least reactive element is the one further down the group, with the lowest electronegativity.

Examine Group 2

Group 2 elements are known as alkaline earth metals. Similar to Group 1, the reactivity of these elements generally increases moving down Group 2. The least reactive element is the one with the highest ionization energy, which is the element at the top of the group.

Examine Group 6

Group 6 elements are known as chalcogens. For nonmetals like those in Group 6, generally reactivity decreases moving down the group, as atomic size increases and electronegativity decreases. The least reactive element is the one further down the group, with the lowest electronegativity.

Identify the least reactive elements

a. In Group 1, the least reactive element is hydrogen (H) due to its highest ionization energy. b. In Group 7, the least reactive element is astatine (At) due to its lowest electronegativity. c. In Group 2, the least reactive element is beryllium (Be) due to its highest ionization energy. d. In Group 6, the least reactive element is polonium (Po) due to its lowest electronegativity.