Question

The iconic compounds that result from combining group 2 and group 16 elements have a 1:1 ratio because:

A. Group 2 elements have a valency of +2, and group 16 elements have a valency of -2, creating a balanced charge.
B. It is a fundamental law of chemistry that all compounds must have a 1:1 ratio.
C. Group 2 elements are twice as reactive as group 16 elements.
D. It is purely coincidental, and there is no specific reason for the 1:1 ratio.

Answer 1

Ionic compounds between group 2 and group 16 elements have a 1:1 ratio because group 2 elements lose two electrons to form a 2+ cation, while group 16 elements gain two electrons to form a 2- anion, balancing the charge and satisfying the octet rule.

Step-by-step explanation:

The iconic compounds that result from combining group 2 and group 16 elements have a 1:1 ratio because Group 2 elements have a valency of +2, and group 16 elements have a valency of -2, creating a balanced charge. Each alkaline earth metal (group 2) atom loses two electrons to form a 2+ cation, and each chalcogen (group 16) gains two electrons to form a 2- anion. The transfer of electrons is such that the total number of electrons lost by the alkaline earth metals is equal to the number of electrons gained by the chalcogens, resulting in a compound that is electrically neutral. For example, when magnesium from group 2 combines with oxygen from group 16, the product is magnesium oxide, MgO, which satisfies the octet rule for both magnesium and oxygen atoms, leading to a stable 1:1 compound. This is also an illustration of the law of conservation of matter which requires that the total number of electrons lost must be equal to the number of electrons gained in a chemical reaction.