Problem 46 - Chemistry: An Atoms-Focused Approach

Question

Does the octet rule mean that a diatomic molecule must have 16 valence electrons?

Step-by-Step Solution

Answer

Answer: No, the octet rule does not imply that a diatomic molecule must have a total of 16 valence electrons. The octet rule refers to the tendency for atoms to achieve a stable electron configuration with eight valence electrons, but diatomic molecules can have different total numbers of valence electrons, as demonstrated by the examples of hydrogen (H2) and oxygen (O2).

Step 1: Understanding the Octet Rule

The octet rule states that atoms tend to gain, lose, or share electrons in such a way that they achieve a stable electron configuration with eight valence electrons. This stable configuration is like the electron configuration of the noble gases (except for helium, which has two valence electrons).

Step 2: Valence Electrons and Diatomic Molecules

Valence electrons are the outermost electrons in an atom that participate in chemical bonding. In a diatomic molecule, two atoms bond together by sharing, gaining, or losing valence electrons. The total number of valence electrons in a diatomic molecule is the sum of the valence electrons in each atom.

Step 3: Examples of Diatomic Molecules

Let's look at two common diatomic molecules: hydrogen (H2) and oxygen (O2). In hydrogen, each H atom has 1 valence electron. When two hydrogen atoms bond together to form H2, the molecule has a total of 1 + 1 = 2 valence electrons. In this case, the duet rule applies as they achieve a stable configuration with two electrons like helium. In oxygen, each O atom has 6 valence electrons. When two oxygen atoms bond to form O2, there are total of 6 + 6 = 12 valence electrons in the molecule, where each oxygen atom shares 2 electrons with the other atom, making the electron configuration resemble the stable configuration with 8 valence electrons.

Step 4: Conclusion

From the examples of hydrogen and oxygen, we see that diatomic molecules do not necessarily have 16 valence electrons. The octet rule refers to the tendency for atoms to achieve a stable electron configuration with eight valence electrons, but it does not imply that diatomic molecules must always have 16 valence electrons in total.