Given: The Lewis structure of BeCl
.
The structure shown above is an exception to the octet rule because the arrangement _
gives beryllium only four electrons.
does not contain any double bonds.
contains only two chlorine atoms.
gives each chlorine atom only eight electrons.
contains a beryllium atom.
The Correct Answer and Explanation is:
The correct answer is “gives beryllium only four electrons.”
Explanation
The octet rule states that atoms tend to form bonds until they are surrounded by eight valence electrons, achieving a stable configuration similar to noble gases. However, certain elements like beryllium can be exceptions due to their unique electron configurations and bonding tendencies.
In the Lewis structure of beryllium chloride, beryllium is centrally bonded to two chlorine atoms through single covalent bonds. Each chlorine atom contributes one electron to the bond, and since beryllium only has two valence electrons to share, it ends up with four electrons in its valence shell instead of the usual eight. This deviation makes it an exception to the octet rule.
Unlike other elements that strictly adhere to the octet rule by forming additional bonds or acquiring lone pairs, beryllium frequently forms stable compounds with fewer than eight valence electrons. This occurs because beryllium is a small atom with a relatively low tendency to attract additional electrons. In compounds like BeCl₂, beryllium achieves a stable electronic state by forming two single bonds with chlorine without completing an octet.
The other answer choices do not correctly explain why BeCl₂ is an exception. The absence of double bonds is not directly related to the octet rule, the presence of two chlorine atoms is simply a structural feature, each chlorine atom correctly follows the octet rule, and the mere inclusion of beryllium does not explain why the compound is an exception. Therefore, the defining reason is that beryllium has only four valence electrons, making BeCl₂ an exception to the octet rule
