Write a Lewis structure for Br2 that obeys the octet rule
The correct answer and explanation is:
Correct Answer:
The Lewis structure for Br₂ (bromine molecule) is:
Br–Br
Each bromine atom has three lone pairs of electrons, and the two atoms share one pair (a single bond), making a total of eight electrons around each bromine atom, satisfying the octet rule.
Explanation (300 words):
The Lewis structure is a way to represent how atoms in a molecule share or transfer valence electrons to achieve full outer shells. For Br₂, the molecule consists of two bromine atoms. Each bromine atom has seven valence electrons because it is in Group 17 of the periodic table.
To satisfy the octet rule, which states that atoms tend to form bonds until they are surrounded by eight electrons, each bromine atom needs one more electron. The most straightforward way for two bromine atoms to achieve this is by sharing one pair of electrons in a single covalent bond. This shared pair of electrons counts toward the octet of both atoms.
So, one pair of electrons is placed between the two bromine atoms to form a single bond. Each bromine atom has six more valence electrons that are not shared. These are placed as three lone pairs (non-bonding pairs) around each bromine atom.
The structure looks like this:
Br:Br
Each bromine has three lone pairs around it, and the shared pair in the middle completes its octet. Thus, both atoms have eight electrons in their valence shells: six from the lone pairs and two from the shared bonding pair.
This structure is stable and obeys the octet rule. There are no formal charges, and the total number of electrons used (14) matches the total number of valence electrons available from the two bromine atoms (7 each). Therefore, this is the correct and complete Lewis structure for Br₂.