1. Count Valence Electrons:
* Bromine (Br) has 7 valence electrons.
* Oxygen (O) has 6 valence electrons, and there are 3 oxygen atoms.
* The -1 charge adds one more electron.
Total valence electrons: 7 + (3 * 6) + 1 = 26
2. Determine the Central Atom:
* Bromine (Br) is less electronegative than oxygen, so it will be the central atom.
3. Connect Atoms with Single Bonds:
* Place the three oxygen atoms around the bromine atom, connecting them with single bonds.
4. Distribute Remaining Electrons:
* Each single bond uses 2 electrons, so we've used 6 electrons so far (3 bonds * 2 electrons/bond).
* We have 20 electrons remaining (26 - 6).
* Place lone pairs on each oxygen atom to complete their octets (6 electrons each), using 18 electrons.
* This leaves 2 electrons remaining.
5. Place Remaining Electrons on Central Atom:
* Place the remaining 2 electrons on the bromine atom as a lone pair.
6. Check for Formal Charges:
* The formal charge on each oxygen atom is 0.
* The formal charge on the bromine atom is +1 (7 valence electrons - 6 nonbonding electrons - 1 bond).
* The overall charge of the ion is -1, as expected.
Lewis Dot Structure:
```
..
:O:
|
Br
/ \
:O: :O:
..
```
Important Note: The bromine atom has expanded its octet to accommodate more than 8 electrons. This is possible for elements in period 3 and below.
