Why is the oxygen atom listed first in \(\mathrm{OF}_{2}\) but last in \(\mathrm{Br}_{2} \mathrm{O} ?\)

Electronegativity is a measure of how strongly an atom attracts the electrons in a bond towards itself. In chemical formulas, the element with the higher electronegativity is usually written first. This is important when writing the formula as it affects the order of the elements in the compound.

To determine the order of the elements in the chemical formulas, we need to find out the electronegativities of oxygen (O), fluorine (F), and bromine (Br). The values are as follows: - Oxygen: electronegativity value of 3.44 - Fluorine: electronegativity value of 3.98 - Bromine: electronegativity value of 2.96

In the compound \(\mathrm{OF}_{2}\), we compare the electronegativity values of oxygen and fluorine: - Oxygen: 3.44 - Fluorine: 3.98 Fluorine has a higher electronegativity value compared to oxygen. Despite this, oxygen is placed first in the formula. This is because oxygen is the central atom in the compound, and fluorine atoms are bonded to the oxygen atom. In such binary compounds, the element with the lower electronegativity (oxygen in this case) is placed first, irrespective of their electronegativity values.

In the compound \(\mathrm{Br}_{2} \mathrm{O}\), we compare the electronegativity values of oxygen and bromine: - Oxygen: 3.44 - Bromine: 2.96 Oxygen has a higher electronegativity value compared to bromine. Thus, according to the rules for writing chemical formulas, the oxygen atom should be written last in the chemical formula, resulting in \(\mathrm{Br}_{2} \mathrm{O}\). In conclusion, the oxygen atom is listed first in \(\mathrm{OF}_{2}\) due to oxygen being the central atom and chlorine atoms being bonded to it, despite having a lower electronegativity value than fluorine. In contrast, oxygen is listed last in \(\mathrm{Br}_{2} \mathrm{O}\) as it has a higher electronegativity value than bromine, following the rules for writing chemical formulas.