Final answer:
Bonds are arranged from least to most polar as Cl-Cl (nonpolar), Br-Cl (slightly polar), and Cl-F (definitely polar), with Br and Cl acquiring a δ+ and F acquiring a δ- due to differences in electronegativity.
Step-by-step explanation:
To arrange the bonds in order of increasing polarity and indicate bond polarity with symbols, one must consider the electronegativity of the elements involved in each bond. Polarity increases with the absolute difference in electronegativity between two bonded atoms. The more electronegative atom acquires a δ- (delta minus) symbol, indicating a slight negative charge, while the less electronegative atom gets a δ+ (delta plus) symbol, indicating a slight positive charge.
In the given set of bonds (Cl-F, Br-Cl, Cl-Cl), here is the order of increasing polarity:
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- Cl-Cl — Nonpolar covalent, as both atoms have the same electronegativity, there is no charge difference between the atoms (both chlorine atoms are the same).
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- Br-Cl — Slightly polar covalent, bromine (Br) is less electronegative than chlorine (Cl), making Br δ+ and Cl δ-.
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- Cl-F — Definitely polar covalent, fluorine (F) being more electronegative than chlorine (Cl) results in F acquiring a δ- and Cl a δ+.
Electronegativity values are critical for determining the polarity of a bond, and the polarity refers to the separation of electric charges leading to a molecule or its chemical groups having an electric dipole moment.