Chemical Bond Polarity Calculator

When two atoms bond to form a molecule, the electron(s) in the bond are not necessarily shared equally. By comparing the Electronegativity of the two atoms (See the Periodic Table for a list of Electronegativites), one can determine if the bond is Ionic (one atom takes the electron from the other atom in the bond), Polar Covalent (the electron is shared, but it is spends most of its time near the atom with higher electronegativity), or nonpolar covalent (the electron is shared between both atoms equally).

Notes on Electronegativity:

• Electronegativity is the ability of an atom within a molecule to pull electrons away from a binding partner (another atom in the molecule).
• Looking at the difference between the electronegativity of two bonded atoms
  • If the difference is > 2.0, the bond is ionic. For example, NaCl is an ionic bond, as Sodium (Na) has “given” its electron to Chlorine (Cl).
  • If the difference is between .4 and 2.0, the bond is polarized covalent (partly ionic). For example, in HCl, the bond is covalent, but the shared electron spends most of its time closer to the Cl atom than the H atom, forming a dipole
  • If the difference is less than .4, the bond is covalent, and the electron is shared equally. For example, Cl-Cl is a perfectly covalent bond since both partners have the same electronegativity
• Electronegativity increases as one travels within a Period from left to right in the Periodic Table.
• Electronegativity decreases as one traverses a group (column) from top to bottom in the Periodic Table.
• Francium (Fr) is the least electronegative element (we often say it is “electropositive”).
• Flourine (F) is the most electronegative element; in a molecule, it will try to pull the binding electrons from other atoms in the molecule towards itself.
• If two atoms have a large difference in electronegativites, a large amount of energy will be released upon forming the bond. If two atoms have a small difference in electronegativities, the energy released on formation of the bond will be small.