The ability of one atom in a molecule to attract shared electrons is dubbed electronegativity. When two atom combine, the difference between their electronegativities is one indication of the form of bond that will certainly form. If the difference in between the electronegativities that the two atoms is small, no atom can take the mutual electrons completely away from the various other atom and the bond will be covalent. If the difference in between the electronegativities is large, the much more electronegative atom will take the bonding electrons fully away from the various other atom (electron move will occur) and the bond will certainly be ionic. This is why steels (low electronegativities) bonded with nonmetals (high electronegativities) generally produce ionic compounds.

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A bond may be for this reason polar that an electron in reality transfers from one atom come another, forming a true ionic bond. Just how do we judge the level of polarity? Scientists have actually devised a scale referred to as electronegativity, a range for judging how much atom of any element attract electrons. Electronegativity is a unitless number; the higher the number, the an ext an atom attractive electrons. A usual scale because that electronegativity is displayed in figure \\(\\PageIndex1\\).

api/deki/files/78265/CK12_Screenshot_9-13-3.png?revision=1&size=bestfit&width=320&height=311\" />Figure \\(\\PageIndex2\\) A nonpolar covalent bond is one in i beg your pardon the circulation of electron density between the two atoms is equal.

The 2 chlorine atoms share the pair of electrons in the solitary covalent bond equally, and also the electron thickness surrounding the \\(\\ceCl_2\\) molecule is symmetrical. Additionally note the molecules in which the electronegativity difference is very small (

Polar Covalent Bonds

A link in which the electronegativity difference in between the atoms is in between 0.5 and 2.0 is called a polar covalent bond. A polar covalent bond is a covalent shortcut in i beg your pardon the atoms have actually an uneven attraction for electrons and so the share is unequal. In a polar covalent bond, periodically simply dubbed a polar bond, the distribution of electrons about the molecule is no longer symmetrical.

Figure \\(\\PageIndex3\\) In the polar covalent shortcut of \\(\\ceHF\\), the electron density is unevenly distributed. Over there is a higher density (red) close to the fluorine atom, and a lower density (blue) near the hydrogen atom.

An easy method to highlight the uneven electron distribution in a polar covalent bond is to usage the Greek letter delta \\(\\left( \\delta \\right)\\).

Figure \\(\\PageIndex4\\) usage of \\(\\delta\\) to show partial charge.

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The atom through the higher electronegativity acquires a partial negative charge, if the atom through the lesser electronegativity acquires a partial confident charge. The delta prize is supplied to suggest that the quantity of charge is much less than one. A crossed arrow can also be provided to suggest the direction of better electron density.


Electronegativity distinctions in bonding making use of Pauling scale. Using distinctions in electronegativity come classify bonds together covalent, polar covalent, or ionic.