Nonpolar covalent bonding explains why many molecules have bonds with shared electrons but little to no charge separation. This page focuses on how similar electronegativity values lead to essentially equal sharing in a covalent bond.

Core idea: similar electronegativity means equal sharing

Electronegativity and electron sharing

When two bonded atoms have similar electronegativities, neither atom can “pull” the bonding electrons much more strongly than the other. As a result, the bonding electron density is approximately symmetric between the nuclei, and the bond is considered nonpolar covalent.

To discuss “similar” quantitatively, chemists often compare electronegativity values on the same scale (typically Pauling).

Periodic trends in Pauling electronegativity across the first six periods. The plot highlights the systematic rise toward the upper-right region of the periodic table, which explains why atoms in similar regions often have comparable electronegativity values (and therefore more equal electron sharing). Source

The key comparison is the electronegativity difference.

A small $\Delta EN$ supports the prediction of nonpolar covalent bonding, but AP Chemistry emphasises the conceptual link: similar attraction strengths produce shared electrons without meaningful partial charges.

Graphical representation of Pauling’s relationship between electronegativity difference and estimated ionic character of a bond. The curve makes the modeling point explicit: as $\Delta EN$ increases, the bond gains a larger ionic contribution (greater charge separation), whereas small $\Delta EN$ stays largely covalent. Source

What “nonpolar covalent” means in bonding terms

In a nonpolar covalent bond:

• The bonding pair is located roughly midway between the atoms (on average).

• Any partial charges ($\delta^+$ and $\delta^-$) are absent or extremely small.

• The bond is best modelled as equal electron sharing, not electron transfer.

Recognising nonpolar covalent bonds on the AP level

Common cases where electronegativities are identical or very close

Bonds are strongly predicted to be nonpolar covalent when:

• The atoms are the same element (homonuclear diatomics), so electronegativity values are identical (e.g., $H_2$, $N_2$, $Cl_2$).

• The atoms are different but have very similar electronegativities, so the shared electrons are not significantly displaced toward either atom.

Because electronegativity values are comparative and depend on scale and context, AP Chemistry typically expects you to use:

Reference diagram summarizing Pauling-scale electronegativity values alongside common interpretive ranges used in introductory chemistry. It helps students translate “similar electronegativities” into a practical decision-making framework for classifying bonds as nonpolar covalent versus increasingly polar/ionic as $\Delta EN$ grows. Source

• The relative electronegativity relationship (similar vs. different), and

• The bond description (equal sharing vs. unequal sharing), rather than strict numerical cutoffs.

The important exception-style idea: C–H bonds are effectively nonpolar

The syllabus highlights that many C–H bonds are effectively nonpolar despite a small electronegativity difference. This reflects how AP Chemistry treats bond polarity as a model with practical thresholds.

Key points for C–H:

• Carbon is slightly more electronegative than hydrogen, so $\Delta EN$ is not zero.

• Nevertheless, the electron sharing in a C–H bond is close enough to equal that the bond is commonly treated as nonpolar for predicting many molecular properties.

• This “effective” nonpolarity is especially useful in recognising that many hydrocarbons consist largely of nonpolar bonds, so their electron distribution is not strongly separated by individual C–H bonds.

Using the model correctly (and avoiding common mistakes)

What you should and should not claim from “similar electronegativity”

From similar electronegativity, you should conclude:

• The bond is covalent (electrons are shared).

• The bond is nonpolar covalent (sharing is approximately equal).

• The bond will not create a strong separation of charge within that bond.

You should avoid overextending the idea by:

• Treating $\Delta EN$ as a single rigid rule that guarantees all properties.

• Assuming a tiny $\Delta EN$ always implies perfectly identical electron density; “nonpolar” is a simplified but useful model.

Language that matches AP scoring expectations

High-utility phrasing for explanations:

• “Because the atoms have similar electronegativities, they share the bonding electrons approximately equally, so the bond is nonpolar covalent.”

• “Although C–H has a small electronegativity difference, it is often treated as effectively nonpolar, so it does not contribute strongly to charge separation.”