--- title: "Electronegativity and the Polar Bond" description: "Unequal attraction for shared electrons gives a bond partial positive and negative charges. The strengths and directions of the bond dipoles determine whether their combined effect leaves the molecule" canonical: https://lightmysky.com/learn/science/electronegativity-and-the-polar-bond-mt_TwSlh2VvUT source: https://lightmysky.com/learn/science/electronegativity-and-the-polar-bond-mt_TwSlh2VvUT.md retrieved: 2026-11-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Electronegativity and the Polar Bond Unequal attraction for shared electrons gives a bond partial positive and negative charges. The strengths and directions of the bond dipoles determine whether their combined effect leaves the molecule polar. Subject: Science · Area: Matter & Materials · Ages 15 to 16 Page: https://lightmysky.com/learn/science/electronegativity-and-the-polar-bond-mt_TwSlh2VvUT ## Ready when they can - Use a periodic trend to say which of two atoms pulls the shared pair harder - Mark partial charges on a bond and explain what the symbols mean - Decide whether a molecule is polar overall, given both its bond polarities and its shape ## Lesson: When sharing electrons is unfair Electronegativity measures how strongly an atom attracts shared electrons. In H2, equal attraction gives an even electron distribution and a nonpolar bond. In H-Cl, the distribution shifts toward chlorine. Chlorine has a partial negative charge (delta minus); hydrogen has a partial positive charge (delta plus). These are not full ion charges. Electronegativity generally increases up a group and to the right across a period. Fluorine has the highest value. An electronegativity difference is a rough guide to bond type, not a fixed cutoff. H-Cl differs by 0.9 and H-F by 1.9; both share electrons unequally in polar covalent bonds. Sodium chloride, with a difference of 2.1, is ionic: attraction holds Na+ and Cl- ions together. Electron transfer can form these ions. A zero or tiny difference suggests nonpolar covalent bonding. Consider the elements too: two nonmetals usually share; a metal and a nonmetal often form ions. *(drawing: Rounded Pauling values. A higher bar means stronger attraction for shared electrons.)* **Example.** Each C-O bond in carbon dioxide is polar toward oxygen. CO2 is linear, so its two equal bond dipoles point in opposite directions and cancel. Water is bent, so its O-H dipoles combine to give an overall dipole. A molecule is polar when the combined dipole is nonzero. Two opposite dipoles cancel only if they are equal. Being straight or having some symmetry is not enough on its own. **Tip.** When you meet a new molecule, work in three steps. First sketch its shape: straight, bent, or something else. Then draw each bond pull as an arrow toward the stronger puller. Last, add the arrows: opposite equal arrows cancel, angled arrows combine. Try it on an N-H bond: the trend says nitrogen pulls harder than hydrogen, so nitrogen gets delta minus. **Recap.** Unequal sharing makes polar bonds. Molecular polarity depends on both bond-dipole strengths and the directions set by the molecule's shape. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Molecular Shapes from Electron Pair Repulsion](https://lightmysky.com/learn/science/molecular-shapes-from-electron-pair-repulsion-mt_Of6ZxYjOsn) ## Optional connections - [Group 1, Group 7 and Group 0: Trends You Can Predict](https://lightmysky.com/learn/science/group-1-group-7-and-group-0-trends-you-can-predict-mt_cy1OrVAjIo) ## Opens up - [Forces Between Molecules](https://lightmysky.com/learn/science/forces-between-molecules-mt_0uBZWotvZB)