Electronegativity

High School

Definition

A measure of how strongly an atom attracts the shared pair of electrons in a chemical bond. Electronegativity increases across a period and decreases down a group, and differences in electronegativity between atoms determine whether a bond is ionic, polar, or non-polar.

Worked examples

Fluorine (\(3.98\)) has the highest electronegativity, while francium (\(0.7\)) has the lowest.

Electronegativity values range from near zero to four on the Pauling scale.

In \(\)HCl\(\), chlorine (\(3.16\)) attracts electrons more strongly than hydrogen (\(2.20\)), making the bond polar.

The difference of \(0.96\) creates a partial negative charge on chlorine and partial positive on hydrogen.

\(\)NaCl\(\): difference \(3.16 - 0.93 = 2.23\) (ionic); \(\)Cl\(_2\): difference \(0\) (non-polar covalent).

Large differences (usually \(>1.7\)) indicate ionic bonds; zero difference means electrons are shared equally.

Common mistakes

Electronegativity increases down a group because atoms get larger → Electronegativity decreases down a group as electrons are farther from the nucleus Larger atoms hold bonding electrons more weakly, so they attract shared electrons less strongly.
A polar bond means the molecule is polar → A molecule with polar bonds can be non-polar if the bond dipoles cancel Molecular shape matters: \(\)CO\(_2\) has polar bonds but is linear, so dipoles cancel and it is non-polar.
Electronegativity is the same as electron affinity → Electronegativity measures attraction in a bond; electron affinity is energy change when gaining an electron Electronegativity is a relative property for bonded atoms, while electron affinity applies to isolated atoms.

Where you'll use it next

You'll use electronegativity to predict bond types and molecular polarity in chemistry, understand reaction mechanisms in organic chemistry, and explain solubility and intermolecular forces in physical chemistry and biochemistry.

Found in 1 StudyPug lesson

Mastering Electronegativity: Periodic Trends in Chemistry

Chemistry 11

Dive into the world of electronegativity and its periodic trends. Understand how it varies across the periodic table, influencing chemical bonding and reactivity. Boost your chemistry skills today!

11th Grade11th