Electronegativity: the tug-of-war for electrons

4 minAS Level3.1.13.1.2

AI-drafted, independently checked · not yet teacher-reviewed

By the end of this lesson

By the end you can define electronegativity and explain how nuclear charge, atomic radius and shielding decide how strongly an atom attracts electrons.

Sharing isn't always fair

In a covalent bond, two atoms share a pair of electrons. Picture a tug-of-war, with the electron pair as the rope.

If both atoms pull equally, as in $\text{Cl}_2$ , the pair sits right in the middle. If one pulls harder, as in $\text{HCl}$ , the pair shifts towards the stronger puller: chlorine wins.

Definition

Electronegativity

The power of an atom to attract electrons to itself.

In practice, "electrons" means the bonding pair: the shared electrons in a covalent bond.

The Pauling scale

Electronegativity is a number on the Pauling scale. It has no units.
Fluorine is the most electronegative element, at 4.0.
Caesium is down near the bottom, at about 0.8.
In exams, Pauling values are given when you need them. No need to memorise a table.

Quick check

DefinitionQuestion 1 · Recall

Define electronegativity.

Fill in the blanksQuestion 2 · Recall

Electronegativity values are given on the scale. They have units, and the most electronegative element, , has a value of 4.0.

Answer the 2 questions above to continue.

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