Coulombic attraction: definition in chemistry
Coulombic attraction: The electrostatic force that pulls oppositely charged particles toward each other, such as a positive nucleus and a negative electron.
According to Coulomb's law, the force grows with the size of the charges and weakens quickly as the distance between them increases. This one idea explains a great deal of chemistry: why outer electrons in large atoms are easy to remove, why ionic compounds hold together and why ions with larger charges form compounds with higher melting points. Particles with like charges feel the opposite effect, Coulombic repulsion.
Examples
- Na⁺ and Cl⁻ ions held together in a salt crystal
- MgO, with 2+ and 2− ions, melts near 2,800 °C; NaCl melts at 801 °C
- A nucleus holding its electrons in place
- Cesium's outer electron is far from the nucleus, so it is easily removed
On the periodic table
Coulombic attraction explains the main trends on the table: atoms shrink and hold electrons more tightly across a period as nuclear charge grows, and loosen their grip down a group as electrons sit farther out.