elektronegativitással

Elektronegativitás (electronegativity) is a chemical property that describes the tendency of an atom to attract a shared pair of electrons (or electron density) in a chemical bond. It is a relative scale, meaning that the electronegativity of an atom is compared to that of other atoms. The concept was first introduced by Linus Pauling in 1932.

Electronegativity is not a directly measurable quantity but is derived from various experimental data such as bond energies. The most commonly used scale is the Pauling scale, where fluorine is assigned the highest value of 4.0. Other elements have values relative to this. Generally, electronegativity increases across a period in the periodic table from left to right and decreases down a group from top to bottom. This trend is influenced by factors such as nuclear charge and atomic radius.

The difference in electronegativity between two bonded atoms is crucial in determining the type of chemical bond that forms. If the electronegativity difference is very small or zero, the bond is considered nonpolar covalent, meaning electrons are shared equally. If the difference is moderate, the bond is polar covalent, where electrons are shared unequally, creating partial positive and partial negative charges on the atoms. If the electronegativity difference is large, the bond is considered ionic, where one atom essentially "takes" the electron from the other, forming ions.

Electronegativity plays a significant role in understanding molecular polarity, reaction mechanisms, and predicting the physical and chemical properties of substances.