Sähkönegatiivinen

Sähkönegatiivinen refers to the tendency of an atom to attract a shared pair of electrons (or electron density) towards itself in a chemical bond. This property is a fundamental concept in chemistry, particularly when understanding the nature of covalent bonds. When two atoms with different electronegativities form a covalent bond, the electrons are not shared equally. The atom with higher electronegativity will pull the electron density closer to its nucleus, resulting in a polar covalent bond. If the electronegativity difference is very large, the bond can become ionic, where the electron is essentially transferred from one atom to another, forming ions.

Several scales exist to quantify electronegativity, with the Pauling scale being the most widely used. On this scale, fluorine is the most electronegative element, assigned a value of approximately 4.0. Other highly electronegative elements include oxygen, nitrogen, and chlorine. Conversely, elements on the left side of the periodic table, such as alkali metals and alkaline earth metals, are electropositive, meaning they tend to lose electrons rather than attract them. Electronegativity generally increases across a period from left to right and decreases down a group in the periodic table. This trend is influenced by factors such as nuclear charge and atomic radius. Understanding electronegativity is crucial for predicting molecular polarity, reactivity, and the types of bonds that will form between elements.