Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Electronegativity is defined as a qualitative measure of the ability of an atom in a chemical compound to attract shared electrons towards itself.
Unlike electron gain enthalpy, electronegativity is not a measurable quantity; it is a relative value assigned to elements.
On the Pauling scale, Fluorine () is assigned the highest value of , while Cesium () has one of the lowest values at .
Across a period (left to right), electronegativity increases due to the increase in effective nuclear charge () and decrease in atomic radius.
Down a group, electronegativity decreases because the atomic radius increases and the shared pair of electrons is further from the nucleus.
Electronegativity is directly related to non-metallic character; hence, non-metals have high electronegativity while metals have low electronegativity.
The hybridization of an atom affects its electronegativity: an atom in hybridization is more electronegative than , which is more electronegative than due to the increase in -character.
📐Formulae
💡Examples
Problem 1:
Arrange the following elements in increasing order of electronegativity: , , , .
Solution:
Explanation:
These elements belong to the same period (Period 2). Electronegativity increases from left to right across a period as the atomic size decreases and the effective nuclear charge increases.
Problem 2:
Compare the electronegativity of in , , and .
Solution:
Explanation:
As the -character of the hybrid orbital increases ( in , in , in ), the electrons are held more tightly by the nucleus, resulting in higher electronegativity.
Problem 3:
Which element has the highest electronegativity in the periodic table and why?
Solution:
Fluorine ()
Explanation:
Fluorine has the smallest atomic radius and highest effective nuclear charge among the reactive elements (excluding noble gases), giving it the strongest tendency to attract a shared pair of electrons.