Question

Define electronegativity

Answer 1

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used. Fluorine (the most electronegative element) is assigned a value of 4.0, and values range down to caesium and francium which are the least electronegative at 0.7.

Answer 2

$\sf{\underline{Electronegativity:}}$

$\bullet$ Electronegativity of an element is the tendency of an atom to attract the shared pair of electrons towards itself.

$\bullet$ Although a number of numerical scale of electronegativity such as Pauling scale, Mulliken-Jaffe scale, Allred Rochow scale have been developed.

$\bullet$Yet the Pauling scale is most widely used.

$\bullet$An American scientist Linus Pauling in 1922 assigned arbitrarily a value of 4.0 to fluoride, the element considered to have the greatest tendency to attract the shared pair of electrons.

$\bullet$Approximate values for the electronegativity of a few elements (on Pauling scale) are given below in the table.


(a) $\sf{\underline{Electronegativity\:values\:across\:the\:periods:}}$


$\begin{tabular}{|c|c|c|c|c|c|c|c|} \cline{1-8}Atom \: (Period\:II) &Li&Be&B&C&N&O&F \\ \cline{1-8}Electronegativity&1.0&1.5&2.0&2.5&3.0&3.5&4.0\\ \cline{1-8}Atom \: (Period\:III) &Na&Mg&Al&Si&P&S&Cl \\ \cline{1-8}Electronegativity&0.9&1.2&1.5&1.8&2.1&2.5&3.0\\ \cline{1-8} \end{tabular}$

(b) $\sf{\underline{Electronegativity\:values\:down\:a\:family:}}$

$\begin{tabular}{|c|c|c|c|c|c|} \cline{1-6}Atomic \: (Group\:1)&Li&Na&K&Rb&Cs \\ \cline{1-6}Electronegativity\:value&1.0&0.9&0.8&0.8&0.7\\ \cline{1-6}Atom \: (Group\:17)&F&Cl&Br&I&At \\ \cline{1-6}Electronegativity\:value&4.0&3.0&2.8&2.5&2.2\\ \cline{1-6} \end{tabular}$

$\sf{\underline{Note:}}$

The electronegativity of any given element is not constant, it varies depending on the element to which it is bonded.