Step-by-Step Explanation:
1. Definition and Origin of Electronegativity:
The term electronegativity was first derived by Linus Pauling in 1932 for quantifying the ability of an atom to draw the electrons of a chemical bond. However, this concept is based on periodic trends. Electronegativity increases from left to right in a period but decreases while going down the group.
2. The Pauling Electronegativity Scale:
Linus Pauling proposed a scale for assessing electronegativity of the elements: 0.7 as the least and francium, and his scale runs to 4.0 for the most electronegative, which in existence is the element fluorine. Many elements range between 0.7 and 4.0 on the scale of Pauling.
3. Along with Chemical Bonding:
Electronegativity is one such property that defines the nature of various types of bonds formed between the atoms in a compound. If two different atoms have dissimilar electronegativity values, then they can form ionic or covalent bond between them because it depends mainly upon the difference in their values of electronegativity.
A significant difference between the atoms leads to ionic bonding, in which the electrons are fully transferred from one atom to the other, while a minor difference leads to covalent bonding, in which the electrons are shared.
4. Periodic Trends
The periodic table indicates that electronegativity increases from left to right. This is so because there is an increase in nuclear charge as well as enhanced effective nuclear attraction. However, moving down a group, one may observe that electronegativity tends to decrease, based on the increasing atomic size that positions the outer electrons farther away from the nucleus.
Halogens are like elements on the right side of the periodic table; they tend to be more electronegative than elements on the left side that include the alkali metals.
5. Application to Bonding and Polarity:
The values of electronegativity are handy in pre-determining the kind of molecular polarity. In a covalent bond, shared electrons are drawn closer toward the atom which has more electronegativity. In this manner, a partial negative charge (δ-) is formed on that particular atom and the least electronegative atom shall be partially positively charged (δ+). Polar covalent bonds develop due to the unequal sharing of electrons between atoms. Nonpolar covalent bonds develop between atoms when they share equal electrons since their electronegativities are nearly equal.
6. Illustration of difference in electronegativity:
For example, in the HCl molecule of hydrogen chloride, chlorine is more electronegative than hydrogen. Therefore, when the shared electrons are pulled stronger by chlorine, then this is the polar covalent where the chlorine atom has partial negativity while the hydrogen has partial positivism. Conversely, the nitrogen molecule N2 has two atoms that equal electronegativity, hence forms a nonpolar covalent bond.
7. Electronegativity and Chemical Reactivity In this way, electronegativity also determines the reactivity of elements and compounds. The elements with higher electronegativity generally form stronger bonds with elements and exhibit lower reactivity with other substances as compared to those with low electronegativity, which is generally more reactive because their capacity to attract electrons has diminished. 8. Measure and compute There are different scales that help in the quantitative measurement of the values of electronegativity. There the Pauling scale, Mulliken scale, and Allred-Rochow scale which determines the electronegativity. Though the values may vary a little from one element to another, all the scales measure the electron-attracting ability of each atom.
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