At the end of the article, you will know – How to Calculate Electronegativity – Periodic Table, Examples, Table, Chart. Let’s start discussing each and every point.
When two different atoms in a molecule are bonded together by a covalent bond, the electron pair forming the bond is not shared equally by both the atoms. In other words, the shared pair of electrons do not lie in the middle of the molecules but shift towards the atom having greater electron affinity.
The tendency of an atom to attract electrons to itself when combined in a compound is called electronegativity (E.N).
For example – In the molecule of hydrogen chloride electron pair is attracted more towards chlorine. It is because the chlorine is more electronegative than hydrogen.
- The value of E.N depends upon the ionization potential and electron affinity of the atom.
- A smaller size of an atom attracts electrons more than the large ones.
- Low E.N is the characteristic of metals and high E.N is the characteristic of nonmetals.
Must Read – E.N Difference
Electronegativity Table Chart
The value of the E.N depends on the following factors.
- The size of the atom (Atomic Radius)
- Electronic configuration.
- Nuclear attraction.
- Oxidation state.
- Percentage s –character
How to Calculate Electronegativity – Find Electronegativity
Since E.N of elements is a relative property, it has no units. Electronegativity may be expressed on the following three scales. There were many scientists who explain E.N with different scale of comparison. Out of these Pauling, scales is the most commonly used.
In this Mulliken scale, E.N is taken as an average of ionization energy and electron affinity.
The relationship between the Pauling and Mulliken E.N scale as:
Allred and Rochow defined E.N as the electrostatic force exerted by the nucleus on the valence electrons. Thus,
where Z is the effective nuclear charge and r is the covalent radius of the atom in Å.
It is based on excess bond energies. He determined E.N difference between the two atoms and then by assigning arbitrary values to few elements (e.g. 4.00 to fluorine, 2.5 to carbon and 2.1 to hydrogen). He calculated the E.N of the other elements.
Electronegativity Periodic Table
E.N of elements is inversely proportional to the atom radius. Atomic radius will increase down to group and decreases along period. It means E.N behavior will be opposite to atomic radius.
- In a period, the E.N of elements increases from left to right. This is due to decrease in size and increase in nuclear charge. Thus the alkali metals possess the lowest value, while the halogens have the highest. Inert gases have zero E.N.
- In a group, the E.N of elements decreases from top to bottom. This is due to increase in atomic Size.
When a bond is formed between the atoms two or more different elements. The type of bond is (whether it is ionic or covalent or any type of bond) mostly depends upon the concept of E.N.
Electronegativity of Oxygen
- Pauling scale helps to measure the E.N value of oxygen.
- Oxygen has a value of 3.44
- Its value is higher than Bromine but lesser than Fluorine.
- Order of E.N of some elements is F>O>Cl=N>Br>C>I>H.
Electronegativity of Carbon
- There is zero difference in E.N when bond exists between carbon bonds.
- Its electronegative value is 2.55.
- It shows value less than Nitrogen(3.0) but more than Boron (2.0) and Silicon (1.8).
- This cause the tendency to form millions of compound with hydrogen.
Electronegativity of Hydrogen
- The value of E.N makes it unique element.
- Its value of E.N is 2.2.
- When Hydrogen placed with metal it behaves as a metal, when form bond with non-metal it shows the behavior like of metals.
This is about basics of – How to Calculate Electronegativity – Periodic Table, Examples, Table, Chart.