Electronegativity: Explanation, Factors Affecting, and Table

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Electronegativity is a measure of the attraction of an atom to bonding electrons in molecules relative to other atoms. The electronegativity values developed by Linus Pauling, an American chemist, are dimensionless numbers ranging from slightly less than one for alkali metals to a maximum of 4 for fluorine.

Large electronegativity numbers show a greater attraction to electrons than low electronegativity values.
On a periodic table, electronegativities increase from left to right.
Elements to the left of the periodic table have low electronegativities and are commonly referred to as electropositive elements.
The order of electronegativities F > O > N > C is an essential characteristic that will be used to describe the chemical properties of organic compounds.
Electronegativities decrease from top to bottom within a group of components.

Table of Content

What is Electronegativity?
Electronegativity Table
Factors Affecting Electronegativity
Periodic Trends in the Electronegativities of Elements
Most and Least Electronegative Elements
The Effect of Electronegativity on Covalent Bonding
Things to Remember
Sample Questions

Key Terms: Electronegativity, Atom, Molecule, Covalent bond, Periodic table of elements, Electrons, Atomic number, Nuclear charge, Fluorine, Cesium, Electronegativity chart, Electronegativity table

What is Electronegativity?

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“Electronegativity is the tendency of an atom in a molecule to attract the shared pair of electrons to itself.”

It is a dimensionless characteristic since it is only a tendency.

It basically represents the net result of the tendency of atoms in various elements to attract bond-forming electron pairs.
We measure electronegativity at various scales.
Linus Pauling designed the most commonly used scale.
According to this scale, fluorine has the highest electronegative value of 4.0, while cesium has the lowest electronegative value of 0.7.

Electronegativity Chart

Read more:

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Classification of Elements and Periodicity in Properties	Atomic Radius	Electron Gain Enthalpy
The d-Block Elements (Transition Elements)	Electronegativity Chart	Ionic Radius

Electronegativity Table

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The electronegativity of various elements is shown in the table below

Atomic Number	Element	Symbol	Electronegativity
1	Hydrogen	H	2.2
2	Helium	He	no data
3	Lithium	Li	0.98
4	Beryllium	Be	1.57
5	Boron	B	2.04
6	Carbon	C	2.55
7	Nitrogen	N	3.04
8	Oxygen	O	3.44
9	Fluorine	F	3.98
10	Neon	Ne	no data
11	Sodium	Na	0.93
12	Magnesium	Mg	1.31
13	Aluminium	Al	1.61
14	Silicon	Si	1.9
15	Phosphorus	P	2.19
16	Sulphur	S	2.58
17	Chlorine	Cl	3.16
18	Argon	Ar	no data
19	Potassium	K	0.82
20	Calcium	Ca	1
21	Scandium	Sc	1.36
22	Titanium	Ti	1.54
23	Vanadium	V	1.63
24	Chromium	Cr	1.66
25	Manganese	Mn	1.55
26	Iron	Fe	1.83
27	Cobalt	Co	1.88
28	Nickel	Ni	1.91
29	Copper	Cu	1.9
30	Zinc	Zn	1.65
31	Gallium	Ga	1.81
32	Germanium	Ge	2.01
33	Arsenic	As	2.18
34	Selenium	Se	2.55
35	Bromine	Br	2.96
36	Krypton	Kr	3
37	Rubidium	Rb	0.82
38	Strontium	Sr	0.95
39	Yttrium	Y	1.22
40	Zirconium	Zr	1.33
41	Niobium	Nb	1.6
42	Molybdenum	Mo	2.16
43	Technetium	Tc	1.9
44	Ruthenium	Ru	2.2
45	Rhodium	Rh	2.28
46	Palladium	Pd	2.2
47	Silver	Ag	1.93
48	Cadmium	Cd	1.69
49	Indium	In	1.78
50	Tin	Sn	1.96
51	Antimony	Sb	2.05
52	Tellurium	Te	2.1
53	Iodine	I	2.66
54	Xenon	Xe	2.6
55	Cesium	Cs	0.79
56	Barium	Ba	0.89
57	Lanthanum	La	1.1
58	Cerium	Ce	1.12
59	Praseodymium	Pr	1.13
60	Neodymium	Nd	1.14
61	Promethium	Pm	1.13
62	Samarium	Sm	1.17
63	Europium	Eu	1.2
64	Gadolinium	Gd	1.2
65	Terbium	Tb	1.22
66	Dysprosium	Dy	1.23
67	Holmium	Ho	1.24
68	Erbium	Er	1.24
69	Thulium	Tm	1.25
70	Ytterbium	Yb	1.1
71	Lutetium	Lu	1.27
72	Hafnium	Hf	1.3
73	Tantalum	Ta	1.5
74	Tungsten	W	2.36
75	Rhenium	Re	1.9
76	Osmium	Os	2.2
77	Iridium	Ir	2.2
78	Platinum	Pt	2.28
79	Gold	Au	2.54
80	Mercury	Hg	2
81	Thallium	Tl	1.62
82	Lead	Pb	2.33
83	Bismuth	Bi	2.02
84	Polonium	Po	2
85	Astatine	At	2.2
86	Radon	Rn	no data
87	Francium	Fr	0.7
88	Radium	Ra	0.89
89	Actinium	Ac	1.1
90	Thorium	Th	1.3
91	Protactinium	Pa	1.5
92	Uranium	U	1.38
93	Neptunium	Np	1.36
94	Plutonium	Pu	1.28
95	Americium	Am	1.3
96	Curium	Cm	1.3
97	Berkelium	Bk	1.3
98	Californium	Cf	1.3
99	Einsteinium	Es	1.3
100	Fermium	Fm	1.3
101	Mendelevium	Md	1.3
102	Nobelium	No	1.3
103	Lawrencium	Lr	no data
104	Rutherfordium	Rf	no data
105	Dubnium	Db	no data
106	Seaborgium	Sg	no data
107	Bohrium	Bh	no data
108	Hassium	Hs	no data
109	Meitnerium	Mt	no data
110	Darmstadtium	Ds	no data
111	Roentgenium	Rg	no data
112	Copernicium	Cn	no data
113	Nihonium	Nh	no data
114	Flerovium	Fl	no data
115	Moscovium	Mc	no data
116	Livermorium	Lv	no data
117	Tennessine	Ts	no data
118	Oganesson	Og	no data

Factors Affecting Electronegativity

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The following are the factors that affect Electronegativity

Size of an Atom

As an atomic size increases, the value of electronegativity decreases. This is due to the fact that electrons further away from the nucleus experience less force of attraction.

Nuclear Charge

A higher nuclear charge corresponds to a higher electronegativity value. This occurs because an increase in nuclear charge creates stronger electron attraction.

Substituent Effect

The electronegativity of an atom is determined by the type of substituent attached to it. For example, the carbon atom in CF₃I has a higher positive charge than the carbon atom in CH₃I.

As a result, the C atom in CF₃I is more electronegative than in CH₃I.
Substituents cause an atom's electronegativity to change, resulting in a change in the atom's chemical behavior.

Periodic Trends in the Electronegativities of Elements

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As we traverse from left to right across a period, the nuclear charge increases and the atomic size decreases, hence the value of electronegativity increases across the modern periodic table.

For example, the electronegativity trend in period 3 of the periodic table is shown below.

Electronegativity Trend: Across the Period

Electronegativity Trend: Across the Period

The atomic number increases as we move down the group in the modern periodic table.

The nuclear charge also increases, but the effect is overcome by the addition of one shell.
As a result, the value of electronegativity decreases as we move down the group.

For example, in the halogen group, as we go down the group from fluorine to astatine, the electronegativity value decreases, as shown in the image below.

Electronegativity Trend: Down the Group

Electronegativity Trend: Down the Group

It is a common observation that metals have lower electronegativity than nonmetals.

As a result, metals are electropositive, whereas nonmetals are electronegative.
Period two elements have different characteristics than their group elements because of their small size and increased electronegativity.
The elements in the second period resemble those in the next group in period three.
This is due to a little difference in their electronegativities. This results in the creation of a diagonal relationship.

Most and Least Electronegative Elements

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The most electronegative element in the periodic table is Fluorine having a value of electronegativity is 3.98.

Cesium is the least electronegative element. The electronegativity value is 0.79.

Since electropositivity is the inverse of electronegativity, we can say that Cesium is the most electropositive element.

The elements that require only a few electrons to complete their valence shells and have the fewest inner electron shells between the positive nucleus and the valence electrons are the most electronegative.

Fluorine is the element with the highest electronegative.
The electronegativity is 4.0. Metals have electronegativities below 2.0.
Cesium (Cs) and francium (Fr) have the lowest electronegative values, both at 0.7.

The Effect of Electronegativity on Covalent Bonding

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The electronegativities of the two bound atoms play a big role in the strength of a covalent bond (especially the difference in the electronegativities of the bonded atoms).

Since, the electronegativities of the bound atoms are the same, homonuclear diatomic molecules have comparatively "pure" covalent bonds (resulting in the bonded pair of electrons being almost equidistant from the two bonded nuclei).
H₂ molecules, Cl₂ molecules, and O₂ molecules are all examples of covalent bonding.
Covalent bonds between two species with different electronegativities, on the other hand, tend to become polarised.
This happens because the more electronegative atom pulls the electrons in the bond pair closer to itself, resulting in a partial negative charge.
The more electropositive atom develops a partial positive charge (denoted by +) at the same moment.
The polarity of the chemical bond is determined by these partial charges.

Things to Remember

Electronegativity is the tendency of an atom in a molecule to attract the shared pair of electrons towards itself.
As we move across a period from left to right, the nuclear charge increases, and the atomic size decreases.
Electronegativity increases across a period in the modern periodic table.
As we move down the group in the modern periodic table, there is an increase in the atomic number.
The nuclear charge also increases but the effect of the increase in nuclear charge is overcome by the addition of one shell.
The value of electronegativity decreases as we move down the group.

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Electron Gain Enthalpy	Electronegativity	Packing Efficiency
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Sample Questions

Ques. What would be the IUPAC name and symbol for the element with atomic number 120? (1 Mark)

Ans. From the modern periodic table, the roots for 1, 2, and 0 are un, bi, and nil, respectively. Hence, the symbol and the name respectively are Ubn and unbinilium.

Ques. How would you justify the presence of 18 elements in the 5th period of the Periodic Table? (2 Marks)

Ans. When n = 5, l = 0, 1, 2, 3. The order in which the energy of the available orbitals

4d, 5s and 5p increases are 5s < 4d < 5p.

The total number of orbitals available is 9. The maximum number of electrons that can be accommodated is 18, and therefore 18 elements are there in the 5th period.

Ques. Show by a chemical reaction with water that Na₂O is a basic oxide and Cl₂O₇ is an acidic oxide. (2 Marks)

Ans. Na2O with water forms a strong base whereas Cl₂O₇ forms a strong acid.

Na₂O + H₂O → 2NaOH

Cl₂O₇ + H₂O → 2HClO₄

Their basic or acidic nature can be qualitatively tested with litmus paper

Ques. Using the Periodic Table, predict the formulas of compounds that might be formed by the following pairs of elements:
(a) silicon and bromine (b) aluminum and sulfur. (3 Marks)

Ans. (a) Silicon is a group 14 element with a valence of 4; bromine belongs to the halogen family with a valence of 1.

Hence the formula of the compound formed would be SiBr₄.

(b) Aluminium belongs to group 13 with a valence of 3; sulfur belongs to group 16 elements with a valence of 2.

Hence, the formula of the compound formed would be Al₂S₃

Ques. The elements Z = 117 and 120 have not yet been discovered. In which family/group would you place these elements and also give the electronic configuration in each case? (3 Marks)

Ans: The element with Z = 117, would belong to the halogen family(Group 17) and the electronic configuration would be [Rn]5f₁₄6d₁₀7s₂7p₅.

The element with Z = 120 will be placed in Group 2(alkaline earth metals) and will have the electronic configuration [Uuo]8s₂.

From left to right. Hence the order of increasing metallic character is: P < Si < Be < Mg < Na.

Ques. What is the ideal definition of electronegativity? (2 Marks)

Ans. The ability of an atom to attract an electron's binding pair is measured by electronegativity. A Pauling scale is most commonly used for it. Fluorine has a value of 4.0, whereas the least electronegative elements, cesium, and francium, have a value of 0.7.

Ques. What is the difference in electronegativity? (2 Marks)

Ans. Electronegativity explains the extent to which an atom attracts electrons in a chemical interaction. The type of the bond will be ionic if the difference in electronegativity is larger than 1.7. The type of the bond is polar covalent if the difference in electronegativity is between 0.4 and 1.7.

Ques. Is electronegativity a relative concept? (1 Mark)

Ans. The ability of an atom to attract electrons is known as electronegativity. It's proportional to the difference between an atom's ionization potential and its electron attraction.

Ques. What is the formula for calculating electronegativity? (2 Marks)

Ans. To find the difference, subtract the lesser electronegativity from the bigger one. If we're looking at the molecule HF, for example, we'd deduct hydrogen's electronegativity (2.1) from fluorine (4.0). 1.9 = 4.0 - 2.1

Ques. Which group is the least electronegative? (2 Marks)

Ans. The alkali metals are definitely the least electronegative, having the least nuclear charge for a given period, as well as the least shielding by other electrons (just one electron is present in their valence shells). The least electronegative group is VIII, the inert gas.

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Electronegativity: Explanation, Factors Affecting, and Table

What is Electronegativity?

Electronegativity Table