Question 1

What is electronegativity?

Accepted Answer

Electronegativity measures how strongly an atom pulls shared electrons toward itself in a chemical bond. It's not a physical force you can measure directly like mass or charge -- it's a relative, dimensionless number derived from comparing bond energies, which is why it's given on a scale (Pauling's) rather than in physical units.

Question 2

Why is fluorine the most electronegative element?

Accepted Answer

Fluorine has a small atomic radius and a nearly-full outer shell (7 of 8 electrons), so its nucleus pulls hard on any shared electron pair while that electron has to travel only a short distance. Both effects push in the same direction, giving fluorine the highest Pauling value of any element, 3.98.

Question 3

Why don't the noble gases have an electronegativity value?

Accepted Answer

Pauling's scale is built from real bond energies between different elements, and helium, neon and argon essentially don't form chemical bonds, so there's no bond-energy data to calculate a value from. Krypton and xenon are exceptions -- both form a handful of real compounds (like XeF4), so they do have measured or estimated values (3.00 and 2.6).

Question 4

How do I use electronegativity to predict whether a bond is ionic, polar covalent, or nonpolar covalent?

Accepted Answer

Take the difference between the two atoms' electronegativity values. As a rule of thumb: a difference under about 0.5 is nonpolar covalent, 0.5 to about 1.7 is polar covalent, and above about 1.7 is considered ionic. These cutoffs are a teaching approximation, not a hard physical boundary -- real bonds fall on a continuous spectrum.

Question 5

Is electronegativity the same as electron affinity?

Accepted Answer

No, though they're often confused. Electron affinity is the actual energy released when a free, isolated atom gains one electron -- a directly measurable quantity in a defined unit (kJ/mol). Electronegativity is a broader, unitless tendency describing how an atom behaves inside a bond, and it's calculated from bond energies, not measured directly on a lone atom.

Question 6

Why is francium listed as less electronegative than cesium, when the trend down a group should make them nearly identical or reversed?

Accepted Answer

Historical accident, not new chemistry. Pauling originally assigned both cesium and francium 0.7 in 1932. Cesium's value was later refined to 0.79 using better bond-energy data, but francium is so rare and radioactive that no comparable experiment has ever been done on it, so its original 0.7 estimate was simply never updated. Some theoretical work actually suggests francium is slightly more electronegative than cesium.

Question 7

Is Pauling's the only electronegativity scale?

Accepted Answer

No -- Mulliken, Allred-Rochow, and Allen scales all exist and rank elements similarly but calculate the number differently (from ionization energy and electron affinity, from effective nuclear charge, or from spectroscopic term values). Pauling's is used here because it's the original, most widely taught, and most commonly printed on classroom periodic tables.

#	Symbol	Element	Electronegativity
Period 1
1	H	Hydrogen	2.20
2	He	Helium	—
Period 2
3	Li	Lithium	0.98
4	Be	Beryllium	1.57
5	B	Boron	2.04
6	C	Carbon	2.55
7	N	Nitrogen	3.04
8	O	Oxygen	3.44
9	F	Fluorine	3.98
10	Ne	Neon	—
Period 3
11	Na	Sodium	0.93
12	Mg	Magnesium	1.31
13	Al	Aluminum	1.61
14	Si	Silicon	1.90
15	P	Phosphorus	2.19
16	S	Sulfur	2.58
17	Cl	Chlorine	3.16
18	Ar	Argon	—
Period 4
19	K	Potassium	0.82
20	Ca	Calcium	1.00
21	Sc	Scandium	1.36
22	Ti	Titanium	1.54
23	V	Vanadium	1.63
24	Cr	Chromium	1.66
25	Mn	Manganese	1.55
26	Fe	Iron	1.83
27	Co	Cobalt	1.88
28	Ni	Nickel	1.91
29	Cu	Copper	1.90
30	Zn	Zinc	1.65
31	Ga	Gallium	1.81
32	Ge	Germanium	2.01
33	As	Arsenic	2.18
34	Se	Selenium	2.55
35	Br	Bromine	2.96
36	Kr	Krypton	3.00
Period 5
37	Rb	Rubidium	0.82
38	Sr	Strontium	0.95
39	Y	Yttrium	1.22
40	Zr	Zirconium	1.33
41	Nb	Niobium	1.60
42	Mo	Molybdenum	2.16
43	Tc	Technetium	1.90
44	Ru	Ruthenium	2.20
45	Rh	Rhodium	2.28
46	Pd	Palladium	2.20
47	Ag	Silver	1.93
48	Cd	Cadmium	1.69
49	In	Indium	1.78
50	Sn	Tin	1.96
51	Sb	Antimony	2.05
52	Te	Tellurium	2.10
53	I	Iodine	2.66
54	Xe	Xenon	2.60
Period 6
55	Cs	Cesium	0.79
56	Ba	Barium	0.89
57	La	Lanthanum	1.10
58	Ce	Cerium	1.12
59	Pr	Praseodymium	1.13
60	Nd	Neodymium	1.14
61	Pm	Promethium	1.13*
62	Sm	Samarium	1.17
63	Eu	Europium	1.20*
64	Gd	Gadolinium	1.20
65	Tb	Terbium	1.10
66	Dy	Dysprosium	1.22
67	Ho	Holmium	1.23
68	Er	Erbium	1.24
69	Tm	Thulium	1.25
70	Yb	Ytterbium	1.10*
71	Lu	Lutetium	1.27
72	Hf	Hafnium	1.30
73	Ta	Tantalum	1.50
74	W	Tungsten	2.36
75	Re	Rhenium	1.90
76	Os	Osmium	2.20
77	Ir	Iridium	2.20
78	Pt	Platinum	2.28
79	Au	Gold	2.54
80	Hg	Mercury	2.00
81	Tl	Thallium	1.62
82	Pb	Lead	2.33
83	Bi	Bismuth	2.02
84	Po	Polonium	2.00
85	At	Astatine	2.20*
86	Rn	Radon	—
Period 7
87	Fr	Francium	0.70*
88	Ra	Radium	0.90
89	Ac	Actinium	1.10
90	Th	Thorium	1.30
91	Pa	Protactinium	1.50
92	U	Uranium	1.38
93	Np	Neptunium	1.36
94	Pu	Plutonium	1.28
95	Am	Americium	1.30
96	Cm	Curium	1.30
97	Bk	Berkelium	1.30
98	Cf	Californium	1.30
99	Es	Einsteinium	1.30
100	Fm	Fermium	1.30
101	Md	Mendelevium	1.30
102	No	Nobelium	1.30
103	Lr	Lawrencium	—
104	Rf	Rutherfordium	—
105	Db	Dubnium	—
106	Sg	Seaborgium	—
107	Bh	Bohrium	—
108	Hs	Hassium	—
109	Mt	Meitnerium	—
110	Ds	Darmstadtium	—
111	Rg	Roentgenium	—
112	Cn	Copernicium	—
113	Nh	Nihonium	—
114	Fl	Flerovium	—
115	Mc	Moscovium	—
116	Lv	Livermorium	—
117	Ts	Tennessine	—
118	Og	Oganesson	—

Electronegativity Chart (Pauling Scale)

What Electronegativity Measures

Worked example: is H–F polar or nonpolar?

Common mistake

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Frequently Asked Questions