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Two scales of electronegativity are in common use: the Pauling scale (proposed in 1932) and the Mulliken scale (proposed in 1934). There is also a Allred-Rochow scale.

1 Pauling Scale

The Pauling scale was devised in 1932. On this scale, the most electronegative element ( fluorine) is given an electronegativity value of 4.0; the least electronegative element ( francium) has a value of 0.7, and the remaining elements have values in between. The elements in the second period of the periodic table are sometimes given rounded values (to make them easier to remember):

• Li: 1.0
• Be: 1.5
• B: 2.0
• C: 2.5
• NNitrogen is the chemical element in the periodic table that has the symbol N and atomic number 7. A common normally colorless, odorless, tasteless and mostly inert diatomic non-metal gas, nitrogen constitutes 78 percent of Earth's atmosphere and is a cons: 3.0
• OOxygen is the chemical element in the periodic table that has the symbol O and atomic number 8. The element is very common, found not only on Earth but throughout the universe. Molecular oxygen (O, often called free oxygen on Earth is thermodynamically un: 3.5
• F: 4.0

On the Pauling scale, hydrogenhydrogen helium H Li Full table General Name, Symbol, NumberHydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1 (IA), 1 , s Density, Hardness 0. 0899 kg/m3, NA Appearance colorless Atomic properties Atomic weight 1. 00794 amu Atomic radius (ca is arbitrarily assigned a value of 2.1 or 2.2.

2 Mulliken Scale

On the Mulliken scale, numbers are obtained by averaging ionization potential and electron affinityIn chemistry, electron affinity is the amount of energy absorbed when an electron is added to a neutral isolated gaseous atom to form a gaseous ion with a 1- charge. It has a negative value if energy is released. Most elements have a negative electron aff. Consequently, the Mulliken electronegativities are expressed directly in energyThis article is about the scientific concept. Energy use by humans is discussed in other articles''. Energy generally and qualitatively speaking, is the property (or the quantity of the property) of doing things or supplying power. The expressions energy units, usually electron volts.

3 Electronegativity Trends

Each element has a characteristic electronegativity ranging from 0 to 4 on the Pauling scale. A strongly electronegative element, like fluorine, has an electronegativity of 4 while weakly electronegative elements, such as lithium, have values close to 1. Electronegativity trends are to higher values for elements in the top right of the periodic table. Bonds between atoms with a large electronegativity difference (greater than or equal to 2.0 on the Pauling scale) are usually considered to be ionic, while values between 2.0 and 0.4 are considered polar covalent. Values below 0.4 are considered non-polar covalent bonds.

Electronegativity decreases down the periodic table and increases across, as shown below. Additionally, atomic radius decreases across but ionization energy increase.