For exact values you must consult a table, such as one found in a chemistry book.
Flourine (upper right on the Periodic Table) has the highest electronegativity value of 4.0.
Francium (lower left on the periodic table) has the lowest value of 0.7.
As far as general trends go, the closer to fluorine you are the more electronegative the element, and the closer to francium you are the less electronegative the element.
Perhaps the most popular method of determining electronegativity is through Linus Pauling (1901-1995)'s model.
To elaborate on this, I'll use a hypothetical example with a molecule HX. The formula that Pauling used to calculate electronegativity (EN) differences is:
EN(X)-EN(H)=0.0102 (difference)^0.5.
Note: most of the elements in the Periodic Table have their electronegativities calculated already. Since Pauling's formula only calculates differences, it is crucial that we are given the electronegativity of the one of the atoms in a compound before being able to perform our calculations.
In his formula, EN(X) stands for the electronegativity of the X atom and EN(H) stands for the electronegativity of the H atom. 0.0102 is the conversion factor between kilojoules and electron volts (which were the units that Pauling used). "Difference" is typically denoted with the delta symbol and stands for the difference between the actual bond energies that we measured and the expected bond energies.
What does "expected bond energy" mean?
(Note here that double hyphens represent a bond not a minus sign)
The expected bond energy is the "average" of the H--H and X--X bond energies.
The expected H--X bond energy= [(H--H bond energy)(X--X bond energy)]^(1/2)
What does "measured bond energy" mean?
The "measured bond energy" is simply the experimental values of bond energies that one finds when conducting an experiment. There is no formula for this.
Now, difference=(H--X)expected - (H--X)measured.
Plug this back into Pauling's Formula.
Bond energies can simply be measured using thermodynamic experiments to see how much energy is lost (with a calorimeter or similar tool) upon dissociating a compound using chemical processes.
Electronegativity (EN) is the measure of an atom's ability to attract shared electrons in a covalent bond
Refer to the related link for a table of electronegativities of the elements.
an atom's attraction for shared electrons
Ability to gain electron .
The difference electronegativity values of sodium and bromine are; Sodium(Na) 0.9, Bromine(Br) 2.8 thus a difference of 1.9.
Answer The larger the difference in electronegativity the more ionic properties a bond is said to have. The smaller the difference in electronegativity the more covalent properties a bond is said to have The magic number is 1.7 , if electronegativity (EN) difference is less than 1.7 then it is covalent. if it is more, then its ionic bond.
Zero
The Pauling electronegativity of calcium is 1,00.The Pauling electronegativity of fluorine is 3,98.
This is a characteristic of a polar covalent bond.
Calcium Pauling electronegativity is 1.Fluorine Pauling electronegativity is 4.The difference is 3.
After Pauling rules the electronegativity of aluminium is 1,61 and the electronegativity of chlorine 3,16; the difference is 1,55.
Sodium electronegativity (after Pauling): 0,93 Bromine electronegativity (after Pauling): 2,96 The difference is 2,03.
If it is 1.35 it is polar covalent and it is a liquid. Why is it a solid?
Electronegativity of hydrogen is 2,20. Electronegativity of sodium is 0,93.
Sodium electronegativity (after Pauling): 0,93 Bromine electronegativity (after Pauling): 2,96 The difference is 2,03.
If there is a slight electronegativity difference, the bond is a nonpolar covalent bond. If there is a large electronegativity difference, it is an ionic bond. If the difference is somewhere between, it is a polar covalent bond.
The Pauling electronegativity of francium (metal) is 0,7 and the electronegativity of fluorine (nonmetal) is 3,98.
If the electronegativity difference is less than 2, then covalent bonds are formed. If the electronegativity difference is greater than 2, then ionic bonds are formed.
Nonpolar bonds show a Low electronegativity difference between atoms
SeCl4 would be non-polar covalent, because the electronegativity between Se and each Cl would be about the same. They differ by about 0.6. Don't multiply the the electronegativity by 4, because you want to find the difference between each Se---Cl bond. A polar molecule would have an electronegativity difference of less than 2. Electronegativity values are not something you memorize you always have to look them up
The difference electronegativity values of sodium and bromine are; Sodium(Na) 0.9, Bromine(Br) 2.8 thus a difference of 1.9.