Element

Chemical Hardness

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Aluminum

2.77 eV

Antimony

3.80 eV

Arsenic

4.5 eV 

Barium

2.9 eV 

Beryllium

4.5 eV 

Bismuth

3.74 eV

Boron

4.01 eV

Bromine

4.22 eV

Cadmium

4.66 eV

Calcium

4.0 eV 

Carbon

5.00 eV

Cesium

1.71 eV

Chlorine

4.68 eV

Chromium

3.06 eV

Cobalt

3.6 eV 

Copper

3.25 eV

Fluorine

7.01 eV

Gallium

2.9 eV 

Germanium

3.4 eV 

Gold

3.46 eV

Hafnium

3.0 eV 

Hydrogen

6.43 eV

Indium

2.8 eV 

Iodine

3.69 eV

Iridium

3.8 eV 

Iron

3.81 eV

Lanthanum

2.6 eV 

Lead

3.53 eV

Lithium

2.39 eV

Magnesium

3.90 eV

Manganese

3.72 eV

Mercury

5.54 eV

Molybdenum

3.1 eV 

Nickel

3.25 eV

Niobium

3.0 eV 

Nitrogen

7.23 eV

Osmium

3.8 eV 

Oxygen

6.08 eV

Palladium

3.89 eV

Phosphorus

4.88 eV

Platinum

3.5 eV 

Potassium

1.92 eV

Rhenium

3.87 eV

Rhodium

3.16 eV

Rubidium

1.85 eV

Ruthenium

3.0 eV 

Scandium

3.20 eV

Selenium

3.87 eV

Silicon

3.38 eV

Silver

3.14 eV

Sodium

2.30 eV

Strontium

3.7 eV 

Sulfur

4.14 eV

Tantalum

3.79 eV

Tellurium

3.52 eV

Thallium

2.9 eV 

Tin

3.05 eV

Titanium

3.37 eV

Tungsten

3.58 eV

Vanadium

3.1 eV 

Yttrium

3.19 eV

Zinc

4.94 eV

Zirconium

3.21 eV

Reference    (Click the button next to a value above to see complete citation information for that entry)

Pearson, Ralph G. "Absolute Electronegativity and Hardness: Application to Inorganic Chemistry." Inorganic Chemistry, volume 27, number 4, 1988, pp 734–740. doi:10.1021/ic00277a030