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# Molecular weight of compounds and chemical elements - calculator.

Using the calculator you can calculate the molecular weight of any chemical compound.
To obtain a result, enter a chemical formula or select elements from the periodic table of elements.

## Molecular weight of compounds and chemical elements

The size of the letters is important

 H

 0
 1
 2
 3
 4
 5
 6
 7
 8
 9

 He
 Li
 Be
 (
 )
 B
 C
 N
 O
 F
 Ne
 Na
 Mg
 Al
 Si
 P
 S
 Cl
 Ar
 K
 Ca
 Sc
 Ti
 V
 Cr
 Mn
 Fe
 Co
 Ni
 Cu
 Zn
 Ga
 Ge
 As
 Se
 Br
 Kr
 Rb
 Sr
 Y
 Zr
 Nb
 Mo
 Tc
 Ru
 Rh
 Pd
 Ag
 Cd
 In
 Sn
 Sb
 Te
 I
 Xe
 Cs
 Ba
 Lan
 Hf
 Ta
 W
 Re
 Os
 Ir
 Pt
 Au
 Hg
 Tl
 Pb
 Bi
 Po
 At
 Rn
 Fr
 Ra
 Akt
 Rf
 Db
 Sg
 Bh
 Hs
 Mt
 Ds
 Rg
 Cn
 Uut
 Fl
 Uup
 Lv
 Uus
 Uuo

 Lanthanides
 La
 Ce
 Pr
 Nd
 Pm
 Sm
 Eu
 Gd
 Tb
 Dy
 Ho
 Er
 Tm
 Yb
 Lu
 Actinides
 Ac
 Th
 Pa
 U
 Np
 Pu
 Am
 Cm
 Bk
 Cf
 Es
 Fm
 Md
 No
 Lr

Select an element from the table

Molecular weight of compounds and chemical elements

Atomic mass, often confused with molar mass - it is a mass:
- one molecule of a chemical compound (e.g. O2, H2O),
- a formal unit of a given compound (e.g., NaCl with an ionic and not a molecular structure),
- one other chemical species (e.g. ion CH3COO).
The molecular weight unit in the SI system is kg. However, much more commonly the molecular weight is expressed in atomic mass units „u” (equal to 1/12 of the atomic mass of the carbon isotope 12C) or „Da” (dalton).

In practice, due to technical difficulties in expressing actual molecular weights, the so-called relative molecular masses - which are calculated as the sum of the relative atomic masses of the atoms that make up it. Relative molecular mass is a dimensionless quantity which should be understood as a multiple of 1/12 of the atomic mass of the carbon isotope 12C.

In the case of populations of molecules with different molecular weights (e.g., polymers, gas mixtures, etc.), the concept of average molecular weight (also called molar) is used. The average molar mass can be calculated as the arithmetic mean or geometric mean weight of individual molecules in the population.

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