AAT Bioquest

What are the limitations of Dalton's atomic theory?

Posted December 13, 2022


Limitations of Dalton’s Atomic Theory include the following: 

  • It has been proved that an atom can be further subdivided into subatomic particles such as protons, electrons, and neutrons. This disproves Dalton’s assumption that atoms are indivisible. 
  • Dalton’s theory states that atoms of the same element are identical to each other. However, further studies indicate that atoms of some elements vary in their density and mass. Chlorine is one such atom that has two isotopes with mass numbers 35 and 37. 
  • According to Dalton’s theory, atoms of different elements are different in all respects. However, this does not account for isobars, which refers to different elements that share the same mass number. For example, calcium and argon are isobars with each having an atomic mass of 40 amu. 
  • In certain complex organic compounds such as sugar (C11H22O11), the individual elements do not combine in a simple whole number ratio. This disproves Dalton’s postulate that atoms of different elements combine in simple, whole-number ratios to form compounds. 
  • Another limitation of Dalton’s theory is that it does not account for allotropes such as diamond and graphite, both of which have completely different properties although they both contain only carbon. 
Additional resources

Dalton’s and Amagat’s laws fail in gas mixtures with shock propagation

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