O Dalton Atomic Model presents substances as being made up of small particles called atoms. The atom proposed by Dalton would be a spherical, massive and indivisible particle.
In his postulates, the scientist claimed that atoms of different elements have different properties, but all atoms of the same element are exactly the same.
In chemical changes, the atom participates as a whole. Atoms do not change when they form chemical compounds. They cannot be created or destroyed.
The Study of Atmosphere
It was the systematic study of the atmosphere that led Dalton to the atomic theory of matter. The scientist had taken hundreds of air samples from various places in England, from mountains, valleys, city and countryside.
After the analysis, he concluded that the air had the same composition. This worried Dalton.
Why doesn't the heavier carbon dioxide stay at the bottom? Why were the gases so mixed?
Dalton, who was not a great experimenter, tried to verify the matter in the laboratory. He placed a heavy gas vial on the table and inverted a light gas vial over it so that the mouths of the vials touched. Soon the gases were fully mixed.
Dalton explained this fact by stating what came to be known as partial pressure theory:
"The particles of a gas do not repel those of another gas, but only those of its own kind."
This led to the assumption that a gas consists of very small particles separated from each other by great distances.
Dalton defined chemistry and chemical analysis. According to him, all chemistry can do is separate particles from one another, or join them together.
These particles were for him the indestructible portions of matter that made up all substances. And, in fact, they remained indestructible until the discovery of radioactivity and the breaking of atoms.
Knowing how much of each substance must go into a process to produce the required amount of a compound is of paramount importance for any chemist.
Through trial and error, it was Dalton who used the data thus collected to obtain the relative weight of the final particles. called today from atomic weight.
Dalton's mistakes were the result of faulty laboratory techniques. He established their atomic weights by assigning weight one to the hydrogen particle.
He said, that a "simple" of hydrogen combines with a "single" of oxygen and produces a compound of water.
The weight of oxygen is seven times that of hydrogen, so the relative weight of the oxygen particle is seven times that of hydrogen.
He didn't know that it takes two hydrogen atoms to combine with oxygen, and he made a mistake when weighing the substances.
In order to explain his "simple" combination, he drew small circles with different central symbols for the atom of each element. Dalton's atomic model, or Dalton's atomic theory, was soon accepted by all his fellow scientists.
Learn more about Atom.
Who was Dalton?
John Dalton was an English chemist, meteorologist and physicist, born in Eaglesfield, England, on September 6, 1766, and died in 1844.
He was elected to the Academy of Sciences. He won the medal of the Royal Society of England in 1826. He discovered the color vision anomaly, as he had suffered from this defect, now called color blindness.
Gain more knowledge with the following contents:
- Atomic Models
- Evolution of Atomic Models
- Thomson Atomic Model
- Rutherford Atomic Model
- Bohr's Atomic Model
- Exercises on Atomic Models
