John Dalton Research Paper
John Dalton
John Dalton (September 6, 1766 July 27, 1844) was an English chemist and physicist, born at Eaglesfield. He is most well known for his advocacy of the atomic theory and his research into color blindness.
Atomic theory
In 1800 he became a secretary of the Manchester Literary and Philosophical Society, and in the following year he presented the important paper or series of papers, entitled Experimental Essays on the constitution of mixed gases; on the pressure of steam and other vapors at different temperatures, both in a vacuum and in air; on evaporation; and on the thermal expansion of gases.
The second of these essays opens with the striking remark,
"There can scarcely be a doubt entertained respecting the reducibility …show more content…
of all elastic fluids of whatever kind, into liquids; and we ought not to despair of affecting it in low temperatures and by strong pressures exerted upon the unmixed gases further."
After describing experiments to ascertain the pressure of steam at various points between 0 ° and 100°C (32° and 212°F), he concluded from observations on the vapor pressure of six different liquids, that the variation of vapor pressure for all liquids is equivalent, for the same variation of temperature, reckoning from vapor of any given pressure.
In the fourth essay he remarks,
"I see no sufficient reason why we may not conclude that all elastic fluids under the same pressure expand equally by heat and that for any given expansion of mercury, the corresponding expansion of air is proportionally something less, the higher the temperature. It seems, therefore, that general laws respecting the absolute quantity and the nature of heat are more likely to be derived from elastic fluids than from other substances."
He thus enunciated Gay-Lussac's law, stated some months later by Joseph Louis Gay-Lussac. In the two or three years following the reading of these essays, he published several papers on similar topics, that on the absorption of gases by water and other liquids (1803), containing his law of partial pressures.
The most important of all Dalton's investigations are those concerned with the atomic theory in chemistry, with which his name is inseparably associated. It has been proposed that this theory was suggested to him either by researches on ethylene (olefiant gas) and methane (carburetted hydrogen) or by analysis of nitrous oxide (protoxide of azote) and nitrogen dioxide (deutoxide of azote), both views resting on the authority of Thomas Thomson. However, a study of Dalton's own laboratory notebooks, discovered in the rooms of the Lit & Phil[1], concluded that so far from Dalton being led to the idea, that chemical combination consists in the interaction of atoms of definite and characteristic weight, by his search for an explanation of the law of multiple proportions, the idea of atomic structure arose in his mind as a purely physical concept, forced upon him by study of the physical properties of the atmosphere and other gases. The first published indications of this idea are to be found at the end of his paper on the absorption of gases already mentioned, which was read on October 21, 1803 though not published till 1805.
Here he says:
"Why does not water admit its bulk of every kind of gas alike? This question I have duly considered, and though I am not able to satisfy myself completely I am nearly persuaded that the circumstance depends on the weight and number of the ultimate particles of the several gases."
He proceeds to give what has been quoted as his first table of atomic weights, but in his laboratory notebooks there is an earlier one dated 1803 in which he sets out the relative weights of the atoms of a number of substances, derived from analysis of water, ammonia, carbon dioxide, etc. by chemists of the time.
It appears, then, that confronted with the problem of calculating the relative diameter of the atoms of which, he was convinced, all gases were made, he used the results of chemical analysis. Assisted by the assumption that combination always takes place in the simplest possible way, he thus arrived at the idea that chemical combination takes place between particles of different weights, and it was this, which differentiated his theory from the historic speculations of the Greeks.
The extension of this idea to substances in general necessarily led him to the law of multiple proportions, and the comparison with experiment brilliantly confirmed his deduction. It may be noted that in a paper on the proportion of the gases or elastic fluids constituting the atmosphere, read by him in November 1802, the law of multiple proportions appears to be anticipated in the words: "The elements of oxygen may combine with a certain portion of nitrous gas or with twice that portion, but with no intermediate quantity", but there is reason to suspect that this sentence was added some time after the reading of the paper, which was not published till 1805.
Compounds were listed as binary, ternary, etc. in the New System of Chemical Philosophy depending on the number of atoms a compound had in its simplest, empirical form.
He hypothesized the structure of compounds can be represented in whole number ratios. So, one atom of element X combining with one atom of element Y is a binary compound. Furthermore, one atom of element X combining with two elements of Y or vice versa, is a ternary compound. Many of the first compounds listed in the New System of Chemical Philosophy were listed correctly, although others have not.
Dalton used his own symbols to visually represent the atomic structure of compounds.
These have made it in New System of Chemical Philosophy where John Dalton listed a number of elements, and common compounds.
Many of Dalton's ideas were acquired from other chemists at the time, such as Antoine Lavoisier and William Higgins. However, he was the first to put the ideas into a universal atomic theory, which was undoubtedly his greatest achievement. Five main points of Dalton's Atomic Theory
· Elements are made of tiny particles called atoms
· All atoms of a given element are identical
· The atoms of a given element are different from those of any other element
· Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers of types of atoms.
· Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process. A chemical reaction simply changes the way atoms are grouped together.
Unfortunately, Dalton had an additional statement that prevented his theory from being accepted for many years.When atoms combine in only one ratio, " It must be presumed to be a binary one, unless some cause appear to the …show more content…
contrary."
Dalton had no evidence to support this statement from his theory and it caused him to wrongly assume that the formula for water was OH and ammonia was NH. Because of this Dalton's experimental data did not support most of the conclusions he drew from it.
Amazingly, all but two of the statements in Dalton's Atomic Theory are still believed to be true by scientists today.
The statement "Atoms cannot be subdivided, created, or destroyed into smaller particles when they are combined , separated, or rearranged in chemical reactions" is inconsistent with the existence of nuclear fusion and fission, although such processes are nuclear reactions, not chemical reactions. In addition, the statement "All atoms of a given element are identical in their physical and chemical properties" is not precisely true, as the different isotopes of an element have varying numbers of neutrons in their nuclei, though the number of protons remains consistent.
Later years
Various atoms and molecules as depicted in John Dalton's A New System of Chemical Philosophy (1808).
Dalton communicated his atomic theory to Thomson who, by consent, included an outline of it in the third edition of his System of Chemistry (1807), and Dalton gave a further account of it in the first part of the first volume of his New System of Chemical Philosophy (1808).
Death and
legacy
Dalton died in Manchester in 1844 of paralysis. The first attack he suffered in 1837, and a second in 1838 left him with a speech impediment, though he remained able to make experiments. In May 1844 he had another stroke; on July 26 he recorded with trembling hand his last meteorological observation, and on the 27th he fell from his bed and was found lifeless by his attendant. A bust of him, by Chantrey, was publicly subscribed for him and placed in the entrance hall of the Manchester Royal Institution.
In honor of his work with ratios and chemicals that led to the idea of atoms and atomic weights, many chemists and biochemists use the (as of yet unofficial) unit Dalton (abbreviated Da) to denote one atomic mass unit, or 1/12 the weight of a neutral atom of Carbon-12.
John Dalton (September 6, 1766 July 27, 1844) was an English chemist and physicist, born at Eaglesfield. He is most well known for his advocacy of the atomic theory and his research into color blindness.
Atomic theory
In 1800 he became a secretary of the Manchester Literary and Philosophical Society, and in the following year he presented the important paper or series of papers, entitled Experimental Essays on the constitution of mixed gases; on the pressure of steam and other vapors at different temperatures, both in a vacuum and in air; on evaporation; and on the thermal expansion of gases.
The second of these essays opens with the striking remark,
"There can scarcely be a doubt entertained respecting the reducibility …show more content…
of all elastic fluids of whatever kind, into liquids; and we ought not to despair of affecting it in low temperatures and by strong pressures exerted upon the unmixed gases further."
After describing experiments to ascertain the pressure of steam at various points between 0 ° and 100°C (32° and 212°F), he concluded from observations on the vapor pressure of six different liquids, that the variation of vapor pressure for all liquids is equivalent, for the same variation of temperature, reckoning from vapor of any given pressure.
In the fourth essay he remarks,
"I see no sufficient reason why we may not conclude that all elastic fluids under the same pressure expand equally by heat and that for any given expansion of mercury, the corresponding expansion of air is proportionally something less, the higher the temperature. It seems, therefore, that general laws respecting the absolute quantity and the nature of heat are more likely to be derived from elastic fluids than from other substances."
He thus enunciated Gay-Lussac's law, stated some months later by Joseph Louis Gay-Lussac. In the two or three years following the reading of these essays, he published several papers on similar topics, that on the absorption of gases by water and other liquids (1803), containing his law of partial pressures.
The most important of all Dalton's investigations are those concerned with the atomic theory in chemistry, with which his name is inseparably associated. It has been proposed that this theory was suggested to him either by researches on ethylene (olefiant gas) and methane (carburetted hydrogen) or by analysis of nitrous oxide (protoxide of azote) and nitrogen dioxide (deutoxide of azote), both views resting on the authority of Thomas Thomson. However, a study of Dalton's own laboratory notebooks, discovered in the rooms of the Lit & Phil[1], concluded that so far from Dalton being led to the idea, that chemical combination consists in the interaction of atoms of definite and characteristic weight, by his search for an explanation of the law of multiple proportions, the idea of atomic structure arose in his mind as a purely physical concept, forced upon him by study of the physical properties of the atmosphere and other gases. The first published indications of this idea are to be found at the end of his paper on the absorption of gases already mentioned, which was read on October 21, 1803 though not published till 1805.
Here he says:
"Why does not water admit its bulk of every kind of gas alike? This question I have duly considered, and though I am not able to satisfy myself completely I am nearly persuaded that the circumstance depends on the weight and number of the ultimate particles of the several gases."
He proceeds to give what has been quoted as his first table of atomic weights, but in his laboratory notebooks there is an earlier one dated 1803 in which he sets out the relative weights of the atoms of a number of substances, derived from analysis of water, ammonia, carbon dioxide, etc. by chemists of the time.
It appears, then, that confronted with the problem of calculating the relative diameter of the atoms of which, he was convinced, all gases were made, he used the results of chemical analysis. Assisted by the assumption that combination always takes place in the simplest possible way, he thus arrived at the idea that chemical combination takes place between particles of different weights, and it was this, which differentiated his theory from the historic speculations of the Greeks.
The extension of this idea to substances in general necessarily led him to the law of multiple proportions, and the comparison with experiment brilliantly confirmed his deduction. It may be noted that in a paper on the proportion of the gases or elastic fluids constituting the atmosphere, read by him in November 1802, the law of multiple proportions appears to be anticipated in the words: "The elements of oxygen may combine with a certain portion of nitrous gas or with twice that portion, but with no intermediate quantity", but there is reason to suspect that this sentence was added some time after the reading of the paper, which was not published till 1805.
Compounds were listed as binary, ternary, etc. in the New System of Chemical Philosophy depending on the number of atoms a compound had in its simplest, empirical form.
He hypothesized the structure of compounds can be represented in whole number ratios. So, one atom of element X combining with one atom of element Y is a binary compound. Furthermore, one atom of element X combining with two elements of Y or vice versa, is a ternary compound. Many of the first compounds listed in the New System of Chemical Philosophy were listed correctly, although others have not.
Dalton used his own symbols to visually represent the atomic structure of compounds.
These have made it in New System of Chemical Philosophy where John Dalton listed a number of elements, and common compounds.
Many of Dalton's ideas were acquired from other chemists at the time, such as Antoine Lavoisier and William Higgins. However, he was the first to put the ideas into a universal atomic theory, which was undoubtedly his greatest achievement. Five main points of Dalton's Atomic Theory
· Elements are made of tiny particles called atoms
· All atoms of a given element are identical
· The atoms of a given element are different from those of any other element
· Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers of types of atoms.
· Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process. A chemical reaction simply changes the way atoms are grouped together.
Unfortunately, Dalton had an additional statement that prevented his theory from being accepted for many years.When atoms combine in only one ratio, " It must be presumed to be a binary one, unless some cause appear to the …show more content…
contrary."
Dalton had no evidence to support this statement from his theory and it caused him to wrongly assume that the formula for water was OH and ammonia was NH. Because of this Dalton's experimental data did not support most of the conclusions he drew from it.
Amazingly, all but two of the statements in Dalton's Atomic Theory are still believed to be true by scientists today.
The statement "Atoms cannot be subdivided, created, or destroyed into smaller particles when they are combined , separated, or rearranged in chemical reactions" is inconsistent with the existence of nuclear fusion and fission, although such processes are nuclear reactions, not chemical reactions. In addition, the statement "All atoms of a given element are identical in their physical and chemical properties" is not precisely true, as the different isotopes of an element have varying numbers of neutrons in their nuclei, though the number of protons remains consistent.
Later years
Various atoms and molecules as depicted in John Dalton's A New System of Chemical Philosophy (1808).
Dalton communicated his atomic theory to Thomson who, by consent, included an outline of it in the third edition of his System of Chemistry (1807), and Dalton gave a further account of it in the first part of the first volume of his New System of Chemical Philosophy (1808).
Death and
legacy
Dalton died in Manchester in 1844 of paralysis. The first attack he suffered in 1837, and a second in 1838 left him with a speech impediment, though he remained able to make experiments. In May 1844 he had another stroke; on July 26 he recorded with trembling hand his last meteorological observation, and on the 27th he fell from his bed and was found lifeless by his attendant. A bust of him, by Chantrey, was publicly subscribed for him and placed in the entrance hall of the Manchester Royal Institution.
In honor of his work with ratios and chemicals that led to the idea of atoms and atomic weights, many chemists and biochemists use the (as of yet unofficial) unit Dalton (abbreviated Da) to denote one atomic mass unit, or 1/12 the weight of a neutral atom of Carbon-12.