The World According To Dalton Essay, Research Paper
John Dalton
John Dalton (1766-1844), was a British chemist and physicist, who developed the
atomic theory upon which modern physical science is based. Dalton was born on September 6,
1766, in Eaglesfield, Cumberland County, England. He was the son of a weaver and was
initially educated by his father and then at Quaker school in his hometown, where he began
teaching at the age of 12. In 1781 he moved to Kendal, where he headed up a school with his
cousin and his older brother. He went to Manchester in 1793 and spent the rest of his life there
as a teacher, first at New College and later as a private tutor. In 1804 and 1809 Dalton was
invited to teach at the Royal Institution in London. He was made a member of the Royal Society
in 1822 and was awarded the society’s gold medal in 1826. In 1830 Dalton became one of the
eight foreign associates of the French Academy of Sciences. Dalton died in Manchester on July
27, 1844.
Dalton’s most important contribution to science was his theory that matter is composed
of atoms of differing weights and combine in simple ratios by weight, also known as the atomic
theory This theory, which Dalton first advanced in 1803, is the cornerstone of modern physical
science. In 1808 Dalton’s ‘A New System of Chemical Philosophy’ was published. In this book
he listed atomic weights of many known elements relative to the weight of hydrogen. His
weights were not totally accurate but they did form the basis for the modern periodic table.
Dalton rooted his atomic theory through the study of the physical properties of atmospheric air
and other gases. During this study he discovered the law of partial pressures of mixed gases,
known as Dalton’s law, that is, “The total pressure exerted by a mixture of gases is equal to the
sum of the separate pressures that each of the gases would exert if it alone occupied the whole
volume.”
DALTON’S TABLE OF ATOMIC WEIGHTS
1. Hydrogen, its relative weight 1
2. Azote 2
3. Carbone or charcoal 5
4. Oxygen 7
5. Phosphorous 9
6. Sulphur 13
7. Magnesia 20
8. Lime 23
9. Soda 28
10. Potash 42
11. Strontites 46
12. Barytes 68
13. Iron 38
14. Zinc 56
15. Copper 56
16. Lead 95
17. Silver 100
18. Platina 100
19. Gold 140
20. Mercury 167
DALTON’S ATOMIC THEORY
1. All matter consists of tiny particles.
2. Atoms are indestructible and unchangeable. Atoms of an element cannot be created,
destroyed, broken into smaller parts or transformed into atoms of another element.
3. Elements are characterized by the mass of their atoms. All atoms of the same element
have identical weights, atoms of different elements have different weights.
4. When elements react, their atoms combine in simple, whole-number ratios.
Although some details of Dalton’s original atomic theory are known to be incorrect, the
main concepts of the theory – those being the seperation and union as well as characteristics of
atoms – are the foundations of modern physical science.