Atoms, Molecules, and Ions
2.1 Early history of Chemistry
Democritus coined the term “atomos”
Robert Boyle was the first to run systematic experiments; he explained
quantitative behaviour of gasses.
Georg Stahl stated that the saturation of “phlogiston” justified lack of
flames in a vacuum, whereas Joseph Priestley stated that dephlogisticated
air lead to fire.
2.2 Fundamental Chemical Laws
Antoine Lavoisier ran extensive experiments that involved measurements,
leading to the law of conservation of mass. Publish first modern chemistry
book Elementary Treatise on Chemistry.
Joseph Proust showed through experiments that a given compound always
contains exactly the same proportion of elements by mass. Later known as,
law of definite proportions.
John Dalton was inspired by Joseph Proust and further thought about the
idea of atoms in order to explain proportions, from which he reasoned,
when two elements form a series of compounds, the ratio of the masses of
the second element that combine with 1 gram of the first elements can
always be reduced to small whole numbers. This is known as Law of
multiple proportions.
Dalton induced from these laws that elements are to be made up of certain
types of atoms and compounds were simply combinations of such.
2.3 Dalton’s atomic theory
John Dalton published his book “A new system of Chemical Philosophy” in
which he postulated:
- Each element is made up of tiny particles known as atoms.
- Atoms of a given element are identical, Atoms from different elements
are different.
- Chemical compounds are formed when atoms combine with one
another. A given compounds always has the same relative numbers and
types of atoms.
- Chemical reaction involves reorganization of the atoms – changes in the
way they are bound together.
2.1 Early history of Chemistry
Democritus coined the term “atomos”
Robert Boyle was the first to run systematic experiments; he explained
quantitative behaviour of gasses.
Georg Stahl stated that the saturation of “phlogiston” justified lack of
flames in a vacuum, whereas Joseph Priestley stated that dephlogisticated
air lead to fire.
2.2 Fundamental Chemical Laws
Antoine Lavoisier ran extensive experiments that involved measurements,
leading to the law of conservation of mass. Publish first modern chemistry
book Elementary Treatise on Chemistry.
Joseph Proust showed through experiments that a given compound always
contains exactly the same proportion of elements by mass. Later known as,
law of definite proportions.
John Dalton was inspired by Joseph Proust and further thought about the
idea of atoms in order to explain proportions, from which he reasoned,
when two elements form a series of compounds, the ratio of the masses of
the second element that combine with 1 gram of the first elements can
always be reduced to small whole numbers. This is known as Law of
multiple proportions.
Dalton induced from these laws that elements are to be made up of certain
types of atoms and compounds were simply combinations of such.
2.3 Dalton’s atomic theory
John Dalton published his book “A new system of Chemical Philosophy” in
which he postulated:
- Each element is made up of tiny particles known as atoms.
- Atoms of a given element are identical, Atoms from different elements
are different.
- Chemical compounds are formed when atoms combine with one
another. A given compounds always has the same relative numbers and
types of atoms.
- Chemical reaction involves reorganization of the atoms – changes in the
way they are bound together.
