History of Atomic Theory
The History of Atomic Theory
Atomos: Not to Be Cut
The atomic model has changed throughout the centuries starting in 400 BC, when it looked like a billiard ball.
Democritus: 400 BC
The question: Can matter be divided into smaller particles? Or can it be infinitely divided?
Matter can be divided into the smallest piece,he named it “atomos”: not to be cut.
Said that atoms were small, hard particles that were all made of the same material but were different shapes and sizes. Atoms were infinite in number, always moving and capable of joining together.
His theory was ignored and forgotten for more than 2,000 years becaus the eminent philosophers of the time, Aristotle and Plato, had a more respected, (and ultimately wrong) theory.
400 BC 1803 1897 1911 1922 Modern
Greek Model, Democritus/Aristotle’s 4 Elements Dalton Model Thomson Model Rutherford Model Bohr Model Wave Model
Dalton’s Model
In the early 1800’s the English Chemist John Dalton performed a number of experiments eventually led to the acceptance of the idea of atoms.
Dalton’s Atomic Theory
Four Points of Dalton’s Theory:
All elements are composed of atoms. Atoms are indivisible and indestructible particles.
Atoms of the same element are exactly alike.
Atoms of different elements are different.
Compounds are formed by the joining of atoms of two or more elements.
3 Laws that came about because of Dalton’s Theory:
Law of Definite Proportions: Joseph Proust, French Chemist: Stated that different samples of the same compound always contain its’ constituent elements in the same proportion by mass. - If you get water from anywhere it is all going to be the same. It is going to be H20.
Law of Multiple Proportions: John Dalton: Stated that if two elements can combine to form more than one compound the masses of one element can combine with a fixed mass of the other element are in ratios of small whole numbers.- CO2 & CO = Ratio: 1:2 &
Atomos: Not to Be Cut
The atomic model has changed throughout the centuries starting in 400 BC, when it looked like a billiard ball.
Democritus: 400 BC
The question: Can matter be divided into smaller particles? Or can it be infinitely divided?
Matter can be divided into the smallest piece,he named it “atomos”: not to be cut.
Said that atoms were small, hard particles that were all made of the same material but were different shapes and sizes. Atoms were infinite in number, always moving and capable of joining together.
His theory was ignored and forgotten for more than 2,000 years becaus the eminent philosophers of the time, Aristotle and Plato, had a more respected, (and ultimately wrong) theory.
400 BC 1803 1897 1911 1922 Modern
Greek Model, Democritus/Aristotle’s 4 Elements Dalton Model Thomson Model Rutherford Model Bohr Model Wave Model
Dalton’s Model
In the early 1800’s the English Chemist John Dalton performed a number of experiments eventually led to the acceptance of the idea of atoms.
Dalton’s Atomic Theory
Four Points of Dalton’s Theory:
All elements are composed of atoms. Atoms are indivisible and indestructible particles.
Atoms of the same element are exactly alike.
Atoms of different elements are different.
Compounds are formed by the joining of atoms of two or more elements.
3 Laws that came about because of Dalton’s Theory:
Law of Definite Proportions: Joseph Proust, French Chemist: Stated that different samples of the same compound always contain its’ constituent elements in the same proportion by mass. - If you get water from anywhere it is all going to be the same. It is going to be H20.
Law of Multiple Proportions: John Dalton: Stated that if two elements can combine to form more than one compound the masses of one element can combine with a fixed mass of the other element are in ratios of small whole numbers.- CO2 & CO = Ratio: 1:2 &