Lesson 4.2 Flashcards
In ancient Greek philosophy, the concept of “nothing comes from nothing” is an important idea.
During the 18th century, Aristotle’s adaptation of the concept of the four elements of matter is still dominant.
introduced the concept of phlogiston
German scientist, Georg Ernst Stahl
a universal component of fire that came from a Greek word for inflammable
Every combustible substance contained a specific amount of
Phlogiston
According to this theory, metal calx, when heated with charcoal, produces metal. In this reaction, he explained that the phlogiston of charcoal had united with calx. Therefore, metals are also combustibles.
made the first breakthrough in the study of chemical reaction.
(Late 18th century)
a French chemist, Antoine Lavoisier
Due to his curiosity about the study of combustion and the concept of phlogiston, he first tried to burn phosphorus and sulfur. In his experiment, both gained weight which resulted in both elements gaining weight.
Lavoisier later on concluded that combustion involves the reaction of a metal or an organic substance to a “common air.”
Antoine Lavoisier named this “common air” as
oxygène (oxygen)
In June 1783, Lavoisier reacted oxygen with inflammable air, obtaining “water in a very pure state.”
He concluded that water was not an element but a compound of oxygen and inflammable air or _ as it is known.
Hydrogen
He also decomposed water into oxygen and hydrogen. Both reactions gained the same weight.
Lavoisier, explained the phenomenon in his famous textbook, Trait lmentaire de Chimie, that “… in every operation, an equal quantity of matter exists both before and after the operation.” This concept was also known as
the law of conservation of mass
States that matter can be neither created or destroyed
the law of conservation of mass
revolves to the idea that the total mass of the reactants is the same as the total mass of the products
law of conservation of mass
a french chemist proposed the law of constant composition
Joseph Proust
if a pure compound is broken down into its constituent elements, the masses of the constituents will always have the same proportions, regardless of the quantity or source of the original substance
law of constant composition
studied gases and gaseous mixtures under different external conditions.
Building on Proust’s work, he noted that mathematically discrete manner in which elements combined to form different compounds.
John Dalton
which states that when two elements form a series of compounds, the masses of one that combine with a fixed mass of the other are in the ratio of (small) integers to each other.
law of multiple proportions
Source of Dalton’s Atomic Theory Postulate 1
Elements are composed of extremely small particles, called atoms.
Democritus Idea of an atom
An atom is an indestructible and indivisible particle.
Source of Dalton’s Atomic Theory Postulate 3
Compounds are composed of atoms of more than one element. In any compound, the ratio of the numbers of atoms of any two of the elements present is either an integer or a simple fraction.
Law of Constant Proportion
If a compound is broken down into its constituent elements, the masses of the constituents will always have the same proportions, regardless of the quantity or source of the original substance.
Law of Multiple Proportion
When two elements form a series of compounds, the masses of one that combine with a fixed mass of the other are in the ratio of (small) integers to each other.
Source of Dalton’s Atomic Theory Postulate 4
A chemical reaction involves only the separation, combination, or rearrangement of atoms; it does not result in their creation or destruction.
Law of Conservation of Mass
Matter can be neither created nor destroyed.
