The Atomic Theory of Matter

1
Chapter 2.1

• The Atomic Theory of Matter

2
The History of the Atom

• Greek philosophers in 450 BC
• Atomos- invisible particles
• Plato and Aristotle
• No invisible matter
• Europeans in 17th century
• Reemergence of the atoms as gas particles

3
John Dalton

• 1803
• English school teacher that linked idea of
  elements to atoms

4
Daltons Atomic Theory

• Each element is composed of extremely small
  particles called atoms
• All atoms of a given element are identical to one
  another in mass and other properties, but atoms
  of an element are unique to that element only.
• Atoms of an element are not changed into atoms of
  a different element by chemical reactions they
  are neither created nor destroyed.
• Compounds are formed when atoms of more than one
  element combine, a given compound always has the
  same relative number and kind of atoms.

5
Atom

• Smallest particle of an element that retains the
  chemical identity of the element.

6
Law of Constant Composition

• In a given compound, the relative number and kind
  of atoms are constant.

7
Law of Conservation of Matter

• Total mass of materials present after a chemical
  reaction is the same as the total mass present
  before the reaction.

8
Law of Multiple Proportions

• If two elements A and B combine to form more than
  one compound, the masses of B that combine with a
  given mass of A are in the ratio of small whole
  numbers