HISTORY OF THE ATOM

DEMOCRITUS (400 BC)

• Proposed that matter was made up of tiny, indestructible particles
• These particles he named "Atomos" (atoms)
• He was known as the laughing philosopher
• Was a philosopher and did not do experiments
• Born in Greece

JOSEPH BLACK (1728-1799)

• Discovered that air is not an element
• During his experiment he put acid on chalk and breathed it in but in result he passed out because instead of breathing in pure O2 he breathed in pure CO2.
• Scottish

JOHN DALTON (1766-1844)

• Atoms are indivisible and indestructible
• All atoms of a given element are identical in mass and properties
• Compounds are consisted of two or more elements
• Chemical reactions are the rearrangement of atoms
• Lived in England

ANTOINE LAVOISIER (1743-1784)

• Proposed that mass can not be created nor destroyed
• Helped co-discover, recognize, and name oxygen and hydrogen
• Lived in Paris, France