8Fa Daltons AM

• Atom


  Tiny particle that all matter is made up of
• The idea that all matter comprises tiny particles started


  Over 2400 years ago
• Atomos


  Greek word meaning 'indivisible'
• John Dalton published his atomic theory model


  1805
• Dalton's atomic theory model


  1. All matter is made up of tiny particles called atoms

  2. The atoms in an element are all identical (but each element has its type of atom)

  3. Atoms are indestructible and cannot be created or destroyed

  4. In compounds, each atom of an element is always joined to a fixed number of atoms of other elements

  5. During chemical reactions, atoms rearrange to make new substances
• Difference in atoms


  Gives each element its own, distinct properties
• Physical properties of a substance


  • Color
  • Melting point
  • Boiling point
  • Density
  • Strength
  • Flexibility
  • Conduction of heat
  • Conduction of electricity
• Magnesium


  • Silvery color, shiny solid, melts at 650 degrees Celsius, flexible
• Sulfur


  • Yellow solid, melts at 113 degrees Celsius, brittle
• Carbon


  • Black solid, melts at 3500 degrees Celsius, brittle
• Copper


  • Brownish color, shiny solid, melts at 1083 degrees Celsius, flexible
• Dalton introduced symbols to represent different atoms
• The modern symbols are similar but consist of one or two letters
• All countries use the same symbols so that all scientists can communicate with each other even though they speak different languages