Daltons Theory, Metals/NonMetals, Periodic Table(8F Science)

• Dalton's atomic theory


  • All matter is made up of tiny particles called atoms
  • Atoms are indestructible, and cannot be created, or destroyed
  • The atoms in an element are all identical
  • In compounds, each atom of an element is always joined to a fixed number of atoms of the other elements
  • During chemical reactions, atoms rearrange, to make new substances
• Chemical reaction


  • Hydrogen + Chlorine → Hydrogen chloride
• No atoms are lost or gained so the mass of the reactants is equal to the mass of the products
• Word equation


  Reactants → Products
• Signs of a chemical reaction

  • Colour change
  • Gas produced
  • Solid formed from solution
  • Energy change
• Elements


  Tiny particles that cannot be broken down into simpler substances by chemical means
• Element symbols


  Agreed by scientists, either a single or double letter, first letter is always capital
• Chemical formula


  Tells you the number of atoms of each element that are joined in its molecules, or the ratio of atoms of each element in the compound
• Metals


  • High melting points
  • Solids at room temperature
  • Strong and flexible
  • Malleable
  • Shiny (when polished)
  • Good conductors of heat and electricity
• Non-metals


  • Low melting point
  • Brittle (when solid)
  • Not shiny
  • Poor conductors of heat and electricity
• Chemical properties


  e.g. flammability, pH, reaction with acid
• Physical properties


  e.g. melting point, boiling point, density
• Periodic table


  • Arranges elements so that those with similar properties are in the same vertical group
  • Allows us to spot trends and patterns
• Down the groups


  Physical and chemical properties often show a trend
• Across the periods


  Physical and chemical properties often show a trend
• Alkali metals


  • React with water, forming an alkaline solution and hydrogen
  • Reactivity increases down the group
• Halogens


  • Reactive non-metals
  • Reactivity decreases down the group
• Noble gases


  • Very unreactive gases
  • Do not form compounds easily
• Metal oxides


  Tend to form alkaline solutions
• Non-metal oxides


  Tend to form acidic solutions
• Elements are arranged by increasing atomic mass within each group (column).
• The periodic table is an arrangement of elements based on their atomic number.
• The periodic table is divided into groups or columns.
• Group 1 elements are called alkali metals.
• Group 7 elements are called halogens.