atomic structure C1

atomic structure C1

1. Atoms

   • there are about 100 different elements on the periodic table
   • each element is made of one type of atom
   • the table is arranged in columns called groups; these usually have similar properties
   • atoms have a tiny nucleus surrounded by electrons
   • when elements react with others they create compounds

2. chemical equations

   • word equations give the names of the reactants and products
     • a balanced symbol equation has the same no. of each element on each side
   • the law of conservation of mass
     • no atoms are lost or made during any chemical reactions
       • sometimes it seems as though some have been destroyed but this is usually when the product is a gas so is may escape into the air

3. separating mixtures

   • filtrations: separates substances insoluble in a substance from soluble ones
   • crystallisation: separates a soluble solid from a solvent
   • distillation: separates a solvent from a soluble solids dissolved in the solvent

4. fractional distillation and paper chromatography

   • this is a way to separate miscible liquids
   • the liquids have different boiling points
     • this is a way to separate ethanol from a fermented mixture in the drinks industry
   • paper chromatography is a way to separate substances from mixtures in a solution
     • its a way to separate food colourings

5. history of the atom

   • 1. the ancient greeks had ideas
     • 2. dalton said; tiny had spheres
       • 3. Thomson discovered tiny negatively charged particles
   • 4. he's proposed the plum pudding model; cloud of positive with small eletrons
     • 5. geiger and marsden; fired alpha particles at gold foil, found small positive charge at centre of atom
       • 6. in nuclear model; the small electrons orbit the nucleus made of positive and neutral particles

6. Structure of the atom

   • nucleus; protons and neutrons
   • orbiting; electrons
   • atomic number; amount of electrons and protons
   • mass number; neutrons + protons

7. tons, atoms and isotopes

   • an ion is a charged atom
     • atoms are incredibly small
       • atoms with a different number of neutrons are called isotopes
         • they have same chemical but different physical properties
   • + electron = negative charge
     • - electron = positive charge

8. electronic structures

   • electrons are arranged around the nucleus in shells
     • the shells can hold; 2,8,8,18,18...
   • atoms in the same group have the same amount of electrons in their outer shell
     • this means they all react a similar way chemically
       • group 0 atoms have full outer shells so are very unreactive