YEAR 9 CHEMISTRY RECAP

YEAR 9 CHEMISTRY RECAP

1. what are chemicals made of

   • ATOMS
     • descriptions of atoms have changed over time
       • bohr model
       • plum pudding
     • structure
       • neutron
         • neutral charge neither postive or negative
         • in the nucleus
         • have a mass of 1 amu
         • the contributed to the atomic mass
         • they prevent electrons and protons from being too attracted and considering the atom
       • protons
         • positive charge
         • in the nucleus
         • have a mass of 1 amu
         • the number of protons defines the atomic number of a atom
       • electrons
         • negative charge
         • orbit the atom
         • changing the number of electrons gives the atom a charge- called a "ion"
         • have no mass

2. CHEMICAL REACTIONS

   • gas being produced
   • physical change
     • nothing unexpected happened
   • chemical changes
     • odour
     • fizzing/ bubbling
     • tempurature change
     • colour change
     • any unexpected changes
     • change in state
   • types of chemical reaction
     • Acid Reaction
       • acid+ base= Salt and water
       • acid+ carbonate= salt+water+ Co2
       • neutralisation
       • decomposition
       • acid+metal=

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