Paper 1

• Topics covered in AQA GCC Chemistry Paper 1

  • Atoms
  • Bonding
  • Quantitative Chemistry
  • Chemical and Energy Changes
• Substances

  Stuff are made of atoms
• Elements


  Represented in the periodic table by a symbol
• Compound

  A substance that contains two or more different types of atoms chemically bonded together
• Compound


  • Water (H2O)
• Chemical reactions

  Atoms change what they're bonded to and how they're bonded
• Chemical reactions

  Atoms are not created or destroyed
• Chemical equations


  Must have the same number of each type of atom on both sides
• Chemical equations


  Equations must be balanced
• Physical processes

  No new substances are being made
• A mixture is any combination of different types of elements and compounds that aren't chemically bonded together
• Mixture

  • Air, saltwater
• Filtration

  Used to separate large insoluble particles from a liquid
• Crystallization


  Leaves a solid dissolved in a liquid behind after evaporating the solvent
• Distillation

  Heating a solution and cooling the gas to condense it back into a liquid
• Fractional distillation


  Separating different liquids of a mixture based on boiling points
• Solid, liquid, and gas are the three main states of matter
• Melting or evaporating a substance


  Requires supplying energy to overcome forces of attraction between particles
• Physical changes do not create new substances
• Chemical reaction equations indicate the state of substances with state symbols
• Plum pudding model of the atom

  Atoms made up of positive charge with electrons dotted around it
• Nucleus


  Discovered by Ernest Rutherford, contains positive charges and is incredibly small
• Electrons


  Exist in shells or orbitals
• Neutrons and protons


  Discovered by James Chadwick, neutrons are neutral charges, protons are positive charges
• B later discovered that electrons exist in shells or orbitals
• James Chadwick discovered that the nucleus must also contain some neutral charges he called them neutrons while the positive charges are called protons
• Protons and electrons have equal and opposite charges


  Protons are plus one and electrons are minus one relatively speaking
• Neutrons


  Have a charge of zero
• Protons and neutrons


  Have essentially the same mass, so they have a relative mass of one
• Electrons


  Are very light in comparison, so they have a mass of zero or just very small depending on the situation
• Periodic table


  Tells us everything we need to know about an atom
• Atomic number


  Number of protons in the nucleus, determines the element
• Every atom has an overall neutral charge, so they must have the same number of electrons as protons
• If an atom gains or loses electrons, it's now called an ion, not an atom
• Mass number or relative atomic mass (RAM)


  Tells how many protons and neutrons are in the nucleus
• Isotopes are atoms of the same element but with different numbers of neutrons
• Periodic tables sometimes show the average mass for all isotopes of an element found in the world
• Chlorine gas has a relative abundance of 75% with a mass of 35 and 25% with a mass of 37
• To find the average mass, we add up the total masses of all isotopes and divide by 100
• Chlorine's average relative atomic mass is 35.5