Chemistry paper 1

• Okay let's try and go through all of the chemistry that you need to know for GCSE chemistry paper 1 and we're going to be covering atoms bonding constitutive chemistry chemical changes and energy changes
• Don't forget you can download the pdf version of this from science shorts net link in description
• This is the hardest paper because there is so much stuff you need to know for it not only that some of the questions you have involved quite a bit of tricky math
• It's not enough just to learn all this stuff the best way of getting good at GCSE science is actually having a go at questions
• Atom


  Something that can't be broken down or split into its constituents or smaller bits by chemical means
• Compound


  Two or more types of atoms chemically bonded together
• Mixture


  Different types of atoms or compounds not chemically bonded together
• Chromatography


  1. Filter paper with a dot of the mixture about a centimeter above the water line

  2. Filter paper is dipped in the water

  3. Water gets drawn up to paper due to capillary action and drags particles of the mixture with it

  4. Particles that end up the highest on the paper are the lighter particles
• RF value


  Retention factor, calculated by doing how far the solute has gone up the paper divided by how far the solvent has gone
• Filtration


  1. Removes insoluble particles like sand from water

  2. Filter paper in a funnel, put the stuff in the top and let the water drip through
• If this was salt water you'd still end up with salt in the water at the bottom because the salt is actually dissolved in the water
• Distillation


  1. Separates a solid from a solvent like salt from water

  2. Heat the mixture or the solution, the water evaporates and then we re condense it using a condenser tube

  3. The water gets collected in a beaker leaving just the salt behind in the flask
• Nucleus


  The bits in the middle of an atom that make it up, containing neutrons and protons
• Electrons


  Orbit around the outside of the nucleus
• Protons


  Have a charge of +1
• Electrons


  Have a charge of -1
• Neutrons


  Have no charge
• Atoms have to have the same number of protons as electrons so that they are neutral
• Ion


  An atom that has lost or gained electrons, so it has an overall positive or negative charge
• Periodic table columns


  • 1 2 (gap) 3 4 5 6 7 8 or 0
• Column/Group


  Tells you how many electrons are in the outer shell
• Period


  Tells you how many shells of electrons an element has
• Hydrogen is a bit special, only needs 2 electrons in its outer shell to be full
• Metals vs Nonmetals


  • Metals are to the left of the staircase, nonmetals are to the right
• Metals


  Electron donators, lose electrons when they bond
• Nonmetals


  Electron acceptors
• Groups


  • Group 1 - Alkali metals
  • Group 7 - Halogens
  • Group 8 or 0 - Noble gases
• Alkali metals


  Get more reactive as you go down the group, because the outer electron is further from the nucleus
• Halogens


  Get less reactive as you go down the group, because the outer shell is further from the nucleus
• Noble gases


  Very unreactive, have a full outer shell
• Atomic number


  Number of protons in the nucleus
• Mass number


  Number of protons plus neutrons
• Electron shell filling


  2 8 8 2
• We only really care about the first 20 elements, up to calcium, because it gets messy after that
• Chlorine


  Atomic number 17, so has 17 protons and 17 electrons, with 7 in the outer shell
• Atoms want either a full or empty outer shell, never in between
• Ionic bonding


  Metals bond to nonmetals, the metal donates electrons to the nonmetal
• Ionic compound


  • Magnesium chloride - Mg2+ and Cl-
• Dot and cross diagram for ionic bonding


  Metal has empty outer shell, nonmetal has crosses for electrons and dots for donated electrons
• Ionic compounds


  • Have high melting and boiling points, are soluble in water, can conduct electricity when molten or in solution