Chemistry

Chemistry

1. States of matter

   • Solid- A solid holds or keeps its shape. The particles are tightly packed together and has minimal movement
   • Liquid- forms a pool not a pile. Takes shape of any container it is put in. Paricles are less tightly packed and move around a bit
   • Gas- Will escape from any container that is not sealed. The particles are spread out ansd can move around a lot
   • 4 processes: Melting evaporation condensing freezing
   • Condensing is from a gas to liquid.
   • Freezing is liquid to solid
   • Melting is solid to liquid
   • Evaporation- is when a liquid goes to gas

2. Separating mixtures

   • Pure substance is made up of the same atoms
   • A mixture contains elements and/or compounds that are not chemically joined together. You can use physical processes to separate them into different substances
   • Chromotography- separates liquids of different colours
   • Distillation- separates liquids with different boiling points
   • Filteration- separates a solid from liquid

3. Pure substances have a sharp melting point. Mixtures have a range of melting points

   • Filters can be used to separate some mixtures. They let smaller pieces or liquids through but trap bigger pieces or insoluble substances
   • Inks, paints and foods often contain mixtures of coloured compounds. Chromatography is used to find out which coloured compounds a mixture contains
   • Rf value
     • Rf stands for retention factor. We can work out the Rf value using this equation
       • Rf- Distance moved by the spot/ Distance moved by the solvent

4. Distillation

   • Distillation can be used to separate compounds with different boiling points. This includes a liquid from dissolved solids and different liquids
   • Simple distillation evaporates the solvent away leaving the solute. The vapour is then condensed and collested

5. Atomic structure

   • Protons have a positive charge
   • Neutrons have no charge at all
   • Electrons have a negative charge
   • Atoms in element always have equal numbers of protons and electrons and so have no overall charge, because charges cancel each other out
   • Isotopes- More atoms of the same element, they have the same atomic number but have different mass nuber
   • Top number is the mass number. And the bottom number is the atomic number.