Sc2a- Mixtures

• What is an element?

  Contains only one type of atom
• What is a mixture?

  Contains more than one type of element not chemically bonded together
• What is a compound?

  Contains more than one type of element, chemically combined
• What is a pure substance?

  A substance that contains only one element or compound, with nothing foreign added
• What type of melting point does a pure substance have?

  It has a sharp melting point at the same temperature, and is consistent
• What type of melting point does impure substances/ mixtures have?

  They melt over a range of temperatures as there is different substances with different melting points within it
• Describe what happens to atoms at a pure substance’s melting point

  Atoms will have a constant appearance, colour and density
• How to use a heating curve to identify a melting point

  -Pure substances will all melt at the same temperature and have a sharp melting point until all the substance has changed state

  • A mixture melts over a range of temperatures (because there is more than one substance, so there is different melting points) which is why mixtures do not have fixed, sharp melting points