elements ,compounds & mixtures

• What should you be able to describe by the end of the video?

  Elements, compounds, mixtures, and molecules
• What are the definitions of an element, compound, mixture, and molecule?

  • Element: All atoms are the same.
  • Compound: Two or more different elements chemically combined in fixed proportions.
  • Mixture: Different elements or compounds not chemically combined.
  • Molecule: Any elements chemically combined, even if they are the same.
• Where are elements shown?

  In the periodic table
• How many different elements are there approximately?

  Around 100
• What does each symbol in the periodic table represent?

  A different element
• What is the symbol for magnesium?

  Capital M followed by lowercase g
• What is the symbol for sulfur?

  Capital S
• What happens when atoms of magnesium and sulfur are chemically combined?

  They form a compound called magnesium sulfide
• What is meant by fixed proportions in a compound?

  It means the elements are combined in a specific ratio
• What is a key fact about the properties of compounds compared to their elements?

  Compounds usually have different properties than the elements they are made from
• What is required to separate a compound back into its elements?

  A chemical reaction
• What is a mixture?

  A combination of different elements or compounds that are not chemically combined
• How can mixtures be separated?

  Using physical separation techniques
• What are some physical separation techniques for mixtures?

  • Filtration
  • Distillation
  • Crystallization
  • Chromatography
• What is a molecule in chemistry?

  A molecule has any elements chemically combined, even if they are the same
• What are examples of compounds that are also molecules?

  Methane, water, and ammonia
• What elements are contained in methane?

  Carbon and hydrogen
• What elements are contained in water?

  Hydrogen and oxygen
• What elements are contained in ammonia?

  Nitrogen and hydrogen
• What is the chlorine molecule composed of?

  Two chlorine atoms chemically combined
• What is the oxygen molecule composed of?

  Two oxygen atoms chemically combined
• What distinguishes molecules from compounds?

  • Molecules can consist of the same element.
  • Compounds consist of different elements.
• Where can you find questions on this topic for revision?

  In the revision workbook