Chemistry (Topic 1, Chapters 1,2,3)

• Elements are arranged into groups based on their electron configuration
• Groups have similar chemical properties because they share the same outermost shell electrons.
• Pure substance: Uniform properties and composition throughout, made up of one type of atom.
• Mixture: A substance made up of two or more elements or compounds that are not chemically combined.

  • varying properties and composition
• Element: A substance that cannot be broken down into simpler substances by chemical means. Made up of one type of atom.
• Compound: Substance with 1 type of molecule (can’t be physically separated)
• Atom: The smallest particle of an element that can exist.
• Molecule: Smallest part of a compound (smallest thing we can call a substance)

  • Has a chemical formula
• Classes of material:

  • Metals: most common type of element with distinctive properties
  • Polymers: consist of many linked, repeated units, with examples like silk, wool, and PVC
  • Ceramics: inorganic, non-metal solids with silicon dioxide as a basic structural unit
  • Composites: combination of different materials with widely different properties, created for specific desired traits or purposes
• Metallic properties include:

  • Conductive: for electricity and heat
  • Lustrous: shiny when cut
  • Sonorous: rings like a bell when struck
  • High melting and boiling points
  • High density
  • Hard: resistant to denting and scratching
  • Malleable: deform under pressure
  • Ductile: can be drawn out into a wire
  • Form cations
• Key characteristic properties:

  • Melting and boiling points
  • Reactivity
  • Hardness
  • Density
• Mixture:

  • Distinct properties dependent on the composition of the substance making up the mixture

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  • Examples include:
  • Wrought iron: low carbon content, used for decorative purposes
  • Medium carbon steel: used for structural purposes
  • Cast iron: very high carbon content, brittle, used for pots
  • Stainless steel variations:
  • High Chromium (20%): used in food processing and pipes
  • 15% chromium: magnetic, very hard, and strong
  • 10% chromium: used for cutting tools and surgical equipment