W3

• What are the two main classifications of matter?

  Pure substances and mixtures
• What is a pure substance?

  A pure substance is composed of one kind of matter and cannot be separated into components without breaking chemical bonds.
• What are the two types of pure substances?

  Elements and compounds
• How are elements classified?

  Elements are classified as metals, non-metals, and semi-metals (metalloids).
• What are the properties of metals?

  Metals are lustrous, good conductors of heat and electricity, malleable and ductile, have high densities, and high boiling and melting points.
• What are the properties of non-metals?

  Non-metals are insulators, dull, brittle, have low densities, and low boiling and melting points.
• What defines a compound?


  A compound is composed of two or more elements.
• What are ionic compounds?


  Ionic compounds are formed between metals and non-metals, such as NaCl.
• What are covalent compounds?


  Covalent compounds are formed between two or more non-metals, such as CO2.
• What are the properties of acids?

  Acids contain hydrogen ions (H+), taste sour, change blue litmus paper to red, are chemically active with metals, and are very corrosive, such as HCl.
• What are the properties of bases?

  Bases contain hydroxide ions (OH-), taste bitter, change red litmus paper to blue, and are very corrosive, such as NaOH.
• What defines organic compounds?

  Organic compounds contain carbon or hydrocarbon atoms, such as C6H12O6.
• What defines inorganic compounds?

  Inorganic compounds contain all elements except carbon, such as H2O.
• What is a mixture?

  A mixture is a combination of two or more substances that retains their physical and chemical properties.
• What is a homogeneous mixture?

  A homogeneous mixture, also known as a solution, exists in one phase with combined particles that are very small (less than 1 nm).
• What are the two types of homogeneous solutions?

  Dilute solution (solute < solvent) and concentrated solution (solute > solvent)
• What is a heterogeneous mixture?

  A heterogeneous mixture is not uniform in appearance, and its components can be distinguished from each other.
• What are colloids?


  Colloids are heterogeneous mixtures with particle sizes ranging from 1 nm to 1 µm.
• What are suspensions?


  Suspensions are heterogeneous mixtures with particles large enough to be affected by gravity (greater than 1 µm).
• What are the ways of separating mixtures?

  1. Decantation – used for suspensions, means “to pour”
  2. Filtration – used for colloids/suspensions, uses filter paper
  3. Mechanical methods – used for suspensions, uses devices like tongs or magnets
  4. Extraction – used for solution/colloid, uses extracting agent
• What is the definition of a colloidal system?

  A colloidal system is a type of homogeneous mixture where the particles are dispersed throughout another substance.
• What is the significance of the presence of carbon in organic compounds?

  The presence of carbon or hydrocarbon atoms defines organic compounds.
• What is the significance of the presence of carbon in inorganic compounds?

  Inorganic compounds do not contain carbon.
• How do the properties of acids differ from those of bases?

  Acids taste sour and turn blue litmus paper red, while bases taste bitter and turn red litmus paper blue.