Elements, compounds and mixtures

• What defines an element?

  All atoms are the same
• What happens when magnesium and sulfur atoms are combined?

  They form a compound called magnesium sulfide
• What is a compound?

  Two or more different elements chemically combined
• What does "fixed proportions" mean in a compound?

  Elements are combined in a specific ratio
• How do the properties of compounds compare to their constituent elements?

  Compounds usually have different properties
• What is the appearance of magnesium and sulfur?

  Magnesium is shiny, sulfur is yellow
• What is required to separate a compound back into its elements?

  A chemical reaction
• What characterizes a mixture?

  Different elements or compounds not chemically combined
• How can mixtures be separated?

  Using physical separation techniques
• Name one physical separation technique.

  Filtration
• What is a molecule?

  Any elements chemically combined
• What are examples of compounds mentioned?

  Methane, water, ammonia
• What elements are found in methane?

  Carbon and hydrogen
• What elements are found in water?

  Hydrogen and oxygen
• What elements are found in ammonia?

  Nitrogen and hydrogen
• What distinguishes chlorine and oxygen molecules from compounds?

  They contain the same element combined
• What are the differences between elements, compounds, mixtures, and molecules?

  • Elements: Same atoms, shown in periodic table
  • Compounds: Different elements chemically combined in fixed proportions
  • Mixtures: Different elements or compounds not chemically combined
  • Molecules: Any elements chemically combined, including same elements
• What are the physical separation techniques mentioned?

  • Filtration
  • Distillation
  • Crystallization
  • Chromatography
• What is the chemical formula for hydrogen fluoride?

  HF
• What is the chemical formula for potassium iodide?

  KI
• What is the chemical formula for calcium sulfate?

  CaSO4
• What elements are present in zinc carbonate?

  Zinc, carbon, and oxygen
• What are some examples of chemical formulas discussed?

  • Hydrogen fluoride: HF
  • Potassium iodide: KI
  • Calcium sulfate: CaSO4
  • Magnesium hydroxide: Mg(OH)2
• Help?

  x

  A) CO2

  B) NH3

  C) H2O

  D) NaCl

  E) CO

  F) CaCl2

  G) H2SO4

  H) NaCO3

  I) HCL