chem

• How many different elements are there approximately?

  Around 100 different elements
• What defines an element?

  All atoms in an element are the same
• What does "fixed proportions" mean in a compound?

  Elements are combined in a specific ratio
• What is the proportion of magnesium to sulfur in magnesium sulfide?

  One atom of magnesium to one atom of sulfur
• What is a compound?

  Two or more different elements chemically combined
• What is the appearance of magnesium and sulfur?

  Magnesium is shiny metal; sulfur is yellow solid
• 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
• What is a molecule?

  Elements chemically combined, same or different
• What distinguishes compounds from molecules?

  Compounds have different elements combined
• What elements are found in ammonia?

  Nitrogen and hydrogen
• What is the difference between chlorine and oxygen molecules compared to compounds?

  They are molecules but not compounds
• What is the composition of an oxygen molecule?

  Two oxygen atoms chemically combined
• What does a chemical formula tell us?

  The elements in a molecule and their atom numbers
• What does no number to the right of an element symbol indicate?

  One atom of that element
• What elements are in calcium sulfate?

  Calcium, sulfur, and oxygen
• What happens if you change the number of atoms in a compound?

  You create a different compound
• What does a small number to the right of brackets indicate?

  It multiplies the atoms inside the brackets
• What are the elements and number of atoms in aluminum hydroxide?

  • One atom of aluminum
  • Three atoms of oxygen
  • Three atoms of hydrogen
• What are physical separation techniques used for?

  To separate mixtures
• Can physical separation techniques separate elements in a compound?

  No, they cannot separate elements in a compound
• What is one example of separating elements in compounds?

  Chemical reactions such as reduction
• What does filtration separate?

  An insoluble solid from a liquid
• What does the term 'insoluble' mean?

  It will not dissolve in the liquid
• What happens to silver chloride when mixed with water?

  It does not dissolve
• How do you separate silver chloride from water?

  By using filtration
• What is the filtrate in filtration?

  The liquid that passes through the filter
• What does crystallization separate?

  A soluble solid from a liquid
• What happens when sodium chloride is mixed with water?

  It dissolves to form a solution
• What occurs when sodium chloride solution is left to evaporate?

  Crystals of sodium chloride form
• How can crystallization be sped up?

  By gently heating the solution
• Why should some chemicals not be heated during crystallization?

  They may break down if heated
• What are the key physical separation techniques discussed?

  • Filtration
  • Crystallization
• What are the differences between filtration and crystallization?

  • Filtration: separates insoluble solids from liquids
  • Crystallization: separates soluble solids from liquids
• What are the steps involved in crystallization?

  1. Dissolve the soluble solid in a liquid
  2. Allow the solution to evaporate
  3. Collect the formed crystals
• What physical separation technique is described in the video?

  Simple distillation
• What is the purpose of simple distillation?

  To separate a dissolved solid from a liquid
• What happens to the water during crystallization?

  It evaporates, leaving solid crystals
• What is the first step in simple distillation?

  Evaporate the liquid by heating