Wk.#7: Chemistry – Changes & Reactions

Week #7: Chemistry – Changes & Reactions


  • Recognize examples of physical and chemical changes
  • Recognize symbols indicating dangers or hazardous materials
  • Find symbols representing elements on the Periodic Table
  • Use a pH indicator to identify acids and bases
  • Manipulate experimental variables and predict outcomes
  • Practice lab safety while handling chemicals


  • Learners discussed examples of physical and chemical changes.
  • Learners looked for clues to decode a message that used the Periodic Table of Elements as the key.
  • Learners made a pH indicator from red cabbage and used it to test common kitchen materials as being acidic or basic (including baking soda, cream of tartar, laundry soap, dish soap, borax, lemon soda, vinegar). They then combined mixtures and observed how the pH
  • Learners conducted an experiment with hydrogen peroxide and yeast, repeating the experiment with the amount of yeast as constant and the concentration of peroxide as either 3% or 9% concentration. They then explored how mixing in water or soap would change the observed reaction.

Questions to Discuss

  • What are two examples of a physical change to a material?
  • What are two examples of a chemical change to a material?
  • What are two properties you can learn about an element by looking it up on the Periodic Table?
  • What were some of the reactions you observed when you mixed the indicator and materials together?
  • What are two ways that you could identify if a clear liquid was water or vinegar without tasting it?
  • What reactions did you observe when you mixed the yeast with the hydrogen peroxide?
  • What did you change or add to your experiment to improve the reaction of the yeast and hydrogen peroxide?
  • Why do you think it’s important that a chemist should label the materials that they are using?

Things to Try at Home

  • Table salt (sodium chloride – NaCl) is a compound of the highly reactive elements of the alkali metal sodium (Na) and the corrosive gas chlorine (Cl). Look up three other examples of common useful chemical compounds and what elements they are made of.
  • The Periodic Table of Elements is called that because it organized things according to similar properties. Find a table (or create one) to organize things into families (video games, food, books, sports, or other) and choose how to arrange those families should be ordered (most fun games – least fun, smallest fruit to largest, fewest pages to most).
  • Make a song, poem, or poster about an element from the Periodic Table that includes fun facts about the element, something it is used for, and what phase state you could find it in (solid, liquid, or gas).
The Periodic Table of Elements Song
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