Interpreting a chemical formula

• What should you be able to do by the end of the video?

  Interpret a chemical formula
• Why do some students find interpreting chemical formulas tricky initially?

  Because it involves understanding symbols and numbers
• What does the periodic table show us?

  All of the different elements
• What does each element in the periodic table have?

  A symbol that starts with a capital letter
• What does a chemical formula tell us?

  The elements in a molecule and the numbers of atoms of each element
• In the chemical formula for hydrogen fluoride, what are the symbols for the elements?

  Hydrogen (H) and Fluorine (F)
• How can you determine the number of atoms of hydrogen in hydrogen fluoride?

  There is no number to the right of hydrogen, indicating one atom
• How can you determine the number of atoms of fluorine in hydrogen fluoride?

  There is no number to the right of fluorine, indicating one atom
• What is the chemical formula for potassium iodide?


  KI
• What elements are present in potassium iodide?

  Potassium and Iodine
• How many atoms of potassium are in potassium iodide?

  One atom of potassium
• How many atoms of iodine are in potassium iodide?

  One atom of iodine
• What is the chemical formula for calcium sulfate?

  CaSO₄
• What elements are present in calcium sulfate?

  Calcium, Sulfur, and Oxygen
• How many atoms of calcium are in calcium sulfate?

  One atom of calcium
• How many atoms of sulfur are in calcium sulfate?

  One atom of sulfur
• How many atoms of oxygen are in calcium sulfate?

  Four atoms of oxygen
• Why is it important that the number of atoms of each element in a compound is fixed?

  Changing the numbers results in a different compound
• What is the difference between calcium sulfate and calcium sulfite?

  They are different compounds due to a change in the number of atoms
• What is the chemical formula for magnesium hydroxide?

  Mg(OH)₂
• What elements are present in magnesium hydroxide?

  Magnesium, Oxygen, and Hydrogen
• How many atoms of magnesium are in magnesium hydroxide?

  One atom of magnesium
• How many atoms of oxygen are in magnesium hydroxide?

  Two atoms of oxygen
• How many atoms of hydrogen are in magnesium hydroxide?

  Two atoms of hydrogen
• What does a small number to the right of brackets in a chemical formula indicate?

  It multiplies the number of atoms inside the brackets
• What elements and number of atoms are in the compound with the formula CuI?

  One atom of copper and one atom of iodine
• What elements and number of atoms are in the compound with the formula FeBr₂?

  One atom of iron and two atoms of bromine
• What elements and number of atoms are in the compound with the formula ZnCO₃?

  One atom of zinc, one atom of carbon, and three atoms of oxygen
• What elements and number of atoms are in the compound with the formula Al(OH)₃?

  One atom of aluminum, three atoms of oxygen, and three atoms of hydrogen
• What are the key components of a chemical formula?

  • Symbols for each element
  • Numbers indicating the quantity of each element
  • Brackets to indicate groups of atoms
• How do you interpret a chemical formula?

  1. Identify the symbols for the elements.
  2. Look for small numbers to determine the number of atoms.
  3. Use brackets to understand groups of atoms.