Interpretating a Chemical Formula

• What does a chemical formula represent?

  A chemical formula represents the elements in a molecule and the number of atoms of each element.
• Why do chemical symbols start with a capital letter?

  To indicate the symbols of elements in the periodic table.
• What does a small number to the right of a chemical symbol indicate?

  It indicates the number of atoms of that element in the compound.
• How can you determine the number of atoms of an element in a compound if there is no small number present?

  There is one atom of that element in the compound.
• What elements and how many atoms are in the compound potassium iodide?

  • Elements: Potassium, Iodine
  • Atoms: 1 atom of Potassium, 1 atom of Iodine
• What elements and how many atoms are in the compound calcium sulfate?

  • Elements: Calcium, Sulfur, Oxygen
  • Atoms: 1 atom of Calcium, 1 atom of Sulfur, 4 atoms of Oxygen
• What does the presence of brackets in a chemical formula indicate?

  It indicates that the numbers outside multiply all the elements inside the brackets.
• What elements and how many atoms are in the compound magnesium hydroxide?

  • Elements: Magnesium, Oxygen, Hydrogen
  • Atoms: 1 atom of Magnesium, 2 atoms of Oxygen, 2 atoms of Hydrogen
• What elements and how many atoms are in the compound copper iodide?

  • Elements: Copper, Iodine
  • Atoms: 1 atom of Copper, 1 atom of Iodine
• What elements and how many atoms are in the compound iron bromide?

  • Elements: Iron, Bromine
  • Atoms: 1 atom of Iron, 2 atoms of Bromine
• What elements and how many atoms are in the compound zinc carbonate?

  • Elements: Zinc, Carbon, Oxygen
  • Atoms: 1 atom of Zinc, 1 atom of Carbon, 3 atoms of Oxygen
• What elements and how many atoms are in the compound aluminum oxide?

  • Elements: Aluminum, Oxygen, Hydrogen
  • Atoms: 1 atom of Aluminum, 3 atoms of Oxygen, 3 atoms of Hydrogen
• What happens if the number of atoms of an element in a compound is changed?

  It results in a different compound.