Formula of Ionic Compounds

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

  The formula of an ionic compound using the charges on ions
• What is the key rule for ionic compounds regarding charges?

  The charges on the ions must cancel out to leave an overall charge of zero
• What is the characteristic of all ionic compounds regarding overall charge?

  • Ionic compounds have no overall charge
  • The charges of the ions balance each other out
• How do you determine the formula of sodium chloride?

  By recognizing that one sodium ion cancels out the charge of one chloride ion
• What is the formula of sodium chloride?

  NaCl
• What happens if there are two sodium ions in sodium chloride?

  The compound would have an overall +1 charge, which is not allowed
• What is the formula of sodium oxide?

  Na2O
• How many sodium ions are needed to cancel the charge of one oxide ion?

  Two sodium ions are needed
• What is the formula of magnesium iodide?

  MgI2
• How many iodide ions are needed to cancel the charge of one magnesium ion?

  Two iodide ions are needed
• What is the formula of lithium carbonate?

  Li2CO3
• How many lithium ions are needed to cancel the charge of one carbonate ion?

  Two lithium ions are needed
• What is the formula of calcium hydroxide?

  Ca(OH)2
• Why do we use brackets in the formula of calcium hydroxide?

  To indicate that the subscript applies to the entire hydroxide ion
• What is the formula of magnesium nitrate?

  Mg(NO3)2
• Why can't we simply write a 2 next to the nitrate ion in magnesium nitrate?

  Because it would incorrectly imply there are 32 atoms of oxygen
• What types of questions will you not see in an exam regarding ionic compounds?

  • No questions more difficult than those shown in the video
  • Focus on basic ionic compound formulas
• What should you be able to do after watching the video?

  Determine the formula of an ionic compound using the charges on ions