ionic compounds

• 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 overall charge of ionic compounds?

  • Ionic compounds have no overall charge
  • The charges of the ions balance each other out
• What is the formula of sodium chloride?

  NaCl
• What are the charges of the sodium ion and chloride ion?

  The sodium ion has a single positive charge and the chloride ion has a single negative charge
• How many sodium ions are needed to cancel the charge of one chloride ion?

  One sodium ion
• 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
• What is the formula of magnesium iodide?

  MgI2
• What is the formula of lithium carbonate?

  Li2CO3
• How many iodide ions are needed to cancel the charge of one magnesium ion?

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

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

  Ca(OH)2
• How many hydroxide ions are needed to cancel the charge of one calcium ion?

  Two hydroxide ions
• How many nitrate ions are needed to cancel the charge of one magnesium ion?

  Two nitrate ions
• Why do we need to 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 the formula of magnesium nitrate?

  Because it would incorrectly imply there are 32 atoms of oxygen