Chemical Formulae of ions

• What do chemists use to represent elements and compounds?

  Symbols and formulae
• What do word equations and balanced chemical equations represent?

  The changes that happen in chemical reactions
• What is an ion?

  An electrically charged particle formed when an atom or molecule gains or loses electrons
• How is an ion formed?

  When an atom or group of atoms loses or gains electrons
• What is the charge of an electron?

  Negative
• What does the superscript in a chemical formula indicate?

  The number and sign of its electrical charges
• What are the names and formulas of some common ions?

  • Sodium: Na⁺ (One positive)
  • Magnesium: Mg²⁺ (Two positive)
  • Chloride: Cl^- (One negative)
  • Oxide: O^2- (Two negative)
• How can the formula of an ionic compound be predicted?

  Using the formulae of its ions
• What must the numbers of ions in a formula provide?

  An equal number of positive and negative charges
• What are the formulas and electrical charges of some common ionic compounds?

  • Sodium chloride: NaCl (One positive, one negative)
  • Sodium oxide: Na₂O (Two positive, two negative)
  • Magnesium oxide: MgO (Two positive, two negative)
  • Magnesium chloride: MgCl₂ (Two positive, two negative)
• What is the formula for sodium chloride?

  NaCl
• What is the formula for sodium oxide?

  Na₂O
• What is the formula for magnesium oxide?

  MgO
• What is the formula for magnesium chloride?

  MgCl₂