C3

• What is the procedure to write the formulae of simple ionic compounds?

  Balance the charges of the ions involved.
• How do you write the formula for simple covalent compounds?

  Imagine what the ion would be and balance the charges.
• What is the formula for water based on its ionic components?

  H₂O, which balances as 2H⁺ and O^2-.
• What principle is used to write balanced chemical equations?

  The principle of conservation of mass.
• How do you write a balanced chemical equation?

  Count the number of atoms of each element on both sides of the equation.
• What is an example of using large numbers to balance an equation?

  Using 3H₂O to balance the equation.
• What is the purpose of using a periodic table in writing formulae?

  To use the names and symbols of common elements.
• What are ions of elements?

  Atoms that have lost or gained one or more electrons.
• Why do atoms form ions?

  To achieve a stable arrangement of electrons similar to a noble gas.
• What charge do group 1 ions have?

  1+ charge.
• What charge do group 6 ions have?

  1. charge.
• How does HCl exist as a compound?

  It forms from an H⁺ ion and a Cl^- ion.
• Why does H₂SO₄ exist as a compound?

  It forms from 2H⁺ ions and a SO₄^2- ion.
• What are the common ions formed by different groups in the periodic table?

  • Group 1: 1+ ions
  • Group 2: 2+ ions
  • Group 3: 3+ ions
  • Group 5: 3- ions
  • Group 6: 2- ions
  • Group 7: 1- ions
• What is the formula for the nitrate ion from nitric acid?

  NO₃^-.
• What is the formula for the chloride ion from hydrochloric acid?

  Cl^-.
• What is the formula for the sulfate ion from sulfuric acid?

  SO₄^2-.
• What is the first step in constructing balanced ionic equations?

  Write out the full chemical equation.
• What do you do with (aq) substances in ionic equations?

  Split them up into ions.
• What are spectator ions in ionic equations?

  Unchanged ions on either side of the chemical equation.
• What do state symbols represent in chemical equations?

  The physical states of products and reactants.
• What does (s) represent in state symbols?

  Solid.
• What does (l) represent in state symbols?

  Liquid.
• What does (g) represent in state symbols?

  Gas.
• What does (aq) represent in state symbols?

  Aqueous.
• What is the definition of the mole?

  The amount of substance measured in moles.
• What is the Avogadro constant?

  1. 02 x 10²³ per mole.
• How is the mass of one mole of a substance related to its relative formula mass?

  It is numerically equal to its relative formula mass in grams.
• What is the mass of one mole of iron if its Ar is 56?

  56 g.
• What is the mass of one mole of nitrogen gas (N₂) if its Mr is 28?

  28 g.
• How can you convert between moles and grams?

  By using the triangle: Moles = Mass / Mr.
• How many moles are there in 42 g of carbon if its Mr is 12?

  1. 5 moles.
• What is the law of conservation of mass?

  No atoms are lost or made during a chemical reaction.
• How can chemical reactions be represented?

  By symbol equations that are balanced in terms of the numbers of atoms.
• How can you use the law of conservation of mass to write chemical equations?

  By ensuring the mass of the products equals the mass of the reactants.
• What are the steps to construct balanced ionic equations?

  1. Write out the full chemical equation.
  2. Split (aq) substances into ions.
  3. Cancel out spectator ions.
  4. Write the remaining ionic equation.
• What is the mass of one mole of a substance?

  28 g
• How many particles are in one mole of a substance?

  It contains the same number of particles as one mole of any other substance.
• How can you convert between moles and grams?

  • Use the formula: Moles = Mass / Molar Mass
  • Rearrange to find Mass: Mass = Moles x Molar Mass
• How many moles are there in 42 g of carbon?

  1. 5 moles