quantative

• Law of conservation of mass


  No atoms are lost or made during a chemical reaction, so the mass of the products equals the mass of the reactants
• Chemical reaction


  1. Reactants

  2. Products
• In a chemical reaction, the starting materials are called the reactants, and the chemicals that are formed are called the products
• Reactants


  The starting materials in a chemical reaction
• Products


  The chemicals that are formed in a chemical reaction
• Mass of reactants


  Equals mass of products
• The mass of the products must be 95 grams (24 grams of magnesium + 71 grams of chlorine)
• The total mass of the reactants is 124 grams (92 grams of sodium + 32 grams of oxygen), so the mass of the products must also be 124 grams
• The total mass of the products is 200 grams, so the mass of the calcium carbonate that reacted must also be 200 grams
• The total mass of the products is 113 grams, so the mass of the magnesium oxide that reacted must be 113 grams - 73 grams = 40 grams
• Non-metal ions


  Mostly negative
• Charge on metal ions

  Often the same as the group number in the periodic table
• Metal ions


  • Na+
  • Mg2+
  • Al3+
• Metal ions


  • Charge is often the same as the group number in the periodic table
• Transition metals can form several different ions
• Transition metal ions


  • Fe2+
  • Fe3+
  • Cu1+
  • Cu2+
• Non-metal ions


  • O2-
  • F-
• Non-metal ions


  • Charge is often related to the group number in the periodic table
• Some non-metal ions consist of several non-metal atoms chemically combined
• Hydrogen ion (H+) and ammonium ion (NH4+) are positive non-metal ions
• Ionic compound


  The charges on the ions have to cancel out to leave an overall charge of zero
• Ionic compounds


  • Have no overall charge
• Determining the formula of an ionic compound

  1. Identify the charges on the ions

  2. Determine how many of each ion are needed to cancel out the charges

  3. Write the formula using the appropriate number of each ion
• The formulas shown are the most difficult you will see in an exam
• A chemical formula shows the formula of a compound, with capital letters representing elements and small numbers representing the number of atoms of each element
• You are never allowed to change the small numbers in a chemical formula as this produces a different molecule
• Large numbers in front of a chemical formula indicate multiple molecules of that compound
• Balancing a chemical equation

  1. Count the number of atoms of each element on the left and right sides

  2. Ensure the number of atoms of each element is the same on both sides

  3. Use large numbers in front of compounds to balance the equation
• Balancing the unbalanced equation

  1. Add a large 2 in front of Sodium Iodide to balance the Iodine atoms

  2. Add a large 2 in front of Sodium to balance the Sodium atoms
• Balancing the unbalanced equation

  Add a large 2 in front of Hydrochloric Acid to balance the Hydrogen and Chlorine atoms
• Balancing the unbalanced equation

  Add a large 3 in front of Carbon Monoxide to balance the Carbon and Oxygen atoms
• A chemical formula shows the formula of a compound, with capital letters representing elements and small numbers representing the number of atoms of each element
• You are never allowed to change the small numbers in a chemical formula as this produces a different molecule
• Large numbers in front of a chemical formula indicate multiple molecules of that compound
• Balancing a chemical equation

  1. Count the number of atoms of each element on the left and right sides

  2. Ensure the number of atoms of each element is the same on both sides

  3. Use large numbers in front of compounds to balance the equation
• Balancing the unbalanced equation

  1. Count the atoms on each side

  2. Add a large number in front of the compound on the right side to balance the iodine atoms

  3. Add a large number in front of the compound on the left side to balance the sodium atoms
• Relative formula mass


  The sum of the relative atomic masses of the atoms in the numbers shown in the formula
• Relative formula mass has no units
• Relative formula mass never involves big numbers
• Relative formula mass


  • Calculated by multiplying the relative atomic mass of each element by the number of atoms of that element in the formula, then adding all the results together