TOPIC 1

• Atom


  Tiny particles of matter that are the building blocks of all matter
• Subatomic particles


  • Protons
  • Neutrons
  • Electrons
• Nucleus


  The centre of the atom where the protons and neutrons are located
• Shells


  Orbital paths where the electrons move very fast around the nucleus
• The mass of the electron is negligible, hence the mass of an atom is contained within the nucleus where the protons and neutrons are located
• Element


  A substance made of atoms that all contain the same number of protons and cannot be split into anything simpler
• There is a limited number of elements, and all elements are found on the Periodic Table
• Chemical symbol


  A unique symbol representing each element, e.g. N stands for nitrogen
• Where a symbol contains two letters, the first one is always written in uppercase letters and the other in lowercase e.g., sodium is Na, not NA
• Elements that must be written as molecules

  • H2
  • N2
  • O2
  • F2
  • Cl2
  • Br2
  • I2
• Atomic number

  The number of protons in the nucleus of an atom
• Mass number


  The total number of protons and neutrons in the nucleus of an atom
• You will be provided with a Periodic Table in your Chemistry exams
• You need to be able to use the names and symbols for the first 20 elements in the table
• You also need to be able to use the name and symbols of the elements in group 1, group 7 and any other elements specified in these notes
• Compound


  A pure substance made up of two or more elements chemically combined and which cannot be separated by physical means
• The properties of compounds are usually quite different from the elements that form them
• There is an unlimited number of compounds, and the chemical formula is what tells you the ratio of atoms in a compound
• Ionic compound

  Contains metal and non-metal elements joined together as particles called ions
• Covalent compound

  Contains only non-metals
• Prefix


  (in covalent compounds) used to show how many of each element is present in the formula (mono, di, tri, tetra, penta)
• Common names of covalent compounds

  • H2SO4 is sulfuric acid
  • NH3 is ammonia
  • CH4 is methane
  • HCl is hydrochloric acid (or hydrogen chloride if it is a gas)
  • C6H12O6 is glucose
  • C2H5OH is ethanol
  • HNO3 is nitric acid
• Word equation


  Shows the reactants and products of a chemical reaction using their full chemical names
• Symbol equation

  Uses the formulae of the reactants and products to show what happens in a chemical reaction
• A symbol equation must be balanced to give the correct ratio of reactants and products
• Law of Conservation of Mass

  The total mass of reactants is always equal to the total mass of products
• Balancing equations

  1. Write the formulae of the reactants and products

  2. Count the numbers of atoms in each reactant and product

  3. Balance the atoms one at a time until all the atoms are balanced

  4. Use appropriate state symbols in the equation
• Half equation

  Shows what happens to the electrons in reactions where atoms, molecules or ions are gaining or losing electrons
• Ionic equation


  Indicates what happens to ions during reactions
• Spectator ions


  Ions which are present but do not take part in reactions
• Mixture


  Contains elements and/or compounds where each constituent retains its chemical properties and can be separated by physical means
• Filtration


  1. Used to separate an undissolved solid from a mixture of the solid and a liquid/solution

  2. A piece of filter paper is placed in a filter funnel above a beaker

  3. A mixture of insoluble solid and liquid is poured into the filter funnel

  4. The filter paper will only allow small liquid particles to pass through as filtrate

  5. Solid particles are too large to pass through the filter paper so will stay behind as a residue