Periodic Table

• Periodic table


  A list that shows all the elements that have been discovered
• How elements are arranged on the periodic table


  They are arranged in order of atomic number
• Approximate number of elements

  • 100/118
• Atoms


  Tiny particles that everything is made of
• Element


  Made of only one type of atom, found on the periodic table e.g. Carbon, Sodium, Phosphorus
• Molecule


  Made up of two or more atoms chemically combined, can be the same or different e.g. H2, O2, H2O (water), CH4 (methane), CO2 (carbon dioxide), NH3 (ammonia)
• Compound


  Made up of two or more different atoms chemically combined e.g. FeS (iron sulphide)
• Mixture


  Contains elements, molecules, compounds that are not chemically combined, can be separated without using chemical methods
• Symbols for the first 20 elements in the periodic table


  • H
  • He
  • Li
  • Be
  • B
  • C
  • N
  • O
  • F
  • Ne
  • Na
  • Mg
  • Al
  • Si
  • P
  • S
  • Cl
  • Ar
  • K
  • Ca
• Extra element symbols


  • Iron - Fe
  • Copper - Cu
  • Nickel - Ni
  • Zinc - Zn
  • Gold - Au
  • Silver - Ag
  • Platinum - Pt
• Location of metals on the periodic table


  On the left hand side (to the left of Al, Ge, Sb, Po)
• Location of non-metals on the periodic table

  On the right hand side
• Group 1 metals


  Alkali metals
• Group 2 metals


  Alkali Earth metals
• Metals between group 2 and 3

  Transition metals
• Group 0 elements (non-metals)

  Noble gases
• Elements that exist as diatomic molecules


  • O2 - Oxygen
  • N2 - Nitrogen
  • H2 - Hydrogen
  • Cl2 - Chlorine (all halogens)
• Using the periodic table to find mass number and atomic number


  Mass number of carbon = 12 and atomic number = 6
• Sub-atomic particles in the nucleus of an atom


  • Protons
  • Neutrons
• Atomic number


  The number of protons an atom contains
• Atomic mass


  The number of protons + neutrons an atom contains
• Location of protons and neutrons in an atom

  In the nucleus
• Location of electrons in an atom

  In shells/energy levels surrounding the nucleus
• Number of electrons in an atom


  The same as the number of protons
• Overall charge of an atom


  Neutral, because it contains the same number of positively charged protons as negatively charged electrons
• What a compound formula tells us

  The ratio of elements in the compound
• Calcium carbonate (limestone) formula CaCO3


  • 1 Ca (calcium) atom
  • 1 C (carbon) atom
  • 3 O (oxygen) atoms
• Number of types of element in calcium carbonate

  • 3
• Number of atoms in calcium carbonate

  • 5
• Ways to separate mixtures


  • Sieving - different sized solids
  • Filtering - liquid and a solid
  • Decanting - liquid and a solid
  • Distillation - two miscible liquids with different boiling points
  • Fractional distillation - a number of miscible liquids with different boiling points
  • Chromatography - mixtures of liquids
  • Evaporation - solid and liquid
  • Crystallisation - solid and liquid
• Atom diagram


  • Nucleus (protons and neutrons)
  • Shells - showing the electrons
• An atom has no overall charge because the number of protons is equal to the number of electrons
• Nuclear symbols of elements


  • Symbol tells name of element
  • Mass number (protons + neutrons)
  • Atomic number (number of protons)
• Calculating number of neutrons


  Mass number - Atomic number
• Calculating relative formula mass for water (H2O)

  1 + 1 + 16 = 18
• Calculating relative formula mass for Potassium Sulphate (K2SO4)


  (39 x 2) + 32 + (16 x 4) = 174
• Why elements combine to form compounds

  To get a full outer shell of electrons (gain noble gas configuration)
• An Iron atom has 26 protons, 26 electrons, and 30 neutrons
• Alkali metals have 1 electron in their outer shell
• Group 0 elements have 8 electrons in their outer shell (except Helium which has 2)