Atomic Structure and the Periodic Table

• This topic is absolutely essential for chemistry first part of a QA atomic structure and the periodic table
• The periodic table is a list of all the elements which are known to exist
• Element


  A single type of atom
• Atom


  A very small thing, the word 'atom' is Greek for 'uncuttable'
• The periodic table tells us loads of information about the elements and the range of elements that are known to exist
• Compound


  Two or more elements that are chemically bonded together
• Structure of an atom

  • Electrons on the shells around the outside
  • Protons in the middle
  • Neutrons in the middle
  • The nucleus
• Protons


  In the nucleus, have a mass of 1 and a charge of plus 1
• Neutrons


  In the nucleus, have a mass of 1 and a charge of 0
• Electrons


  On the outer shells, have a mass of 1/1000 and a charge of minus 1
• Information on the periodic table

  • Element name
  • Element symbol
  • Atomic number
  • Mass number
• Atomic number


  The number of protons and electrons in an atom
• Mass number


  The number of protons plus the number of neutrons
• Balancing a chemical equation

  1. Write the reactants and products

  2. Count the number of each element on each side

  3. Adjust the coefficients to balance the equation
• Important chemical formulas to learn

  • Water (H2O)
  • Hydrogen gas (H2)
  • Oxygen gas (O2)
  • Nitrogen gas (N2)
  • Ammonia (NH3)
  • Hydrochloric acid (HCl)
  • Sulfuric acid (H2SO4)
  • Carbon dioxide (CO2)
• Mixture


  Lots of different things, some chemically bonded, some not
• Separation techniques


  • Distillation
  • Evaporation
  • Filtration
  • Fractional distillation
• The plum pudding model of the atom was replaced by the nuclear model proposed by Rutherford
• Rutherford's experiment with alpha particles and gold foil led to the discovery of the atomic nucleus
• Chadwick discovered neutrons, which led to the development of the current model of the atom
• Groups


  Go down the periodic table, indicate the number of electrons in the outer shell
• Periods


  Go across the periodic table, indicate the number of electron shells
• Determining the electronic configuration of an element

  1. Identify the period to get the number of shells

  2. Identify the group to get the number of electrons in the outer shell

  3. Fill the shells with electrons
• Sodium ion


  Sodium loses one electron, resulting in a positive charge of +1
• Metals


  • Lose electrons, form positive ions
  • Nonmetals gain electrons, form negative ions
• Groups on the periodic table

  • Group 1 (alkali metals)
  • Group 2 (alkaline earth metals)
  • Group 7 (halogens)
  • Group 8 (noble gases)
  • Transition metals
• Mendeleev's periodic table had gaps that allowed him to predict the properties of undiscovered elements
• Halogens


  • Exist as diatomic molecules
  • Highly reactive, want to gain one electron
  • Reactivity decreases down the group
• More reactive element


  Can displace a less reactive element from a compound
• Alkali metals


  • Soft, grey metals
  • Highly reactive with water, forming metal hydroxides and hydrogen gas
  • Reactivity increases down the group
• Transition metals


  • Hard, shiny, good conductors
  • Used in jewelry, wires, and coatings