Periodic table and atomic structure

• Elements within the same group have similar chemical properties.
• The periodic table is organised into groups (columns) and periods (rows).
• An element is a substance that cannot be broken down into simpler substances by chemical means as it consists of only one type of atom
• Protons are positively charged and found in the nucleus of an atom
• Atoms are very small particles which make up all matter, they consist of protons, neutrons and electrons
• Neutrons are neutral particles found in the nucleus of an atom
• Electrons are negatively charged and orbit around the nucleus of an atom
• Atoms can gain or lose electrons to form ions, which can then bond with other atoms to make molecules
• The periodic table shows how elements are arranged based on their properties such as reactivity and electron configuration
• Group 1 are the alkali metals and they are soft and have low melting points
• Group 7 are the halogens and they are reactive non-metals that easily form compounds with other elements
• Group 2 are alkaline earth metals, they have a high melting point and are soft and malleable
• Group 8/0 are noble gases, they are inert and non-flammable
• Mendeleev arranges the elements in order of increasing atomic weight. Groups of similar properties. He left gaps for elements that were not known. Predicted properties of undiscovered elements.
• Group 1 metals are very reactive therefore stored in oil to protect them from reactions with air or water
• When handling Group1 with water :wear gloves and use a safety screen and glass. Use a rice grain sized amount of the chemical.Then fill the water trough.
• Metal + water* metal hydroxide + hydrogen
• Atoms have no charge as the number of positive protons equals the number of negative electrons
• Ions are atoms which have lost or gained one or more electrons so they now have an overall charge
• The group number tells us how many valence electrons there are in the outer shell of the element
• Atomic number is the number of protons in an atom of an element.(equals number of electrons)
• Mass number is the total number of protons and neutrons in an atom's nucleus.
• The first shell of an atom contains 2 electrons
• Remaining shells hold up to 8 electrons
• The period tells you the number of shells of elements in the row
• Group 1 - The Alkali Metals


  • Lithium (Li)
  • Sodium (Na)
  • Potassium (K)
• Alkali Metals


  • Very reactive
  • Must be stored under oil to prevent reaction with air and water
• Reaction with water

  1. Floats on the surface of the water

  2. Hissing sound

  3. Eventually disappears
• Lithium reaction with water

  • Floats on the surface of the water
  • Hissing sound
  • Eventually disappears
• Sodium reaction with water

  • Floats on the surface of the water
  • Hissing sound
  • Eventually disappears
  • Burns with a yellow/orange flame
  • Turns into a ball
• Potassium reaction with water

  • Floats on the surface of the water
  • Hissing sound
  • Eventually disappears
  • Burns with a lilac flame
  • Turns into a ball
• Mass number


  Number of protons and neutrons in the nucleus of an atom
• Atomic number


  Number of protons and electrons in an atom (protons = electrons)
• Ions


  Charged particles formed when atoms have gained or lost electrons
• Nucleus

  Area in an atom containing neutrons and protons (centre)
• Molecular ion

  Charged particles containing more than one atom
• Ionic bond

  The electrostatic force of attraction holding oppositely charged ions together
• Mole

  6x10^23 particles
• Sub-atomic particles

  • Electron
  • Proton
  • Neutron
• Electrons have a mass of 1/2000 and a charge of -1