Periodic table

• Atom


  Central nucleus comprising protons and neutrons, with electrons orbiting the nucleus
• Protons


  Determine which element the atom is
• Hydrogen

  • Smallest element, with 1 proton and 1 electron
• There are around 100 different elements
• Periodic table


  Organizes elements into boxes, with each box representing a different element
• Nuclear symbol


  The one or two letter symbol that represents the element name
• Atomic number


  The number of protons in the atoms of that element, unique to each element
• Isotopes


  Different forms of the same element that have the same number of protons but a different number of neutrons
• Relative atomic mass

  The average mass of all the isotopes that make up a particular element
• Calculating relative atomic mass


  Multiply each isotope's abundance by its mass, sum these, then divide by the sum of the abundances of all the isotopes
• Elements are arranged by increasing atomic number.
• Groups contain elements with similar properties, while periods contain elements that have the same number of energy levels.
• The periodic table is organised into groups (columns) and periods (rows).
• Groups (columns) contain elements with similar chemical properties.
• Periods (rows) contain elements with similar electron configurations.
• Metals tend to be found on the left hand side of the periodic table, while nonmetals are located towards the right hand side.
• Periods increase from top to bottom, indicating an increase in the number of electron shells.
• Group 2 contains metals called alkaline earth metals.
• Group 7 contains non-metal gases called halogens.
• Periods (rows) contain elements with the same number of electron shells.