The Modern Periodic Table (Edexcel GCSE Chemistry: Combined Science)

• There are over 100 chemical elements which have been isolated and identified
• Elements are arranged on the periodic table in order of increasing atomic number
  • Each element has one proton more than the element preceding it
  • This is done so that elements end up in columns with other elements which have similar properties

• The table is arranged in vertical columns called groups and in rows called periods
  • Period: These are the horizontal rows that show the number of shells of electrons an atom has and are numbered from 1 - 7
  • E.g. elements in period 2 have two electron shells, elements in period 3 have three electron shells

• Group: These are the vertical columns that show how many outer electrons each atom has and are numbered from 1 – 7, with a final group called group 0 (instead of group 8)
  • E.g. group 4 elements have atoms with 4 electrons in the outermost shell, group 6 elements have atoms with 6 electrons in the outermost shell and so on

The Periodic Table

The Periodic Table of the Elements

• The metals that are further to the left on the periodic table do not have many electrons to remove from their outer shells
• As you descend the groups, the outer shell electrons become further away from the nucleus due to increasing atomic size
  • This weakens their attraction to the nucleus

• The further down the group an element is, the more easily it can react and lose its outer electron(s)
• For the non-metals which are placed on the right-hand side, the opposite is the case
• These elements have a lot of outer electrons, and it is more feasible for them to gain (or share electrons) to obtain a full outer shell
  • This is a key difference between metals and non-metals and influences their chemical behaviour

• It also clearly illustrates the important link between an element’s atomic number and how it reacts as well as its position on the periodic table
• The general properties of most metals and non-metals are summarised below:

A summary of the General Properties of Metals & Non-metals