Classifying Elements & Predicting Properties
Periodic table
- Elements are arranged on the Periodic Table in order of increasing atomic number, where each element has one proton more than the element preceding it
- The table is arranged in vertical columns called Groups numbered 1 – 8 and in rows called Periods
- Period: these are the horizontal rows that show the number of shells of electrons an atom has
- Eg 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
- Eg Group 4 elements have atoms with 4 electrons in the outermost shell, Group 6 elements have atoms with 6 electrons in the outermost shell
All elements are arranged in the order of increasing atomic number from left to right
Predicting properties using the Periodic table
- Because there are patterns in the way the elements are arranged on the Periodic table, there are also patterns and trends in the chemical behaviour of the elements
- There are trends in properties down Groups and across a Period
- All of the Group I elements, for example, react very quickly with water
- In this way the Periodic table can be used to predict how a particular element will behave
