The main groups are numbered from 1 to 7 going from left to right, and the last group on the right is group 0. The section in the middle of the table is called the Transition Metals. You may also see all the groups numbered (including the transition metals), this time from 1 to 18. If you know what one of the elements in a group is like, you can make predictions about the other elements in a group. For example, all the elements in group 1 are reactive metals, and all the elements in group 0 are unreactive non-metals.

The zig-zag line in this diagram separates the metals, on the left, from non-metals, on the right. Hydrogen is a non-metal but it is often put in the middle.

Notice that most elements are metals, rather than non-metals.

Each element has its own chemical symbol, made from letters. Remember that you will only find elements in the periodic table and never compounds. So you won’t find substances like water or copper sulfate in the periodic table.

The modern periodic table

In the modern periodic table:

• elements are arranged in rows, called periods, in order of increasing atomic number

• elements with similar properties are placed in vertical columns, called groups

The table is called the periodic table because elements with similar properties occur at regular intervals.

There are more than 100 different elements. The periodic table is a chart showing all the elements arranged in order of increasing atomic number. The vertical columns in the periodic table are called groups. Each group contains elements that have similar properties.