Aims of this Episode:

  • Describe the structure of the Periodic Table,
  • Identify properties of elements based on their location in the Periodic Table.

Groups of Elements

The main way in which the Periodic Table is organised is in vertical Groups. Elements in the same Group have similar properties. These similarities come from the fact that elements in the same Group have the same number of electrons in their outer shell. (Click here if you need to know more about electron shells.)

Helpfully, the Group number is the number of electrons in the outer most shell. (Lithium is in Group 1, so it has one electron in its outer shell.)

The Groups of the Periodic Table.

One thing that doesn’t fit this pattern of Groups are the Transition Metals. They don’t have a specific group, so don’t fall into the trap of thinking that these have the same number of electrons in their outer shell.

Periods of Elements

If you look across the Periodic Table, there are also similarities between the elements. This time, the elements in each Period will have the same number of electron shells.

Once again, the Period number is the number of shells. For example, Lithium is in Period 2, so we know it has two shells in total.

The Periods of the Periodic Table.

Metals and Non-metals

Finally, the elements can be classed as Metals or Non-metals.

Metals and Non-metals.

What does the Periodic Table tell us?

With very little knowledge of the individual elements, you can steal a lot of information from the Periodic Table. Let’s take our example of Lithium:

  • From its Group, we know it has only one electron in its outer shell;
  • From its Period, we know it has two electron shells;
  • Being on the left of the dividing line, we know its a metal.

Taking the information above one step further we can draw the electron shell diagram extremely quickly – it has two shells and the second shell will only have one electron. The only other fact we need to remember is that the first shell can only have two electrons in it:

Electron Shell Diagram of Lithium.
S@S 021: Periodic Table
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