# Lesson 2.1 - The Periodic Table

## Periodic table

The periodic table is used to group all the discovered elements.

As of this document, there are 118 discovered elements, ranging from hydrogen (1) to oganesson (118).

It sorts the elements into groups and columns based on their properties.

## Sorting the elements

The elements in the periodic table are sorted by their **atomic number**.

This is the number of protons it contains.

For instance, carbon (6) is before oxygen (8).

## Groups and periods

We can sort the elements into **groups** and **periods**.

These are based on the **chemical properties** of the element.

In general, metals are on the left, with non-metals on the right.

The groups range from 1-8 (group 8 is called group 0).

The periods range from 1-7.

## Uses of the periodic table

We can use the periodic table to find out properties of an element.

For example, Period 3 elements will always have 3 electron shells (we will learn this in the next lesson).

The periodic table can also be used to predict properties of new elements.

If a new element in Group 0 is discovered, scientists can look at the properties of other Group 0 elements and make predictions based on those.
