An element is a substance that contains only one kind of atom. Each element is made up of atoms with the same number of protons in their nuclei. The number of protons in an atom's nucleus determines the element to which it belongs.

For example, all atoms with one proton in their nuclei are hydrogen atoms. All atoms with six protons in their nuclei are carbon atoms. And so on.

There are 118 known elements. Each element has its own unique symbol, which is used to represent it on the periodic table of elements.

The periodic table is a chart that organizes the elements according to their atomic number, electron configuration, and recurring chemical properties.