These are the chemical elements - substances made of a single atom.
Each chemical is unique, composed of a set number of protons, neutrons and electrons, and is identified by a name and a chemical symbol, such as "C" for carbon.
The elements that scientists have discovered (https://t.me/askmenow/2693) so far are listed in the periodic table of elements, and include both elements that are found in nature like carbon, hydrogen and oxygen, as well as those that are manmade, like Lawrencium.
Chemical elements can bond together to form chemical compounds, which are substances made up of multiple elements, like carbon dioxide (CO2 - one carbon atom connected to two oxygen atoms), or multiple atoms of a single element, like oxygen gas (O2 - two oxygen atoms connected together). These chemical compounds can then bond with other compounds or elements to form countless other substances and materials.