Atoms and elements are related in that elements consist of one specific kind of atom. This means that the atom is the base unit of an element. Atoms consists of a nucleus, which contains protons, neutrons and electrons that orbit around the nucleus.
Hydrogen is an element composed of atoms that have one proton and one electron. However, different isotopes of hydrogen have varying numbers of neutrons.
Different elements have different numbers of protons, which determines an element's atomic number. On the periodic table, the atomic number identifies the specific element and how many protons are in its nucleus. For example, carbon has six protons, so its atomic number is 6.
When two or more elements react chemically, they form a substance called a compound. Some examples of compounds are calcium carbonate (CaCO3) and sodium chloride (NaCl).