In chemistry, an element is a pure substance that consists of only one type of atom. Elements are the basic building blocks of all matter in the universe. There are 118 known elements, which are organized on the periodic table according to their atomic number (the number of protons in their nucleus). The first 94 elements occur naturally, while the others have been artificially produced in laboratories.
Atoms are the smallest particles of an element that retain the chemical properties of that element. All atoms of a given element have the same number of protons in their nucleus. The number of protons in an atom's nucleus determines which element it is. For example, all atoms with 6 protons in their nucleus are carbon atoms; all atoms with 26 protons are iron atoms.
The relationship between elements and atoms can be summarized as follows: Elements are made up of atoms; all atoms of a given element have the same number of protons in their nucleus; and the number of protons in an atom's nucleus determines which element it is.