Final answer:
The chemical symbol for Oxygen is 'O'. It represents both the element on the periodic table and a single atom of oxygen.
Step-by-step explanation:
The chemical symbol for the element Oxygen is O. This symbol is used to represent both the element on the periodic table and a single atom of oxygen. When oxygen forms a molecule with two oxygen atoms, the molecular formula is denoted as O₂, where the subscript '2' indicates the number of oxygen atoms present in the molecule. This distinction is vital to differentiate between the elemental form and the diatomic molecule.
It's important to note that all chemical symbols contain one or two letters, and if two letters are present, the second one is always in lowercase. Additionally, the first letter is always capitalized to avoid confusion with other notations, such as chemical compounds.