If the chemical symbol consists of more than one letter, any subsequent letters are lowercase. Example: Hydrogen → H, Helium → He; 118 Elements and Their Symbols and Atomic Numbers.

Element Symbols: Each element is represented by a unique one- or two-letter symbol, usually derived from its English or Latin name (e.g., H for Hydrogen, Au for Gold from "Aurum").

The symbol for the element is the first letter of its English or Latin name, written as a capital letter. If several elements have the same first letter, a second, lower case letter is added.