How periodic table lookup works
The periodic table organises the 118 known chemical elements by increasing atomic number (the number of protons in the nucleus). Each element has a one- or two-letter symbol (H, He, Li...), a name (Hydrogen, Helium...) and an atomic mass expressed in atomic mass units.
Elements are arranged into periods (horizontal rows 1-7) and groups (vertical columns 1-18). They are also grouped by category — alkali metals, alkaline earth metals, transition metals, post-transition metals, metalloids, nonmetals, halogens, noble gases, lanthanides and actinides — which predicts their chemical behaviour.
Enter a symbol (such as Fe), a name (such as Iron) or an atomic number (such as 26) and the tool finds the matching element and shows its full data. The lookup is case-insensitive and tries the symbol, then the exact name, then the number, then a name prefix, so 'go' finds Gold.