Periodic Table Explorer
Press any element for its details, search by name, symbol or atomic number, or dim everything except one category such as the noble gases.
Relative atomic masses are the standard values, shortened. A value in brackets in the data is the mass number of the longest-lived isotope, because the element has no stable form. Elements 109 to 118 are marked as having unknown properties because so few atoms have been made. States are at about 20 degrees Celsius. Electron arrangements are shown for the first 20 elements, as at GCSE.
Worked examples
Sodium
Na, atomic number 11
Group 1, period 3, alkali metal, electron arrangement 2, 8, 1
Relative atomic mass 22.990.
Iron
Fe, atomic number 26
Group 8, period 4, transition metal, solid, mass 55.845
The electron arrangement is not shown beyond the first 20 elements.
About Periodic Table Explorer
The periodic table lays out the chemical elements in order of atomic number, which is the number of protons in each atom. Rows are called periods and columns are called groups, and the elements in a group behave alike: the alkali metals in group 1 are soft and react strongly with water, while the noble gases in group 18 hardly react at all. This explorer shows all 118 elements, coloured by category, with the lanthanides and actinides in their own rows below the main table.
Press an element to see its atomic number, symbol, name, relative atomic mass, group, period, category and state at room temperature. For the first 20 elements, the ones used at GCSE, it also shows the electron arrangement, such as 2, 8, 1 for sodium. Type a name, a symbol or an atomic number to find an element, or choose a category to fade everything else. The names use British spelling, such as aluminium and caesium, and the masses are the standard atomic weights, shortened as in most textbooks. A mass in brackets is the mass number of the longest-lived form of an element that has no stable form.
How to use Periodic Table Explorer
- Press any element in the table, or type a name, symbol or number in the search box.
- Read the details under the table.
- Choose a category to fade the rest and see where a family sits.
- Compare elements in the same group, which share similar properties.
Common uses
- GCSE chemistry revision
- Finding an atomic number or mass quickly
- Seeing where metals, non-metals and metalloids sit
- Learning the names of the groups
Frequently asked questions
What is the atomic number?
It is the number of protons in the nucleus of an atom, and it identifies the element. In a neutral atom it is also the number of electrons. Iron has atomic number 26.
What is relative atomic mass?
It is the average mass of the atoms of an element compared with one twelfth of a carbon-12 atom, taking account of the mix of isotopes. Chlorine is 35.45 because it is a mixture of chlorine-35 and chlorine-37.
Why are some masses in brackets?
Elements with no stable isotope have no standard value. The number in brackets is the mass number of the longest-lived isotope known, such as 98 for technetium. For the very heaviest elements the value depends on the source.
How is the electron arrangement worked out?
Electrons fill shells in order: 2 in the first, up to 8 in the second, up to 8 in the third until calcium. So sodium (11 electrons) is 2, 8, 1.
Why are elements 109 to 118 grey?
So few atoms of them have ever been made that their chemical properties are not known, so they are marked as unknown properties.