How many elements does this cover?

All 118 confirmed elements, from hydrogen (atomic number 1) through oganesson (118). This includes the synthetic superheavy elements in period 7 that have only been produced in particle accelerators.

Where do the atomic masses come from?

Atomic weights follow the IUPAC 2021 standard atomic weights. For radioactive elements with no stable isotope, the value shown is the mass number of the most stable known isotope rather than a weighted average.

What does the electron configuration shorthand mean?

Configurations use noble-gas core notation. For example, iron is written as [Ar] 3d6 4s2, meaning the argon core plus six 3d and two 4s electrons. This is the standard compact way chemists write configurations.

Why is the group blank for some elements?

Lanthanides and actinides (the f-block) sit outside the numbered groups 1 to 18 in the standard 18-column table, so their group is shown as a dash. Their period is still listed.

Can I search by symbol case-insensitively?

Yes. Searching is case-insensitive, so fe, Fe, and FE all find iron. Two-letter symbols like Na, Cl, and Mg work the same way as single-letter ones.

What is the Periodic Table Element Lookup?

Look up any of the 118 chemical elements by name, symbol, or atomic number. See atomic mass, group, period, category, and full electron configuration with noble-gas core shorthand. Runs in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Periodic Table Element Lookup

Name: Periodic Table Element Lookup
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

The periodic table organises every known chemical element by increasing atomic number into rows (periods) and columns (groups) that reflect recurring chemical behaviour. This lookup lets you find any of the 118 elements instantly by name, symbol, or atomic number and read its core properties.

How it works

The table is sorted by atomic number Z, which is the number of protons in the nucleus and the defining identity of an element. As you type, the list filters on three fields at once: the element name, its chemical symbol, and its atomic number. An element’s position is fixed by two coordinates:

Group (column 1 to 18) groups elements with similar valence-electron structure and therefore similar chemistry.
Period (row 1 to 7) corresponds to the highest occupied principal energy level.

Electron configurations are shown in noble-gas core shorthand: the symbol of the preceding noble gas in brackets stands in for the filled inner shells, followed by the outer sub-shells. Reading [Ne] 3s2 3p4 for sulfur tells you it has a neon core plus six outer electrons.

The block structure of the table

The 118 elements fall into four blocks based on which sub-shell their outermost (valence) electrons occupy:

s-block (groups 1–2): alkali metals and alkaline earth metals. Hydrogen and helium are also here. These elements are highly reactive with one or two valence electrons.
p-block (groups 13–18): includes metals, metalloids, non-metals, and the noble gases. This is where most of chemistry’s diversity lives — carbon (group 14), nitrogen (group 15), oxygen (group 16), halogens (group 17).
d-block (groups 3–12): transition metals such as iron, copper, gold, and platinum. Characterised by partially filled d sub-shells and variable oxidation states.
f-block: lanthanides (cerium to lutetium) and actinides (thorium to lawrencium), pulled below the main table in the conventional layout. They have partially filled f sub-shells and are why some elements show no group number in this reference.

Why electron configuration matters

An element’s electron configuration determines almost everything about its chemical behaviour: what bonds it forms, what oxidation states it adopts, how it reacts with acids, whether it is a conductor. The noble-gas shorthand makes this readable at a glance — elements in the same group share the same valence-electron pattern (just in a higher shell), which is why they behave similarly. Sodium [Ne] 3s1 and potassium [Ar] 4s1 both have one s-electron and both react vigorously with water.

Notes and search tips

Searching 26 jumps straight to iron (Fe); searching the symbol Fe or the name iron both work. Case does not matter — fe, Fe, and FE all find iron. The f-block lanthanides and actinides show a dash for group because, in the conventional 18-column layout, they are pulled out below the main body and do not occupy a numbered group. For radioactive elements such as technetium or the superheavy period-7 elements, the listed mass is the mass number of the most stable isotope, which is why those values are whole numbers rather than weighted averages.