Periodic Table of Elements

What is the periodic table?#

The periodic table arranges all 118 known chemical elements so that elements with similar behaviour land in the same column. The pattern is not decorative — it falls directly out of how electrons fill their shells. Read a row left to right and atomic number climbs one by one; read a column top to bottom and the outermost electrons sit in the same kind of orbital, which is why the column shares chemistry. That single arrangement predicts an enormous amount: reactivity, bonding, the compounds an element forms, even whether it is a metal.

Each cell here carries the data a working reference needs: atomic number, symbol, IUPAC English name, standard atomic weight, the IUPAC category that drives its colour, group and period, the ground-state electron configuration, the discovery year, and a one-line summary of principal uses. The roughly 34 most recognizable element names are shown in your language; the rest fall back to English, but the symbol and atomic number beside them are universal.

How to use it#

1. Type in the Search box to filter. It matches the localized name, the English name, the symbol (Fe), the atomic number (26), or the category (halogen). Searching 26, Fe, or iron all isolate the same cell.
2. The colour Legend below the search box doubles as a filter — click a category (say noble-gas) to dim everything else, click it again or click all to restore the full table.
3. Click any cell to open the detail panel: symbol with the atomic number in the corner, full name, category, atomic weight, electron configuration, group, period, discovery year, and a short uses line.
4. Use the copy button on any detail value to grab it — handy for pasting a configuration like [Ar] 3d6 4s2 into notes.
5. The two separated rows at the bottom are the lanthanides (La–Lu, Z 57–71) and actinides (Ac–Lr, Z 89–103); they belong in the f-block and are shown detached only so the main table stays a readable rectangle.

Key features#

• All 118 elements, from hydrogen (Z=1) to oganesson (Z=118), each with weight, category, electron configuration, discovery year and a uses blurb.
• Search + category filter together. Combine a text query with a category toggle to narrow fast — transition-metal plus nothing shows every metal in the d-block at a glance.
• Colour-coded by IUPAC category, with a matching dark-mode palette so the table stays readable at night.
• Localized names for common elements via a small per-locale table; the symbol and atomic number are always shown alongside, so an English-only name never confuses the reader.
• Click-to-copy details. No retyping of long electron configurations.

Worked example#

A chemistry student needs iron’s electron configuration for a worksheet. Type Fe (or 26, or iron) in the search box — only one cell stays lit. Click it. The detail panel shows:

Fe   26
Iron
Transition metal
Atomic mass:   55.845
Configuration: [Ar] 3d6 4s2
Group: 8    Period: 4
Discovered: Ancient
Uses: Backbone of steel; tools, vehicles, reinforcement, magnets.

Reading that, two things click at once. Iron sits in group 8, period 4 — the first row of the d-block where the 3d sub-shell is filling, which is exactly what [Ar] 3d6 4s2 says (six electrons in 3d, two in 4s). And because it shares its group with ruthenium and osmium below it, the student can predict those two will also have two unpaired 3d/4d/5d electrons and similar chemistry. That is the whole point of the table: one cell explains its column.

FAQ#

Why is hydrogen placed above the alkali metals when it is a nonmetal?#

Hydrogen has a single electron in an s-orbital, so structurally it belongs in group 1 — but it is a gas, not a metal, and its chemistry is closer to the halogens (it can gain one electron to fill its shell). Most tables keep it in group 1 by orbital shape and footnote the exception; some two-table layouts move it to the halogens. Either way the cell itself is just labelled nonmetal here.

What does an atomic weight in square brackets mean, like [98]?#

Brackets mark an element with no stable isotope — usually synthetic or heavily radioactive. The number inside is the mass number of the longest-lived isotope we know, not a true average weight (which cannot be measured because the element does not stick around). Technetium [98] and all the transuranium elements carry this notation.

What is the difference between a group and a period?#

A group is a column and numbers the valence-electron family (groups 1–18); elements in a group share outer-shell structure and therefore chemistry. A period is a row and numbers how many electron shells are occupied (periods 1–7). Sodium is group 1, period 3: one valence electron, three shells total.

Why are the lanthanides and actinides pulled out to the bottom?#

They would each insert into the main body around columns 3, pushing the table to 32 wide and making it unreadable on a screen. The convention is to display them as two detached rows (the f-block) while the grid still records their true group as 0 so the data stays correct.