All 118 elements
Atomic number, symbol and weight, with the period, group and electron configuration worked out from them. Even the seat in the table comes from the number.
The periodic table
Rows are periods, columns are groups. Tap any square to open that element.
Nonmetal7
Poor conductors that tend to take on electrons and become negative ions.
Noble gas7
Their outer shell is already full, so they barely react with anything.
Halogen6
One electron short of a full shell, which makes them highly reactive.
Alkali metal6
They give up their single outer electron so readily that water sets them off.
Alkaline earth metal6
Metals that give up two electrons — vigorous, but less so than the alkali metals.
Transition metal40
Metals filling an inner shell as they go, giving several oxidation states and colour.
Post-transition metal11
The metals to the right of the transition block: softer, with lower melting points.
Metalloid7
Part metal, part nonmetal — which is what makes semiconductors possible.
Lanthanide14
The first of the two rows pulled out below the table. So alike that separating them is hard work.
Actinide14
The second row below the table. All radioactive, and most of them made by people.
How to read this
- A row (period) is the number of electron shells. Elements in period 3 carry three of them.
- A column (group) tells you how many electrons sit in the outer shell — which is why a group behaves alike.
- Atomic weight runs at roughly twice the atomic number: about as many neutrons as protons.
- The 28 lanthanides and actinides are drawn below the table. Slotting them in would stretch it to 32 columns.
Frequently asked questions
Q. What is the table ordered by?
Atomic number — the count of protons. Lay the elements out in that order and start a new row where the properties begin to repeat, and similar elements line up in columns. The seats on this page are computed from that number.
Q. What do the rows and columns mean?
A row (period) is the number of electron shells; a column (group) is how many electrons sit in the outermost one. Elements in a group react alike because that outer count is the same.
Q. Why does it stop at 118?
Because 118 is as far as confirmed elements go. Attempts at 119 continue but nothing has been confirmed. From neptunium at 93 onwards, almost everything is made by people.
Q. Why are atomic weights not whole numbers?
An element comes as a mixture of isotopes with different neutron counts, and the weight is the average over natural abundance. Where no isotope is stable, the mass number of the longest-lived one is listed instead.
Q. Where do these values come from?
Only the atomic number, the symbol and the weight are stored. Period, group, block, category and electron configuration are all worked out from the number, so the seat in the table cannot disagree with the text.