ElementsHow to read the table
Each tile is one element. Elements run from left to right in order of atomic number, the number of protons in one atom. The seven rows are called periods and the eighteen columns are called groups. Elements in the same group have the same number of outer electrons, so they react in similar ways: every metal in the first column reacts with water, and every gas in the last column reacts with almost nothing.
The colours show ten families, such as alkali metals, halogens and noble gases. Metals fill the left and centre. Nonmetals sit at the upper right. A stair-step line of metalloids runs between them. Read the full guide.
What you can do here
- Sort all elements by mass, melting point, density or year of discovery.
- See the record holders: densest, lightest, highest melting point and more.
- Work out the molar mass of any formula, such as H2SO4 or Ca(OH)2.
- Practise symbols with the quiz.
- Learn about trends, electron shells and symbols that come from Latin.
Questions
How many elements are there?
There are 118 known elements, numbered 1 (hydrogen) to 118 (oganesson). About 94 occur in nature. The rest have been made in reactors or particle accelerators.
Why does the table have this shape?
Elements are placed in order of atomic number, and a new row starts each time a new electron shell begins to fill. This puts elements with the same number of outer electrons in the same column, and they behave alike.
Why are two rows drawn below the table?
The lanthanides (57 to 71) and actinides (89 to 103) belong inside rows 6 and 7. They are drawn below only so the table is not too wide for a page.
What do the numbers on each tile mean?
The small number is the atomic number: the count of protons in the atom. The letters are the symbol. Open any tile to see the atomic mass and all other facts.
Can I print the table?
Yes. Use the print command of your browser on this page and choose landscape. The search box and buttons are left out of the print.