Periodic Table of the Elements — Interactive, with Names

The periodic table is a chart that arranges all known chemical elements by atomic number, electron configuration and recurring chemical properties. Elements with similar behaviour fall in the same column, so the layout helps predict how an element will react and what its properties are.

There are 118 confirmed elements in the periodic table. Elements 1 to 94 occur naturally on Earth, at least in traces; elements 95 to 118 have only been made in laboratories and reactors. The most recent additions — nihonium, moscovium, tennessine and oganesson — were named in 2016.

A period is a horizontal row of the periodic table. Every element in a period has the same number of occupied electron shells, and the period number equals that number of shells. Moving left to right across a period, atomic number increases and properties change gradually from metallic to non-metallic.

The vertical columns are called groups (or families). Elements in a group have the same number of outer electrons and therefore similar chemistry, like the reactive alkali metals in group 1 or the unreactive noble gases in group 18.

There are 7 periods. Period 1 holds only hydrogen and helium, periods 2 and 3 have 8 elements each, periods 4 and 5 have 18, and periods 6 and 7 have 32 when the lanthanides and actinides are included.

Elements are arranged left to right and top to bottom by increasing atomic number, the number of protons in the nucleus. Rows are periods and columns are groups, so elements with similar outer electron arrangements line up in the same column. The table is also divided into s, p, d and f blocks, and into categories such as metals, nonmetals and metalloids. The lanthanides and actinides are shown in two rows below the main table.

Element 67 is holmium (symbol Ho), a soft, silvery-white lanthanide metal in period 6 with an atomic mass of about 164.93. It was discovered in 1878 and named after Stockholm, the Latin Holmia. See the holmium page for its full properties.

Each tile shows an element’s atomic number (the number of protons), its chemical symbol, its name and usually its atomic mass. Read across a row to follow a period and down a column to follow a group. Tile colour shows the element’s category, and the position tells you its electron shells and block. Click any element here for its full properties.

There are 18 groups, numbered 1 to 18 from left to right. Group 1 holds the alkali metals (plus hydrogen), group 17 the halogens and group 18 the noble gases. The lanthanides and actinides sit between groups 2 and 3 and are usually not assigned a group number.

The periodic table was created by Dmitri Mendeleev, who published the first widely recognised version in 1869. He arranged elements by atomic weight and chemical behaviour and left gaps for undiscovered elements, correctly predicting the properties of gallium, scandium and germanium. Today the table is ordered by atomic number, following Henry Moseley’s work in 1913.

Dmitri Mendeleev, a chemistry professor in St Petersburg. His 1869 table is called the first successful periodic table of the elements because it left spaces for elements nobody had found yet and predicted their properties, and the predictions were later confirmed.

Mendeleev arranged the 63 elements known in 1869 in order of increasing atomic weight and started a new row whenever the chemical properties began to repeat, so that similar elements fell into the same group. Where the weights and the chemistry disagreed he followed the chemistry, placing tellurium before iodine even though tellurium is heavier.

Mendeleev left gaps because he believed some elements had not been discovered yet. Instead of forcing a known element into a group where it did not fit, he left the space empty and predicted the missing element’s properties from its neighbours. Gallium (1875), scandium (1879) and germanium (1886) were later discovered and matched his predictions closely.

In the modern periodic table, elements are arranged in order of increasing atomic number, the number of protons in the nucleus, not atomic weight as in Mendeleev’s table. They sit in 7 periods (rows) and 18 groups (columns), and elements in the same group have the same number of outer-shell electrons, which gives them similar chemical properties.

The alkali metals are in group 1, the first column on the left of the periodic table. They are lithium, sodium, potassium, rubidium, caesium and francium. Hydrogen sits at the top of group 1 too, but it is a nonmetal and not an alkali metal.

Na is the symbol for sodium, element 11. It is an alkali metal in group 1, period 3, with an atomic mass of about 22.99. The symbol comes from natrium, the element’s Latin name.

Cu is the symbol for copper, element 29. It is a transition metal in group 11, period 4, with an atomic mass of about 63.55. The symbol comes from cuprum, the Latin name for the metal.

Gold is element 79, with the symbol Au from the Latin aurum. It is a transition metal in group 11, period 6, directly below silver and copper, and has an atomic mass of about 196.97.

In the exam you are given the periodic table printed by your exam board, such as AQA, OCR or Cambridge. They contain the same elements in the same order, but the masses are rounded and the atomic number can be above or below the symbol. For revision, any full periodic table of elements with names, symbols and atomic masses works, including the one on this page.

Yes. The PDF button above the table downloads it, and the printable periodic table page has free PDFs in colour and black and white. They are vector files, so you get an HD periodic table that stays sharp at any zoom level or print size.

The horizontal rows are called periods. There are 7 of them, numbered from the top, and the period number tells you how many electron shells the atoms of those elements have.

Yes. Every element on this periodic table shows its atomic mass, which in grams per mole is the element’s molar mass — for example about 12.011 g/mol for carbon and 15.999 g/mol for oxygen. Open any element page to see it, or use the molar mass calculator to add up the mass of a whole formula such as H2O or CuSO4·5H2O.

Yes. The table at the top of this page shows all 118 elements with their names and symbols, such as H for hydrogen, Fe for iron and Au for gold. You can also browse the full list of elements with names, symbols and atomic numbers, or test yourself with the element quiz.