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Periodic Table

An interactive periodic table with element details.

1H1.008

Hydrogen

Reactive nonmetal

Atomic mass
Group · Period
Block
State at 20 °C
Electronegativity
Electron configuration

Masses are IUPAC standard atomic weights. A number in [brackets] is the mass number of the most stable isotope. Electronegativity is on the Pauling scale.

When to use it

Use this interactive periodic table to look up any of the 118 elements quickly. It shows the atomic number, symbol, name, atomic mass, group and period, block, state at room temperature, electronegativity and electron configuration. It is handy for chemistry homework, revision and quick checks during lab work.

How to use it

  1. Tap any element in the table to see its details at the top.
  2. Or type in Find an element. You can search by name, symbol or atomic number, such as iron, Fe or 26.
  3. Read the details: Atomic mass, Group · Period, Block, State at 20 °C, Electronegativity and Electron configuration.
  4. Tap a category in the key, such as Halogen or Noble gas, to highlight that group. Tap it again to clear.

Worked example

Search for iron. The table highlights element 26, Fe. Its details show an atomic mass of 55.845 u, group 8 and period 4, the d-block, solid at 20 °C, electronegativity 1.83 and the electron configuration [Ar] 3d6 4s2. The [Ar] part is shorthand for the 18 electrons of argon, the noble gas before it.

For a chemistry question about table salt, look up sodium (22.990, electronegativity 0.93) and chlorine (35.45, electronegativity 3.16). The large difference in electronegativity, 2.23, is why sodium chloride forms an ionic bond.

Reading the table

  • Rows are periods. Moving right, atoms gain one proton and one electron each step.
  • Columns are groups. Elements in the same group have similar outer electrons and often behave alike.
  • Blocks (s, p, d and f) show which type of orbital the outer electrons fill.
  • The two rows at the bottom are the lanthanides and actinides, placed separately to keep the table a sensible width.

Tips

  • Use the categories to revise. Highlight the halogens or alkali metals and learn their trends together.
  • Round masses for school work. Most problems use masses to one decimal place, such as 35.5 for chlorine.
  • Search by number when you are not sure of spelling. Typing 74 finds tungsten, whose symbol W comes from its old name, wolfram.
  • Compare electronegativity to predict bonds. A big difference usually means an ionic bond, a small one a covalent bond.

Common mistakes

  • Mixing up atomic number and mass. The atomic number is the count of protons. The mass includes neutrons too.
  • Assuming symbols match English names. Fe is iron, Na is sodium and K is potassium, from their Latin names.
  • Forgetting the f-block. Lanthanides and actinides belong inside periods 6 and 7.

Frequently asked questions

Where does the data come from?

Atomic masses are the IUPAC standard atomic weights. Electronegativity uses the Pauling scale. Group, period, block, state and electron configuration follow the standard arrangement of the table.

What does a number in brackets mean?

For elements with no stable isotopes, such as technetium or the heaviest elements, there is no standard atomic weight. The number in brackets is the mass number of the most stable known isotope.

Why do some elements have no electronegativity?

Electronegativity describes how strongly an atom pulls electrons in a bond. Noble gases like helium and neon rarely form bonds, and many very heavy elements have never been measured, so they have no value.

What are the colors for?

Each color is a category, such as alkali metal, halogen or noble gas. Tap a category in the key to highlight only those elements, and tap it again to show all.

Can I use it offline?

Yes. Once the page has loaded, the whole table and its data work without an internet connection.

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