How to read the periodic table (a complete beginner's guide)

Published June 2026 · 5 min read

The periodic table organizes all known chemical elements by their atomic number, electron configuration, and recurring chemical properties. Once you understand its layout, reading it becomes simple.

Rows are called periods

Each horizontal row is a period. Elements in the same period have the same number of electron shells. As you move left to right across a period, atomic number increases by one each step.

Columns are called groups

Each vertical column is a group. Elements in the same group share similar chemical behavior because they have the same number of electrons in their outermost shell.

Atomic number and atomic mass

The atomic number (usually shown above the symbol) tells you how many protons the element has. The atomic mass (usually shown below) is the average mass of the element's naturally occurring isotopes.

Color categories

Most interactive periodic tables use color to separate element categories — alkali metals, transition metals, nonmetals, noble gases, and more. This makes it easy to spot patterns at a glance.

Try it yourself

Explore the interactive periodic table and click any element to see its full details, or test your knowledge with our periodic table quiz game.