Click any element to view full details · Search or filter to explore all 118 elements
Jump into the quiz below and test your knowledge of the periodic table — three modes, instant scoring.
Select up to three elements from the periodic table above (tap ⇄ Compare on any element) to see them side by side across fourteen properties.
A quick reference for students: the history behind the table, how to read it, and the vocabulary chemists use every day.
Dmitri Mendeleev published the first widely recognized periodic table in 1869, arranging known elements by atomic weight and leaving gaps for elements yet to be discovered. Later, Henry Moseley's work on atomic number gave the table its modern ordering principle.
Each cell shows an element's atomic number, symbol, name, and atomic mass. Rows are periods, columns are groups. Color indicates chemical category — metals on the left, nonmetals on the right, metalloids along the dividing line.
Every atom has a nucleus of protons and neutrons surrounded by electrons arranged in shells. The number of protons defines the element; the arrangement of outer electrons determines how it reacts with others.
A group is a vertical column of 18. Elements in the same group share the same number of valence electrons, giving them similar chemical behavior — for example, Group 1 alkali metals all react vigorously with water.
A period is a horizontal row. Moving across a period, atomic number increases by one each step and electrons fill the same outer shell, gradually changing the element's properties from metallic to nonmetallic.
The table is divided into s, p, d, and f blocks based on which electron subshell is being filled last. The f-block elements — lanthanides and actinides — are pulled out below the main table purely to keep it a manageable width.
Pick a quiz mode and answer as many rounds as you like. Your score is tracked below.
Three quick tools: look up atomic mass, calculate molecular weight from a formula, and inspect electron configurations.