Periodic Table Explorer
Click any element to see atomic number, mass, electron configuration and uses.
Frequently asked questions
How is the periodic table organized?
Elements are arranged by increasing atomic number (number of protons). They are placed in rows (periods) and columns (groups). Elements in the same group share similar chemical properties because they have the same number of electrons in their outermost shell.
What do the colours represent?
The colours indicate element categories: alkali metals (red) are highly reactive; alkaline earth metals (orange) are reactive but less so; transition metals (yellow) include iron, copper, gold; metalloids (green) have properties of both metals and nonmetals; nonmetals (blue) include carbon and oxygen; noble gases (purple) are mostly inert.
What is atomic mass?
Atomic mass (also called atomic weight) is the average mass of atoms of an element, measured in atomic mass units (u or amu). It accounts for the natural abundance of different isotopes. It differs from mass number, which is the total of protons and neutrons in one specific isotope.
What is electron configuration?
Electron configuration describes how electrons are distributed among energy levels (shells) in an atom. For example, Sodium (Na) has configuration 2,8,1 — meaning 2 electrons in the first shell, 8 in the second, and 1 in the third. The outermost electrons (valence electrons) determine reactivity.
How many elements are there?
As of 2024, there are 118 confirmed elements. Elements 1–94 occur naturally; elements 95–118 are synthetic (man-made) and are typically unstable, decaying quickly. The heaviest confirmed element is Oganesson (Og, element 118), synthesized in 2002.