Periodic Table Explorer

The periodic table is an organised chart of all known chemical elements, arranged by atomic number (the number of protons). Elements in the same column share similar chemical properties.

The number of protons in the nucleus defines the element. For example, every atom with 6 protons is carbon, and every atom with 79 protons is gold, regardless of how many neutrons or electrons it has.

Atomic number is the count of protons in the nucleus. Atomic mass (or mass number) is the total of protons plus neutrons. For example, Carbon has atomic number 6 and atomic mass approximately 12 (6 protons + 6 neutrons).

Electron shells are energy levels around the nucleus where electrons are found. The first shell holds up to 2 electrons, the second up to 8, the third up to 18. Elements in the same row of the periodic table have the same number of shells.