The periodic table is a tabular arrangement of all known chemical elements, organized by increasing atomic number (number of protons). Elements are arranged in rows called periods (1–7) and columns called groups (1–18). Elements in the same group share similar chemical properties because they have the same number of valence electrons. The table is divided into blocks (s, p, d, f) based on electron configurations.

As of 2024, there are 118 confirmed elements in the periodic table, ranging from Hydrogen (atomic number 1) to Oganesson (atomic number 118). The first 94 elements occur naturally on Earth, while elements 95–118 are synthetic and have only been produced in laboratories. Element 119 (Ununennium) has not yet been synthesized.

Each element cell typically displays the atomic number (top, indicating the number of protons), the chemical symbol (one or two letters, e.g., "Fe" for Iron), and the atomic mass (weighted average of all naturally occurring isotopes). The element's full name is often included below the symbol.

Elements are grouped into 11 main categories: Alkali Metals (Group 1, highly reactive), Alkaline Earth Metals (Group 2), Transition Metals (Groups 3–12), Post-Transition Metals, Metalloids (properties between metals and nonmetals), Nonmetals, Halogens (Group 17, very reactive), Noble Gases (Group 18, inert), Lanthanides (rare earth metals, 57–71), Actinides (mostly radioactive, 89–103), and superheavy elements with unknown properties.

You can use the search bar at the top to find any element by typing its name (e.g., "Gold"), chemical symbol (e.g., "Au"), or atomic number (e.g., "79"). Matching elements will be highlighted while others are dimmed. You can also filter by category using the color-coded legend buttons. Click any element to see detailed information including electron configuration, electronegativity, and more.

Atomic mass (or atomic weight) is the weighted average mass of all naturally occurring isotopes of an element, expressed in atomic mass units (amu). The mass number is the total number of protons and neutrons in a specific isotope's nucleus. For elements with no stable isotopes (like Technetium or many actinides), the atomic mass is shown in brackets, representing the most stable isotope's mass number.

Lanthanides (elements 57–71) and Actinides (elements 89–103) belong to the f-block of the periodic table. They are traditionally placed below the main table to keep the table compact and readable. If inserted in their actual positions (in Group 3, Periods 6 and 7), the table would be extremely wide with 32 columns. Lanthanides are also called "rare earth elements," while most actinides are radioactive.

Only two elements are liquid at standard room temperature (around 25°C / 77°F): Mercury (Hg) and Bromine (Br). A few other elements have melting points very close to room temperature: Gallium (Ga, melts at ~30°C), Cesium (Cs, melts at ~28°C), and Francium (Fr, melts at ~27°C). Copernicium (Cn) is predicted to possibly be liquid at room temperature, but this has not been experimentally confirmed.