Interactive Periodic Table

The periodic table is organized by increasing atomic number (number of protons). Elements are arranged in periods (horizontal rows) and groups (vertical columns). 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 configuration.

Elements are grouped into metals (alkali metals, alkaline earth metals, transition metals, post-transition metals, lanthanides, actinides), metalloids (elements with properties between metals and nonmetals like silicon and boron), and nonmetals (including halogens, noble gases, and other nonmetals like oxygen and carbon). Each category has distinct physical and chemical characteristics.

Lanthanides (elements 57-71) and actinides (elements 89-103) are f-block elements placed below the main table to keep the table compact and readable. If included in the main grid, the table would be 32 columns wide. They fit into period 6 and 7 respectively, at group 3. Lanthanides are also called rare earth elements and are crucial for modern electronics and magnets.

Electronegativity measures an atom's tendency to attract shared electrons in a chemical bond. The Pauling scale is most commonly used, ranging from about 0.7 (francium, least electronegative) to 4.0 (fluorine, most electronegative). Higher electronegativity means stronger electron attraction. Trends: electronegativity increases across a period (left to right) and decreases down a group.

As of 2024, there are 118 confirmed elements on the periodic table, from hydrogen (atomic number 1) to oganesson (atomic number 118). Elements 1 through 94 occur naturally on Earth, while elements 95-118 are synthetic and were created in laboratories. The most recently named elements are nihonium (113), moscovium (115), tennessine (117), and oganesson (118), all officially named in 2016.

Isotopes are variants of the same element that have the same number of protons but different numbers of neutrons. For example, carbon-12, carbon-13, and carbon-14 are all carbon isotopes. Some isotopes are stable, while others are radioactive and decay over time. The atomic mass shown on the periodic table is the weighted average of all naturally occurring isotopes of that element.

The atomic number (Z) is the number of protons in an atom's nucleus and uniquely identifies each element. The atomic mass (or atomic weight) is the average mass of an atom, measured in atomic mass units (amu), accounting for all naturally occurring isotopes. For example, carbon's atomic number is 6, but its atomic mass is approximately 12.011 amu due to the mixture of isotopes.