IB Chemistry - The Periodic Table

Periodic Table

An arrangement of elements by increasing atomic number and recurring chemical properties, organized in periods (rows) and groups (columns).

Valence Electrons

Electrons in the outermost energy level of an atom, determining an element's chemical properties.

Mendeleev's Periodic Law

States that the chemical properties of elements are a periodic function of their atomic weights.

Dobereiner's Triads

Groups of three elements with similar properties, where the atomic mass of the middle element is approximately the mean of the other two.

Newland's Law of Octaves

Every eighth element exhibits properties similar to the first, based on arranging elements by increasing atomic mass.

Atomic Radius

The distance from the nucleus to the outermost electron shell, decreasing across periods and increasing down groups.

Ionization Enthalpy

Energy required to remove an electron from an isolated gaseous atom, increasing across periods and decreasing down groups.

Electron Gain Enthalpy

Energy change when an atom gains an electron to form a monovalent anion, increasing across periods and decreasing down groups.

Electronegativity

Atom's ability to attract shared electrons in a covalent bond, increasing across periods and decreasing down groups.

Modern Periodic Law

Properties of elements are a periodic function of their atomic numbers, as proposed by Henry Moseley.