The 118 elements of the periodic table are divided into 11 categories based on their chemical and physical properties.
38 elements
Transition metals are d-block elements occupying groups 3-12 of the periodic table. They are characterized by partially filled d-orbitals, which give them unique properties: variable oxidation states, ability to form colored compounds, and catalytic activity.
Partially filled d-orbitals and variable oxidation states15 elements
Actinides are 15 chemical elements with atomic numbers from 89 (actinium) to 103 (lawrencium). All actinides are radioactive. Thorium and uranium occur in nature, the rest are synthetic. They are important for nuclear energy and weapons.
Radioactivity and filling of 5f orbitals15 elements
Lanthanides are 15 chemical elements with atomic numbers from 57 (lanthanum) to 71 (lutetium). They are characterized by filling of 4f orbitals and very similar chemical properties. Together with scandium and yttrium, they are called rare earth elements.
Filling of 4f orbitals and +3 oxidation state11 elements
Post-transition metals are a group of metallic elements in the p-block, located after transition metals in the periodic table. They include aluminum, gallium, indium, thallium, tin, lead, and bismuth. They are softer than transition metals and have lower melting points.
Soft metals with low melting points7 elements
Metalloids are elements that have properties of both metals and nonmetals. They include boron, silicon, germanium, arsenic, antimony, tellurium, and polonium. They are the foundation of modern electronics as semiconductors.
Semiconductor properties and intermediate conductivity7 elements
Noble gases are six chemical elements in group 18: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). They are characterized by a completely filled outer electron shell, which makes them chemically inert.
Completely filled outer electron shell and chemical inertness7 elements
Nonmetals are elements that lack typical metallic properties. They include hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, and selenium. They are the basis of organic compounds and life on Earth.
Poor conductivity of electricity and heat6 elements
The most reactive metals in the periodic table. All elements in this group have one electron in their outer shell, making them extremely active in chemical reactions.
soft metals6 elements
Alkaline earth metals are six chemical elements in group 2 of the periodic table: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). They have two valence electrons and form ions with a +2 charge.
Two valence electrons and +2 oxidation state6 elements
Halogens are five chemical elements in group 17: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The name comes from Greek 'halos' (salt) and 'genos' (to produce). They are extremely reactive and form salts with metals.
Seven valence electrons and high reactivity0 elements
This category includes superheavy elements whose chemical properties have not yet been experimentally investigated. Due to extremely short lifetimes and synthesis difficulty, their properties are only predicted theoretically.
Experimentally unconfirmed chemical propertiesElement classification is based on their electron configuration, chemical reactivity, and physical properties. Metals (alkali, alkaline earth, transition, post-transition, lanthanides, actinides) make up the majority of elements. Nonmetals, halogens, and noble gases have unique properties. Metalloids occupy an intermediate position between metals and nonmetals.