chemical

Element

A basic substance made of only one type of atom; cannot be simplified or broken down by chemical reactions.

Atom

The fundamental building block of matter, consisting of a dense central nucleus surrounded by orbiting electrons.

Symbol

A standard abbreviation for elements, based on their English names or from Latin/Greek origins.

Proton

A subatomic particle with a positive charge and a relative mass of 1 unit, determining the element's identity.

Neutron

A subatomic particle with no charge and a relative mass of 1 unit, stabilizes the nucleus.

Electron

A subatomic particle with a negative charge and negligible mass, moves rapidly in energy levels around the nucleus.

Atomic Number (Z)

The number of protons in an atom, which equals the number of electrons in a neutral atom.

Mass Number (A)

The sum of protons and neutrons in the nucleus of an atom.

Isotope

Atoms of the same element with different numbers of neutrons, leading to different mass numbers.

Relative Isotopic Mass

The mass of one atom of an isotope compared to 1/12th of the mass of a Carbon-12 atom.

Relative Atomic Mass (Ar)

The weighted average mass of an element's isotopes, calculated using their mass and abundance.

Valence Electrons

Electrons located in the outermost shell that determine an element's chemical reactivity.

Metal

Elements located on the left side of the periodic table, known for high melting points, ductility, and the tendency to lose electrons.

Non-metal

Elements located on the right side of the periodic table, typically gain electrons to form negative ions.

Maltaloids

Elements with intermediate properties between metals and non-metals.

Dmitri Mendeleev

The scientist who arranged elements by atomic mass and left gaps for undiscovered elements.

Alkali Metals

Group I metals, soft, low density, and increase in reactivity down the group.

Alkaline Earth Metals

Group II metals that are harder and denser, forming +2 ions.

Halogens

Group VII elements with varying physical states, decreasing reactivity down the group.

Noble Gases

Group 0 elements, chemically stable with duplet or octet electronic configuration.

Metallic Bonding

The electrostatic force between positive metal ions and delocalized electrons in a metallic lattice.

Cation

A positive ion formed when metal atoms lose valence electrons.

Anion

A negative ion formed when non-metal atoms gain electrons.

Ionic Bond

The strong electrostatic attraction between oppositely charged ions in an ionic compound.

Polyatomic Ion

An ion composed of multiple atoms that carry a charge.