Topic 1: Matter: Types and Forms

Vocabulary flashcards covering core concepts of matter, pure substances, element classifications, physical and chemical properties, phase changes, and atomic structure based on chemistry lecture notes.

Matter

Anything that has mass and volume and makes up the universe, composed of atoms existing as a solid, liquid, or gas.

Chemistry

The study of matter and its properties, the changes that matter undergoes, and the energy associated with those changes.

Pure Substance

A homogeneous species made of one type of particle with fixed physical and chemical properties, existing as either a single element or a compound.

Element

A pure substance that cannot be broken down by chemical means into anything simpler, characterized by a unique number of protons in its atomic nucleus.

Compound

A species formed by the chemical combination of two or more different elements.

Atomic Elements

Elements that exist as isolated single atoms under normal conditions, restricted primarily to the noble gases.

Molecular Elements

Elements in which discrete particles containing a fixed number of two or more identical atoms are covalently bonded together.

Metallic Elements

Elements that exist as an infinite 3D network array of atoms with delocalised outermost electrons moving throughout the structure.

Network Covalent Elements

Elements such as carbon and silicon that form infinite network structures connected by localized covalent bonds between atoms.

Allotropes

Different structural forms of the same element that differ in the number of atoms in the molecule and/or the spatial arrangement of those atoms.

Malleability

The physical property describing the ability of a substance to be shaped when subjected to stress.

Ductility

The physical property describing the ability of a substance to be drawn or pulled into a wire.

Crystalline Solid

A solid whose constituent particles are arranged in an orderly geometric pattern over a long range.

Amorphous Solid

A solid whose constituent particles do not show a regular geometric pattern over a long range.

Sublimation

The phase change in which a solid transitions directly into a gas without forming a liquid in between.

Physical Property

A characteristic that a substance displays or measures without changing its chemical composition.

Chemical Property

A characteristic that a substance displays only by changing its chemical composition through a reaction or interaction with other substances.

Atom

An indivisible particle ranging from $0.1\,nm$ to $0.5\,nm$ in diameter that composes each element and consists of protons, neutrons, and electrons.

Atomic Number

The unique number of protons contained within the nucleus of an atom, which determines the identity of the element.

Mass Number

The total sum of protons and neutrons ($\Sigma\,\text{protons} + \Sigma\,\text{neutrons}$) in the nucleus of an atom.

Isotopes

Different forms of the same element that contain the same number of protons but different numbers of neutrons, resulting in different mass numbers.

Unified Atomic Mass Unit ($u$)

The SI unit of atomic mass defined by assigning a mass of exactly $12\,u$ to an atom of the $^{12}C$ isotope ($1\,u = 1.66054 \times 10^{-24}\,g$).