An atom is the smallest unit of matter that retains the properties of an element.

Subatomic particles include protons, neutrons, and electrons.

Protons have a negative charge and are found in the nucleus of an atom.

Neutrons have no charge and are found outside the nucleus of an atom.

Electrons are positively charged and orbit the nucleus of an atom.

An element is a substance that cannot be broken down into simpler substances by chemical means.

A molecule is the smallest unit of a compound.

Pure substances have a fixed composition and cannot be separated by physical means.

A compound is made up of three or more different elements chemically combined.

Physical properties describe characteristics of a substance that can be observed without changing its chemical composition.

Physical changes alter the chemical composition of a substance.

Chemical properties describe how a substance reacts with other substances.

Chemical changes involve a change in the chemical composition of a substance.

The Law of Conservation of Matter states that matter cannot be created or destroyed, only rearranged.

Mass is a measure of the amount of matter in an object, while weight depends on the gravitational force acting on the object.

Volume is the amount of space occupied by an object or substance.

Density is the mass of an object divided by its volume.

A physical change alters the chemical composition of a substance.

Plasma is a state of matter that consists of uncharged particles and is commonly found in stars and lightning.