What is the difference between elements, compounds and mixtures including the type and arrangement of particles?

Atoms, elements, compounds, and mixtures are all forms of matter. Matter is defined as anything that has mass and volume.

Atoms, elements, and compounds are all pure substances. A pure substance is made of only one type of particle. However, mixtures are made of more than one pure substance that do not chemically combine.

An atom is the smallest unit of matter. Atoms are composed of three subatomic particles. The three subatomic particles of an atom are protons, neutrons, and electrons. The protons and neutrons are found within the central nucleus of an atom. The electrons move around the nucleus in either an orbital or cloud.

Compounds are composed of two or more atoms of different elements. The atoms that make up compounds  are chemically bound via either ionic, covalent, or metallic bonds. The ratio of the atoms within a compound never changes. For example, water (H2O) is a compound. Water always contains two hydrogen atoms and one oxygen atom. The shape of a compound is dependent on the type and number of atoms that it contains.

Mixtures are made of combinations of different substances. The quantity and arrangement of the substances that make up a mixture can fluctuate. Trail mix and salads are examples of mixtures.