Classification of Matter: Pure Substances, Mixtures, and Compounds

Matter

Anything that has mass and takes up space; can be a pure substance or mixture

Pure Substance

Same proportion of components; one set of properties (example: CO₂, Na)

Mixture

Composed of more than one substance

Homogeneous Mixture

Same throughout; one phase; particles < 1 µm (example: salt water, air)

Solution

Homogeneous mixture; particles don't settle or separate; no Tyndall effect (example: brass, sterling silver)

Colloid

Mixture with particles 1 nm - 1 µm; shows Tyndall effect; does not settle (examples: fog, mayonnaise)

Heterogeneous Mixture

Not the same throughout; multiple phases; particles > 1 µm

Suspension

Heterogeneous mixture; particles settle over time; shows Tyndall effect (example: silt in water, paint)

Tyndall Effect

Scattering of light by particles in a mixture

Element

Pure substance with only one type of atom; cannot be broken down (example: Li)

Metal

Good conductor of heat/electricity; malleable; ductile; lustrous; oxides form bases

Nonmetal

Poor conductor; brittle as solids; oxides form acids

Metalloid

Has properties of both metals and nonmetals (examples: B, Si, As)

Hydrogen

Unique element in a group of its own

Compound

Substance made of more than one type of atom; can be broken down

Chemical Species

Particles of matter (neutral atoms, molecules, ions)

Alloy

Mixture containing metals; typically hard (example: steel)

Metallic Character

Periodic trend; increases left and down the periodic table

Semiconductor

Poor conductor of electricity; can act as conductor under certain conditions (example: silicon)

Allotrope

Different forms of the same element (examples: O₂ vs O₃, diamond vs graphite)

Organic Compound

Contains C and H bonded together (example: methane, CH₄)

Binary Compound

Made of two elements (example: KCl)

Ionic Compound

Made of cations and anions (example: NH₄Cl)

Molecular (Covalent) Compound

Made of nonmetals sharing electrons (example: P₂O₅)

Acid

Compound with hydrogen ion bonded to an anion (example: HCl)

Base

Compound containing hydroxide (example: NaOH)

Salt

Ionic compound that is not a hydroxide (example: NaCl)