Classification of Matter: Elements, Compounds, and Mixtures

Classification of Matter

Physical Properties of Compounds vs. Elements

The physical properties of compounds are often very different from those of the elements that compose them. When elements chemically combine to form compounds, their individual properties are lost and new properties emerge due to the formation of chemical bonds and new molecular structures.

• Element: A pure substance consisting of only one type of atom. Examples include carbon and oxygen.

• Compound: A substance formed when two or more elements chemically bond in fixed proportions. Examples include carbon monoxide (CO) and calcium bromide (CaBr2).

• Physical Properties: Characteristics such as melting point, boiling point, color, and density.

• Example: Sodium (a soft, reactive metal) and chlorine (a poisonous gas) combine to form sodium chloride (table salt), which is a safe, edible compound.

Additional info: The change in properties is due to the rearrangement of atoms and the formation of new chemical bonds.

Classification of Substances

Elements, Compounds, and Mixtures

All matter can be classified as elements, compounds, or mixtures based on its composition.

• Element (E): Pure substance made of one kind of atom.

• Compound (C): Pure substance made of two or more elements chemically combined.

• Mixture (M): Physical blend of two or more substances, not chemically combined.

Substance	Classification
carbon	Element (E)
carbon monoxide	Compound (C)
carbon + oxygen	Mixture (M)
calcium bromide	Compound (C)
hamburger	Mixture (M)
glass of water	Mixture (M)
sugar	Compound (C)
oxygen	Element (E)
salt water	Mixture (M)
brass	Mixture (M)
fruit punch	Mixture (M)
7 grain bread	Mixture (M)

Additional info: Brass is an alloy (mixture of copper and zinc); salt water is a solution (mixture of salt and water).

Types of Mixtures: Homogeneous vs. Heterogeneous

Classification of Mixtures

Mixtures can be further classified based on their uniformity:

• Homogeneous Mixture (HOM): Has a uniform composition throughout; also called a solution.

• Heterogeneous Mixture (HET): Has a non-uniform composition; different parts can be seen.

Mixture	Type
sparkling wine (champagne)	Heterogeneous (HET)
dirt	Heterogeneous (HET)
air	Homogeneous (HOM)
gasoline	Homogeneous (HOM)
wood	Heterogeneous (HET)
brass	Homogeneous (HOM)
well stirred sugar water	Homogeneous (HOM)

• Example: Air is a homogeneous mixture of gases; dirt is a heterogeneous mixture of soil particles, organic matter, and minerals.

Additional info: Sparkling wine is considered heterogeneous due to the presence of bubbles (gas in liquid).