Classification of Matter Two Classifications of Matter v

Classification of Matter

Two Classifications of Matter v. Pure Substance v. Mixture

Pure Substance • A pure substance has the same composition throughout and does not vary from sample to sample.

Classification of Pure Substances v. Elements v. Compounds

Elements • Elements are the basic building blocks of matter • They can not be decomposed by a chemical change • Each element has a unique set of chemical and physical properties • All elements are composed of atoms ( the basic unit of matter) • Elements are represented by symbolsthe 1 st letter is always capitalized and the last letter is lower case (ex. Na)

Examples: Sodium Chlorine Properties of Na: • Solid • Grey metal • Reacts violently with water Properties of Cl: • Gas • Yellow • Poisonous

Let’s explore more elements and their properties:

Compounds v. Compounds are composed of two or more elements. v. Elements in a compound have had their physical and chemical properties altered as a result of being chemically bonded via a chemical reaction. v. Compounds can be decomposed into two or more simpler compounds or elements by a chemical change.

Compounds are represented by: • Chemical Formulas which use element symbols and subscripts to show which elements and how many are in the compound. • Ex. Na. Cl, Mg. Cl 2

Examples: • 2 Na + Cl 2 2 Na. Cl Properties of Na. Cl: Sodium Chloride • Solid • White • Does not react with water. **Notice how the unique properties of the elements in the compound have been changed.

Mixtures • A mixture contains more than one substance. • The composition of a mixture can vary from sample to sample; however, each component of a mixture retains its own unique physical and chemical properties. • Mixtures can be separated by physical means.

Classification of Mixtures v. Homogeneous v. Heterogeneous

Homogeneous Mixtures • Homogeneous mixtures are also known as solutions. • They have a uniform composition and the components can not be seen as separate. Lemonade Vinegar

Heterogeneous Mixtures • Heterogeneous mixtures do not have a uniform composition and the components can be seen as separate. Granite Pizza

Separation Techniques • Filtration • Distillation • Crystallization • Chromatography

Filtrations • Used to separate heterogeneous mixtures. • The mixture is poured through a piece of paper which allows the liquid part to pass and catches the solid portion.

Distillations • Used to separate homogeneous mixtures. • This technique takes advantage of different boiling points.

Crystallization • Used to separate homogeneous mixtures. • The liquid portion is allowed to evaporate and the solid portion remains behind as a crystal.

Chromotography • Separation occurs by allowing a mixture to flow along a stationary substance (usually chromotography paper).