Classification of Matter

Objectives Classify matter as a pure substance or a mixture Explain the difference between an element and a compound Distinguish between homogeneous and heterogeneous mixtures Describe three ways that components of mixtures can be separated Contract pure substances and mixtures

Important Vocabulary Pure substance Element Compound Chemical symbol Mixture Heterogeneous Homogenous Solution Solvent Solute Aqueous solution Alloy Chemical Formula Filtration Distillation

Is matter that has definite chemical and physical properties There are two types of pure substances: ◦ Elements ◦ Compounds Pure Substances

Is the simplest form of matter that has a unique set of properties They can NOT be broken down into simpler substances by chemical means Examples? How elements are in the Periodic Table? How many of them have official names? They have distinct chemical symbols Element

Chemical Symbols Are used to represent elements Chemical symbol is a one-letter or two- letter code The first letter is always capitalized and the second letter must be lowercase. They have been around since ancient time in various formats The symbols used today are based on a system developed by Swedish chemist, Jons Jacob Berzelius He based his system on the Latin names of elements.

Jons Jacob Berzelius 1779 –1848

Latin Named Elements

Other Element Name Origins

Is a substance that contains two or more elements chemically combined in a fixed proportion Compounds have characteristic properties and compositions They can be broken down into their elements by chemical means They are represented by formulas, which is a group of chemical symbols that shows the type of elements and their amount in a compound Examples?Compound

Properties of Compounds In general, the properties of compounds are quite different from those of their component elements For example: Sucrose C 12 H 22 O 11 (table sugar) ◦ Elements: Carbon, Hydrogen & Oxygen  Carbon- is black, tasteless solid  Hydrogen- is a colorless, odorless gas, explosive with a spark  Oxygen-is a colorless odorless gas, essential for life Properties of Sucrose? How about salt? (NaCl)

Are a combination of two or more pure substances physically combined The proportions of the ingredients can vary The properties of mixtures can change as well For example: salad, Kool-Aid, concrete, air, & alloys An alloy is a mixture of metals in various proportions to influence density, color, and strength (Table 1 p.23) Mixtures can be classified in two waysMixtures

Heterogeneous Mixtures Are mixtures that do NOT have a uniform composition throughout (unevenly mixed) Examples: ◦ Water & Flour ◦ Sand & Salt ◦ Salad ◦ Chocolate chip cookie dough Different regions of this type of mixture have different properties

Homogeneous Mixtures Are mixtures that have a uniform structure or composition throughout Examples: ◦ Gasoline ◦ Syrup ◦ Air ◦ Vinegar ◦ Tomato soup Properties are also uniform throughout the mixtures Also called a solution

Solutions Are homogeneous mixtures Most are liquids Each solution has two parts: A solute, which is the substances that is dissolved A solvent, which is the substance that does the dissolving If the solvent is water, it is called an aqueous solution Examples: ◦ Rubbing alcohol ◦ Saltwater ◦ Air ◦ Stainless steel

Phases Is used to describe any part of sample with uniform composition and properties Homogeneous mixtures consist of one phase Heterogeneous mixtures consist of two or more phases For example: oil and water mixture

Some mixtures are easier to separate than others Differences in physical properties can be used to separate mixtures Techniques for separation include ◦ Filtration ◦ Distillation ◦ Chromatography Separating Mixtures

Filtration Is the process that separates a solid from the liquid in a heterogeneous mixture For example: making coffee & straining pasta

Distillation Is the process where a liquid is boiled to produce a vapor that is then condensed into a liquid For example: distilling water to remove minerals In this case, the solid substances that were dissolved in the water remain in the distillation flask because their boiling points are much higher than water’s boiling point

Distillation Apparatus

Chromatography The mixture is dissolved in a fluid called the mobile phase, which carries it through a structure holding another material called the stationary phase. The various constituents of the mixture travel at different speeds, causing them to separate.

Breaking Down Compounds Physical separation methods used for mixtures do not work for compounds Because compounds are chemically combined, they require a chemical change to be broken down

Pure Substances Are elements or compounds Are elements or compounds Chemically combined Chemically combined Properties of compounds are different from their individual components Properties of compounds are different from their individual components Its components are in definite proportions or fixed Its components are in definite proportions or fixed Are HOG or HED Are HOG or HED Physically combined Physically combined Properties of mixtures are reflected by their components Properties of mixtures are reflected by their components Its composition can be in varying proportions Its composition can be in varying proportions Distinguishing Pure Substances & Mixtures Mixtures