Pure Substances

Pure substances consist of the following Elements Compounds Pure Substances

Elements

Elements, the Simplest Substances An element is a pure substance that cannot be separated into simpler substances by physical or chemical means. Only One Type of Particle A substance in which there is only one type of particle is a pure substance. Elements are made of particles called atoms.

Properties of Compounds Each compound can be identified by its physical and chemical properties. + = + Properties: Compounds Versus Elements A compound has properties that differ from those of the elements that form it.

Breaking Down Compounds Compounds can be broken down into their elements or into simpler compounds by chemical changes. Methods of Breaking Down Compounds Sometimes, energy is needed for a chemical change to happen. Two ways to add energy are to apply heat and to apply an electric current.

Compounds in Your World Compounds in Nature Some compounds found in nature are proteins, carbon dioxide, and carbohydrates. Glucose: C6 H12 O6 Compounds in Industry Some compounds must be broken down for use in industry. Other compounds, are made in industry for use as medicines, food preservatives, and synthetic fabrics.

Mixtures

A mixture is a combination of two or more substances where there is no chemical combination or reaction.

Mixtures combine physically in no specific proportions. They just mix.

Solids, liquids and gases can be combined to create a mixture.

Solute and Solvent You make a mixture by adding at least one material to another. When you add material to a gas or liquid, the material you add is called the solute The material you are adding to is called the solvent.

When you create a mixture, there are no new substances formed When you create a mixture, there are no new substances formed. Each part of a mixture keeps its own properties.

Mixtures can be heterogeneous or homogeneous.

Heterogeneous mixtures are those where the substances are not distributed evenly. They usually involve a mixture of a solid in a solid. A mixture of stones in soil is an example of a heterogeneous mixture.

Here is another example

Homogeneous mixtures are those where the materials are evenly distributed throughout. Homogenized milk is an example.

Mixtures can be classified into three types: Suspension Colloid Solution Mixtures can be classified into three types:

Suspension mixtures have larger particles and are heterogeneous Suspension mixtures have larger particles and are heterogeneous. Most mixtures are suspension mixtures. Italian salad dressing is a good example.

Solutions are homogeneous mixtures that consist of microscopic particles and evenly spread out molecules.

Colloidal mixtures fall between suspension and solution mixtures Colloidal mixtures fall between suspension and solution mixtures. The ingredients in colloidal mixtures are smaller and usually homogeneous.

You can separate a simple mixture by physical means You can separate a simple mixture by physical means. No chemical reaction is needed.

In Summary