Chapter 2 Properties of Matter Classifying Matter Physical Properties Chemical Properties

What is Matter? Anything that takes up space and has mass.

There are different kinds of Matter Pure Substances Elements Compounds Mixtures Solutions Colloids Suspensions

A classification scheme for matter. Solution Suspension Colloid

Pure Substances A substance is either an element or a compound. Always has exactly the same composition. Every sample has the same properties because it has a fixed, uniform composition.

Elements If all the atoms in a substance are alike—then you are observing an element. 90 elements are naturally occurring, most are unstable.

Elements Each has a one or two letter symbol First letter is always capitalized, second letter is lower case Some have Latin names

Compounds Materials that are made up of 2 or more elements combined in a definite or fixed proportion. (i.e., salt, sugar, water) The ratio of different atoms, is always the same. Water (H2O) = 2-H + 1-0. Compounds, generally, take on characteristics of their own and do not resemble the individual elements that compose them. Can elements and compounds be separated by physical means? NO

Mixtures A mixture is two or more substances mixed together, that can be separated by physical means (i.e., salt, water). Composition varies. Two main types of mixtures: Heterogeneous Homogeneous

Homogeneous Mixtures Two or more substances blended evenly throughout. Also called solutions, which remain constantly and uniformly mixed. Examples: Soda Vinegar

Heterogeneous Mixtures Do not always contain the same proportions of each ingredient. Not every part of the mixture has the same composition. Examples: Granite Dry soup mix Trail mix

Suspension Heterogeneous mixtures. Generally, there is a liquid with some sort of “stuff” that can settle out.

Colloids Colloids never settle. They are Heterogeneous Mixtures. These particles are big enough to scatter light. Examples: Milk Fog paint

Fog A colloid composed of water droplets suspended in the air. Particles in the air can scatter the light, making fog. (hard to see through) The scattering is known as the “Tyndall Effect”.

Physical Properties A physical property of a material is a characteristic that can be observed without changing the substances that make up or compose the material.

Physical Changes Change in: Shape State of matter (i.e., breaking chalk, freezing) When a physical change occurs, the actual substance does not change.

Some Physical Properties Describes: Appearance (Color, Shape) Measurements (Size) Density Melting point (State of Matter) Boiling point (State of Matter) Viscosity Conductivity Malleability Hardness

Using Physical Properties Physical properties can be used to separate mixtures. - Filtration - Distillation

Chemical Change The changing of one substance to another substance. Change in: Smell Foaming Light, sound, or heat Examples—rusting & burning Flammability Reactivity Change in color (Sometimes) Formation of a precipitate

Chemical Properties Are only seen when the substance is changing into a different substance.

Conservation of Mass Matter cannot be created or destroyed. A burning log. Where does the mass go?