2.4 States and Properties of Matter General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake Chapter 2 Energy and Matter 2.4 States and Properties of Matter Lectures © 2013 Pearson Education, Inc.

Solids Solids have a definite shape. a definite volume. particles that are close together in a rigid pattern. particles that vibrate slowly in their fixed positions. Amethyst, a solid, is a purple form of quartz (SiO2).

Liquids Liquids have a definite volume, but not a definite shape. the same shape as their container. particles that are close together, but mobile. particles that move slowly in random directions.

Gases Gases do not have a definite shape. do not have a definite volume. take the same shape and volume as their container. have particles that are far apart. are composed of fast moving particles that have little attraction to each other.

A Comparison of Solids, Liquids, and Gases

Learning Check Identify each as a (S) solid, (L) liquid, or (G) gas. __ A. It has a definite volume, but takes the shape of the container. __ B. Its particles are moving very rapidly. __ C. It fills the volume of a container. __ D. It has particles in a fixed arrangement. __ E. It has particles that are close together and are mobile.

Solution Identify each as a (S) solid, (L) liquid, or (G) gas. __ A. It has a definite volume, but takes the shape of the container. __ B. Its particles are moving very rapidly. __ C. It fills the volume of a container. __ D. It has particles in a fixed arrangement. __ E. It has particles that are close together and are mobile. L G G S L

Physical Properties Physical properties are observed or measured without affecting the identity of a substance. include shape, physical state, boiling and freezing points, density, and color of that substance.

Physical Properties of Copper

Physical Change A physical change occurs in a substance if there is a change in the state. a change in the physical shape. no change in the identity and composition of the substance.

Physical Change Water is found in all three physical states, solid, liquid, and gas. Water changes state from a solid to a liquid and from a liquid to a gas as heat is added. Q: Is heat added or released when liquid water freezes?

Change of State: Melting and Freezing At the melting point, a solid is converted to a liquid. At the freezing point, a liquid is converted to a solid.

Change of State: Evaporation and Condensation At the boiling point, a liquid is converted to a gas. At the same temperature, a gas is converted to a liquid as heat is removed.

Heating Curve A heating curve represents changes in temperature and physical state as heat is added to a substance. A horizontal line represents a phase change; a diagonal line represents an increase in the temperature of the substance.

Cooling Curve A cooling curve represents changes in temperature and physical state as heat is removed from a substance. A horizontal line represents a phase change; a diagonal line represents a decrease in the temperature of the substance.

Change of State: Sublimation and Deposition Sublimation is the process that describes the physical change of a solid directly to a gas. Deposition is the process that describes the physical change of a gas directly to a solid.

Examples of Physical Change

Chemical Properties and Chemical Change Chemical properties describe the ability of a substance to change into a new substance. During a chemical change a new substance forms that has a new composition. new chemical and physical properties.

Example of Chemical Change Iron (Fe) nails react with oxygen (O2) to form rust (Fe2O3). Iron Fe Iron (III) oxide Fe2O3

Examples of Chemical Change

Summary of Chemical and Physical Properties and Changes

Learning Check Classify each of the following as a (1) physical change or (2) chemical change. A. __ burning a candle B. __ ice melting on the street C. __ toasting a marshmallow D. __ cutting a pizza E. __ polishing a silver bowl

Solution Classify each of the following as a (1) physical change or (2) chemical change. A. __ burning a candle B. __ ice melting on the street C. __ toasting a marshmallow D. __ cutting a pizza E. __ polishing a silver bowl 2 1 2 1 2