States of Matter

From a book or pictures, identify common objects in their states such as ice cubes, a glass of juice or helium in a balloon.

Explain how temperature affects the state of matter and how some matter, such as water, can move in and out of states.

Most people think that there are only three states of matter, but there are actually five. Find out what the other two states are and describe when they happen, how they happen and at what temperature they happen.

List, sort, and count all of the solids, liquids and gases that your class can find, using a picture or photo that contains examples of the three states of matter. Create a graph of the findings.

Measure how long it takes for an ice cube to completely change to liquid state at room temperature. Compare to the length of time it takes to change an equal amount of water to water vapor at room temperature.

Absolute Zero is a temperature at which there is absolutely no molecular activity. Use this interactive scale to determine common temperatures of things found in nature and around us. With teacher help, calculate differences for temperatures above and below freezing.

Different kinds of matter exist and many of them can be solid, liquid, or gas, depending on temperature. Matter can be described and classified by its observable properties.

Different properties are suited to different purposes. Examples of properties could include strength, flexibility, hardness, texture, and absorbency.

Heating or cooling a substance may cause changes that can be observed. Sometimes these changes are reversible, and sometimes they are not. Examples of reversible changes could include materials such as water and butter at different temperatures.

Water exists as solid ice and in liquid form.

Matter of any type can be subdivided into particles that are too small to see, but even then, the matter still exists and can be detected by other means. A model showing that gases are made from matter particles that are too small to see and are moving freely around in space can explain many observations, including the inflation and shape of a balloon and the effects of air on larger particles or objects. Examples of evidence supporting a model could include adding air to expand a basketball, compressing air in a syringe, dissolving sugar in water, and evaporating salt water.

The amount (weight) of matter is conserved when it changes form, even in transitions in which it seems to vanish. No matter what reaction or change in properties occurs, the total weight of the substances does not change. Examples of reactions or changes could include phase changes.

Measurements of a variety of properties can be used to identify materials.  Examples of materials to be identified could include baking soda and other powders, metals, minerals, and liquids. Examples of properties could include color, hardness, reflectivity, electrical conductivity, thermal conductivity, response to magnetic forces, and solubility.

Nearly all of Earth’s available water is in the ocean. Most freshwater is in glaciers or underground; only a tiny fraction is in streams, lakes, wetlands, and the atmosphere.

Substances are made from different types of atoms, which combine with one another in various ways. Atoms form molecules that range in size from two to thousands of atoms.  Solids may be formed from molecules, or they may be extended structures with repeating subunits (crystals). Emphasis is on developing models of molecules that vary in complexity. Examples of simple molecules could include ammonia and methanol. Examples of models could
include drawings, 3D ball and stick structures, or computer representations.

Each pure substance has characteristic physical and chemical properties that can be used to identify it.  Substances react chemically in characteristic ways. In a chemical process, the atoms that make up the original substances are regrouped into different molecules, and these new substances have different properties from those of the reactants. Analysis may include the following properties: density, melting point, boiling point, solubility, flammability, and odor.

Gases and liquids are made of molecules or inert atoms that are moving about relative to each other. In a liquid, the molecules are constantly in contact with others; in a gas, they are widely spaced except when they happen to collide. In a solid, atoms are closely spaced and may vibrate in position but do not change relative locations. The changes of state that occur with variations in temperature or pressure can be described and predicted using these models of matter.  Emphasis is on qualitative molecular-level models of solids, liquids, and gases to show that adding or removing thermal energy increases or decreases kinetic energy of the particles until a change of state occurs. Examples of models could include drawings and diagrams. Examples of particles could include molecules or inert atoms. Examples of pure substances could include water, carbon dioxide, and helium. 

A solution needs to be tested and then modified on the basis of the test results in order to improve it. Although one design may not perform the best across all tests, identifying the characteristics of the design that performed the best in each test can provide useful information for the redesign process — that is, some of the characteristics may be incorporated into the new design. The iterative process of testing the most promising solutions and modifying what is proposed on the basis of the test results leads to greater refinement and ultimately to an optimal solution.

Temperature is a measure of the average kinetic energy of particles of matter. The relationship between the temperature and the total energy of a system depends on the types, states, and amounts of matter present. The amount of energy transfer needed to change the temperature of a matter sample by a given amount depends on the nature of the matter, the size of the sample, and the environment. Examples of experiments could include comparing final water temperatures after different masses of ice melted in the same volume of water.

Emphasis is on the ways water changes its state as it moves through the multiple pathways of the hydrologic cycle. Water continually cycles among land, ocean, and atmosphere via transpiration, evaporation, condensation, crystallization, percolation, and precipitation.