Compounds

Take on the identity of a simple compound such as H2O, and write a first-person narrative telling about your formation as a compound, with an illustration.

Draw and label diagrams of several different chemical reactions that result in compounds, and accompany each drawing with a brief description. 

Research and write an informational report about (1) one of the early scientists who discovered chemical compounds, (2) the uses of compounds in everyday life, or (3) how reactive elements that tend to form compounds are organized on the periodic table.

Look at the formula for a polyatomic compound (such as glucose, C6H12O6) and add up how many total atoms make up the compound. If some atoms were removed, tell how many atoms would remain, and state that it would no longer be glucose.

In a glass container, mix ¼ cup vinegar with 1 tablespoon of baking soda. Measure how long the reaction lasts. When it has stopped creating foam, add an antacid tablet such as a Rolaid or a Tums. Measure with a stopwatch to see how long it takes the mixture to completely deplete the bubbles.

Given the values for two isotopes of an element, calculate the atomic weight of an element by multiplying each isotope's mass by its percent abundance, and adding these values together. Check your answer with the atomic weight listed on the periodic table. For assistance, see a tutorial on atomic weight calculation and some sample problems.

A great variety of objects can be built up from a small set of pieces. Examples of pieces could include blocks, building bricks, or other assorted small objects. Different properties are suited to different purposes.

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. Examples of irreversible changes could include cooking an egg, freezing a plant leaf, and heating paper.

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, dissolving, and mixing that form new substances.

When two or more different substances are mixed, a new substance with different properties may be formed.

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 (e.g., crystals). Emphasis is on developing models of molecules that vary in complexity. Examples of extended structures could include sodium chloride or diamonds. Examples of simple molecules could include ammonia and methanol. Examples of models could include drawings, 3D ball and stick structures, or computer representations.

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. Examples of reactions could include burning sugar or steel wool, fat reacting with sodium hydroxide, and mixing zinc with hydrogen chloride.  Assessment may include analysis of the following properties: density, melting point, boiling point, solubility, flammability, and odor.

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. Emphasis is on natural resources that undergo a chemical process to form the synthetic material. Examples of new materials could include new medicine, foods, plastics, and alternative fuels.

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.  Examples of models could include drawings and diagrams. Examples of particles could include molecules or inert atoms. Examples of pure substances could include water and carbon dioxide (compounds.)

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.  The total number of each type of atom is conserved, and thus the mass does not change.  Emphasis is on law of conservation of matter and on physical models or drawings, including digital forms, that represent atoms.

Within individual organisms, food moves through a series of chemical reactions in which it is broken down and rearranged to form new molecules, to support growth, or to release energy. Emphasis is on describing that molecules are broken apart and put back together and that in this process, energy is released and on understanding that the elements in the products are the same as the elements in the reactants.