Eighth Grade Chemistry

Here are the scientific concepts:

• 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.
• Each pure substance has characteristic physical and chemical properties (for any bulk quantity under given conditions) that can be used to identify it.
• 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.
• Solids may be formed from molecules, or they may be extended structures with repeating subunits (e.g., crystals).
• The changes of state that occur with variations in temperature or pressure can be described and predicted using these models of matter.
• 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 term “heat” as used in everyday language refers both to thermal motion (the motion of atoms or molecules within a substance) and radiation (particularly infrared and light). In science, heat is used only for this second meaning; it refers to energy transferred when two objects or systems are at different temperatures.
• The relationship between the temperature and the total energy of a system depends on the types, states, and amounts of matter present.
• The total number of each type of atom is conserved, and thus the mass does not change.
• Some chemical reactions release energy, others store energy.

By the end of the labs in this unit, students will be able to:

• Predict the results of an experiment of a simple chemical reaction based on electron states of atoms, trends of the periodic table, and knowledge of the patterns of chemical properties. (For example: predict what happens in the reaction of sodium and chlorine, or of carbon and oxygen, or carbon and hydrogen...)
• Analyze and interpret data on the properties of substances before and after they interact to determine if a chemical reaction has occurred.
• Show using a model how the number of atoms doesn't change in a reaction and therefore mass is conserved.
• Design an experiment that releases or absorbs thermal energy by a chemical process.
• Differentiate observation from inference (interpretation) and know scientists’ explanations come partly from what they observe and partly from how they interpret their observations.
• Measure and estimate the length and volume of objects.
• Formulate and justify predictions based on cause-and-effect relationships.
• Conduct multiple trials to test a prediction and draw conclusions about the relationships between predictions and results.
• Construct and interpret graphs from measurements.
• Follow a set of written instructions for a scientific investigation.