Chemical Interactions Unit

CHEMICAL INTERACTIONS UNIT

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Investigation #1 - Substances

Students are introduced to chemistry lab tools and procedures.  They experience chemical reactions and learn three ways to identify chemical substances: common name, chemical name, and chemical formula.  They use macroscopic evidence from reactions to identify reactants.

Essential Question: How can unknown substances be identified?

Guiding Questions:  What is a substance?  How are substances represented?   What is a chemical reaction?  How can you tell a chemical reaction has occurred? What tests can help you identify an unknown substance?

 

Investigation #2 - Elements

Students learn that elements are the fundamental substances from which all matter on Earth is made.  They study the periodic table to become familiar with the 90 naturally occurring elements and search product ingredient lists for elements they contain.

Essential Question: What are substances made of?

Guiding Questions: What is an element?  How are elements represented? What is the periodic table and how is it organized?  How can you tell what elements are in a substance?  What are some elements found in common household products?  What elements are  most abundant in the sun, Earth, ocean, atmosphere, and living things?

 

Investigation #3 - Particles

Students investigate the macroscopic properties of gas and develop a particulate model to describe the invisible composition and interactions that account for the observable behaviors of gas.

Essential Question:  How do gases behave?

Guiding Questions:  What are elements, substances, and all matter made up of? How do we know that gases are matter?  How do the particles in a gas move, and what is in between those particles?  What happens to a gas when a force is applied or withdrawn?


Investigation #4 - Kinetic Energy

Students observe expansion and contraction of solids, liqids, and gases, and explain the phenomena in terms of kinetic theory - the constant motion of particles.

Essential Question:  How do particles move?

Guiding Questions:  What is kinetic energy?  What is the relationship between kinetic energy and heat?  What is the difference between compression and contraction?  What happens to the particles in a GAS when it heats up or cools down?  What happens to the particles in a LIQUID when it heats up or cools down?  What happens to the particles in a SOLID when it heats up or cools down?  How does a thermometer work?

 

Investigation #5 - Energy Transfer

Students experience the effects of energy transfer and learn to conceptualize the process of energy transfer as changes of particle kinetic energy resulting from particle collisions.  Students are introduced to calories to measure heat and discover that energy is conserved.  

Essential Question:  How does energy transfer?

Guiding Questions:  How is final temperature calculated when substances of different temperatures are mixed?  What is conduction and how does it affect the heating and cooling of materials?  What is the difference between temperature and heat?  How is energy transfer calculated? 


Investigation #6 - Heat of Fusion

Students conduct experiments to determine the amount of heat needed to convert a mass of ice at zero degrees Celsius to a mass of liquid water at zero degrees Celsius.  

Essential Question:  How is energy transfer affected by heat of fusion?

Guiding Questions:  How is heat of fusion defined?  How is heat of fusion calculated?  What is the heat of fusion for water?  Do all substances have the same heat of fusion?  Why does it seem as if energy is lost when solids become liquids?

 

Investigation #7 - Phase Change

Students experience three common phases (states) of matter - solid, liquid, and gas - and investigate the conditions that induce substances to change from one phase to another.  

Essential Question:  How does energy cause substances to change phase?

Guiding Questions:  What are the 3 common phases of matter?  How do particles move in solids, liquids, and gases? How is "change of phase" defined? What are the 6 processes that cause phase change? What is the difference between dissolving and melting? How do particles behave differently when matter changes phase?

 

Investigation #8 - Solutions

Students compare aqueous mixtures, one with a soluble solid and one with an insoluble solid.  They then dissolve table salt and Epsom salts to determine saturation and discover that different substances have different solubilities.  In the last part of the investigation, students engage the concept of concentration, the ratio of solute to solvent in a solution.  

Essential Question:  What are the characteristics of solutions?  

Guiding Questions:  What is a mixture?  What is a solution?  By what process do solutions form?  What happens on the particle level when solutions form? What is a saturated solution?  How much solvent and solute are needed to make a saturated solution?  What is concentration?  What is the relationship between concentration and mass?  How can the concentration of a solution be determined?


Investigation #9 - Reaction

Students blow bubbles into limewater, observe the precipitate, and move atom tiles (representations) to simulate the rearrangement of atoms to form new substances (particles).  Students conduct two other reactions - hydrochloric acid/baking soda and an antacid neutralization reaction - and learn to balance chemical equations.  

Essential Question: What happens to the atoms in substances when chemical reactions occur?  

Guiding Questions:  What are atoms and compounds?  How do molecules and ionic compounds form?  How are chemical formulas and balanced equations used to represent chemical reactions?  How can baking soda and HCl be used to confirm that atoms are not created or destroyed?  How can HCl and antacid tablets be used to confirm that atoms are not created or destroyed?


Investigation #10 - More Reactions

Students conduct more chemical reactions, learning about limiting factors and reactants in excess.  They observe the oxidation of iron (rusting) and confirm the concentration of oxygen in air by assuming that oxygen is the limiting factor.