Science w2 - Matter Learning Interaction and Chemical Reactions Study Guide

Definition of Matter: Matter is defined as anything that possesses mass and occupies physical space.
Definition of Elements: Elements are substances composed of only one specific type of atom.
Interaction Goal: The primary educational goal ( $470$ ) is to understand and explain how the interactions between different types of matter result in various reactions, specifically categorized as endothermic and exothermic.

Chemical Change (Chemical Reactions): * Substance Formation: Involves the creation of new substances that possess chemical properties distinct from the original reactants. * Atomic Level: The reaction occurs by changing the atomic structure of the matter involved. * Reversibility: Chemical changes are characterized as being irreversible. * Examples: * Frying an egg. * Photosynthesis. * Rust formation. * Digestion.
Physical Change (Physical Reactions): * State of Matter: Involves a change in the physical state of the matter (e.g., solid, liquid, gas) or its physical properties. * Substance Identity: No new substance is formed; it is simply a change in the state of the existing elements. * Reversibility: Physical changes are characterized as being reversible. * Examples: * Shredding material. * Cutting a carrot.

Atomic Rearrangement: Chemical reactions involve the rearrangement of atoms to form entirely new substances.
Chemical Bonds: The process involves both the breaking of existing chemical bonds and the formation of new chemical bonds.
Observational Indicators: A chemical reaction can be identified through several observable phenomena: * Irreversible color change: A permanent shift in the color of the substance. * Temperature change: The substance or surroundings becoming significantly hotter or colder. * Gas formation: Evidenced by the appearance of bubbles. * Precipitate formation: The formation of a solid (transcript notes "liquid forming" in the context of precipitate) from a solution. * Sensory changes: The production of specific sounds or smells.

Law of Conservation of Energy: This fundamental law states that energy cannot be created nor can it be destroyed.
Energy Definition: In a general sense, energy is the ability to perform work or cause a change. Within the specific field of chemistry, energy is defined as the movement of particles, which is expressed through heat.
Bond Energy Dynamics: * Bond Breaking: Requiring energy input; associated with endothermic processes. * Bond Formation: Resulting in the release of energy; associated with exothermic processes.

Exothermic Reactions: * Definition: Reactions that release heat into the surrounding environment. * Energy Flow: Energy is released when chemical bonds are formed. * Examples: * Burning wood (reaction with oxygen). * Combustion. * Elephant toothpaste experiment. * Hand warmers.
Endothermic Reactions: * Definition: Reactions that absorb energy from the surroundings in the form of heat. * Energy Flow: Energy is required and absorbed when chemical bonds are broken. * Examples: * Photosynthesis. * Cold packs.
Learning Goal ( $9091$ ): To explain exothermic and endothermic reactions and understand the relationship between these reactions and the Law of Conservation of Energy.

Assessment Skills: Focusing on writing a strong research question and understanding the constituent components of a scientific report.
Variables in Experimentation: A variable is defined as something that varies within an experiment. There are three primary types: * Independent Variable: The factor that is intentionally changed by the researcher (e.g., the specific icepack used). * Dependent Variable: The factor that is being measured to observe the effect of the change (e.g., the resulting temperature). * Controlled Variables: The parameters of the experiment that must be kept identical to ensure a fair test. Examples include: * Conducting the experiment on the same day. * Using the same type of thermometer. * Maintaining the same room, location, or environment. * Utilizing the same individuals to record data. * Using the same material to wrap the ice pack.