Science Lecture Notes Review

Flashcards about Chemistry and Physics

Chemical Change

A change in which new substances are formed, usually irreversible, involving the breaking or making of chemical bonds between atoms. Signs include color change, burning, temperature change, explosion, odor, or bubbles.

Physical Change

A change in appearance where no new substance is formed, it can be reversed, and no chemical bonds are formed or broken. It involves a change in state, shape, or size.

Law of Conservation of Mass

Mass is not created or destroyed in a chemical reaction. The total mass of reactants equals the total mass of products.

Reactants

The starting materials in a chemical reaction.

Products

The substances created in a chemical reaction.

Exothermic Reaction

A reaction that releases energy to the surroundings, often measured with a thermometer. Examples include combustion, precipitation, digestion, respiration, and corrosion.

Endothermic Reaction

A reaction that absorbs energy from the surroundings, causing the surroundings to get colder. Requires bonds to break and is measured with a thermometer. Examples include photosynthesis and electrolysis.

Respiration

A chemical and exothermic reaction that breaks down glucose to release energy slowly. The equation is: glucose + oxygen → carbon dioxide + water + energy.

Digestion

A chemical and exothermic (hydrolysis) reaction where water breaks large food molecules into smaller, absorbable molecules.

Combustion

A process where a substance burns in oxygen, releasing heat, light, CO₂, and water. The equation is: fuel + oxygen → CO₂ + water + energy.

Corrosion

A process where a metal reacts with the environment (water and oxygen). Salt speeds it up. Example: iron rusting. The equation is: metal + water → metal hydroxide + hydrogen gas.

Decomposition

A process where a compound breaks into simpler substances, requiring energy (heat, light, or electricity). Elements can't decompose, but compounds can. Example: water → hydrogen + oxygen.

Precipitation

A reaction where two solutions react to form an insoluble solid (precipitate).

Acid-Base Reaction (Neutralization)

A reaction between an acid and a base to form water and a salt: Acid + Base → Salt + Water.

Acid-Metal Reaction

A reaction between an acid and a metal to produce hydrogen gas and a salt: Acid + Metal → Salt + Hydrogen Gas.

Acid-Carbonate Reaction

A reaction between an acid and a carbonate to produce a salt, water, and carbon dioxide gas: Acid + Carbonate → Salt + Water + Carbon Dioxide.

Rate of Reaction

The speed at which a reaction occurs, indicating how quickly reactants turn into products.

Catalyst

A substance that increases the rate of a chemical reaction without undergoing any permanent chemical change.

Collision Theory

Particles must collide with enough energy and the correct orientation to react. More successful collisions result in a faster reaction.

Validity

In scientific experiments, it refers to the control of variables to ensure the experiment measures what it intends to measure.

Reliability

In scientific experiments, it indicates the consistency of results, achieved through repetition.

Accuracy

In scientific experiments, it refers to how close the results are to the correct or known values.

Newton's First Law

Every object in motion will remain in motion and every object at rest will remain at rest unless there is an external force. This describes inertia.

Newton's Second Law

Force (newtons) = mass (kg) x acceleration (m/s²), F= M x A.

Newton's Third Law

Every action has an equal and opposite reaction.

Relative Motion

How motion is observed from different points of view.

Speed

A measure of distance over time.

Velocity

The measure of displacement over time, including direction (Velocity =displacement/time).

Scalar Quantity

A quantity that only has magnitude with no direction. Measured with values or numbers, e.g., speed, temperature, time.

Vector Quantity

A quantity that has both magnitude and a direction, e.g., velocity, displacement, acceleration, and momentum.

Distance

How far something has traveled; it is a scalar quantity.

Displacement

Measures the shortest distance and it is a vector quantity. If the origin and displacement are the same then displacement is zero.

Acceleration

Rate at which velocity changes, either in speed, direction, or both.