8th Grade Mid-term Study Guide

These flashcards cover key vocabulary and concepts from the 8th grade mid-term study guide including laboratory safety, Newton's laws, waves, chemical reactions, and properties of acids and bases.

Goggles

Protective eyewear worn in laboratory settings to prevent eye injury.

Independent variable

The variable being changed in an experiment to observe its effect.

Dependent variable

The variable that is affected by changes; the one being measured.

Control variable

Any factor kept the same in an experiment; the constant.

Inertia

The tendency of an object to stay at rest or in motion unless acted upon by an external force.

Force

A push or pull exerted on an object.

Acceleration

The rate at which an object's velocity changes.

Balanced force

When two equal forces are applied to an object in opposite directions; the object does not move.

Net force

The sum of all forces acting on an object.

Newton's 1st Law

An object in motion will stay in motion, and an object at rest will stay at rest unless acted upon by an outside force.

Newton's 2nd Law (Formula)

F = m • a, where F is force, m is mass, and a is acceleration.

Wave

A pattern of motion that transports energy.

Crest

The highest point of a wave.

Trough

The lowest point of a wave.

Wavelength

The distance between one peak of a wave and the next.

Frequency

The number of cycles a wave completes in a given period of time.

Amplitude

The height or strength of a wave.

Electromagnetic wave

A wave that can transfer its energy through a vacuum.

Polarity

The separation of opposite charges within a molecule.

Acid

Any substance with a pH less than 7 that can turn blue litmus paper red.

Base

Any substance with a pH higher than 7 that can turn red litmus paper blue.

Chemical reaction

The process where reactants transform into new substances called products.

Exothermic reaction

A chemical reaction in which energy is released.

Endothermic reaction

A chemical reaction in which energy is absorbed.

Molecule

Two or more atoms joined together by chemical bonds.

Solution

A mixture in which a solid, liquid, or gas is evenly distributed within another substance.

Newton's 3rd Law

For every action, there is an equal and opposite reaction.

Friction

A force that opposes the motion of an object as it moves across a surface.

Gravity

An attractive force that exists between all objects with mass.

Velocity

The speed of an object in a specific direction.

Speed

The distance traveled per unit of time, calculated as (v = d / t).

Mechanical wave

A wave that requires a medium, such as air or water, to travel through.

Medium

The substance (solid, liquid, or gas) through which a wave travels.

Period

The time it takes for one complete wave cycle to pass a given point.

Scalar

A physical quantity that has only magnitude and no direction.

Vector

A quantity that has both magnitude and direction.

Reactant

A starting substance in a chemical reaction that undergoes change.

Product

A substance formed as a result of a chemical reaction.

pH Scale

A scale ranging from 0 to 14 used to measure how acidic or basic a solution is.

Solvent

The substance in a solution that dissolves the solute, usually present in the greatest amount.

Solute

The substance that is dissolved in a solution.

Compound

A substance made of two or more different elements chemically bonded together.

Mixture

A physical combination of two or more substances that are not chemically joined and can be separated.

Atom

The basic unit of a chemical element and the smallest constituent unit of ordinary matter.

Atomic Number

The number of protons in the nucleus of an atom, which determines the element's identity.

Law of Conservation of Mass

The principle stating that matter is neither created nor destroyed in a chemical reaction.

Hypothesis

A testable explanation or prediction for a scientific observation or question.

Theory

A well-substantiated explanation of some aspect of the natural world based on a body of evidence.

Data

Facts, figures, and other evidence gathered through observations during an experiment.