8th grade science eoc

Scientific Method

A process involving identifying a problem, forming a hypothesis, conducting experiments, collecting and analyzing data, drawing conclusions, and communicating findings.

Independent Variable

The factor you change in an experiment.

Dependent Variable

The factor you measure.

Control Variables

Factors that remain constant.

Theory

A well-tested explanation of observations (e.g., Theory of Evolution).

Law

A rule that describes a pattern in nature (e.g., Law of Gravity).

Replication

Another scientist repeats your experiment.

Repetition

Conducting multiple trials for accuracy.

Periodic Table

Elements arranged by atomic number (number of protons).

Groups (Columns)

Share similar properties (e.g., Group 1 = Alkali metals, very reactive).

Periods (Rows)

Elements gradually change properties from left to right.

Metals

Good conductors, malleable, ductile.

Nonmetals

Poor conductors, brittle.

Metalloids

Have properties of both metals and nonmetals.

Atomic Structure

Protons (+) and neutrons (0) are in the nucleus; electrons (-) orbit the nucleus in energy levels.

Newton's First Law of Motion

Inertia - Objects in motion stay in motion unless acted on by an external force.

Newton's Second Law of Motion

Force = Mass × Acceleration - More force leads to more acceleration.

Newton's Third Law of Motion

Action-Reaction - Every action has an equal and opposite reaction.

Speed

Distance / Time.

Velocity

Includes direction (e.g., 30 m/s east).

Acceleration

The rate at which velocity changes.

Kinetic Energy

Energy of motion.

Potential Energy

Stored energy.

Heat Transfer

Includes conduction, convection, and radiation.

Conduction

Direct contact (e.g., metal spoon in hot soup).

Convection

Movement of fluids (e.g., boiling water).

Radiation

Transfer through electromagnetic waves (e.g., the Sun).

Cell Theory

All living things are made of cells; the cell is the basic unit of life; all cells come from preexisting cells.

Prokaryotic Cells

No nucleus, simple (e.g., Bacteria).

Eukaryotic Cells

Have a nucleus and organelles (e.g., Plants, Animals, Fungi, Protists).

Photosynthesis

Equation: CO₂ + H₂O + Sunlight → O₂ + Glucose (C₆H₁₂O₆); takes place in the chloroplasts.

Cellular Respiration

Equation: Glucose + O₂ → CO₂ + H₂O + Energy (ATP); takes place in the mitochondria.

The Carbon Cycle

Includes photosynthesis, respiration, decomposition, and combustion.

Big Bang Theory

Universe started from an explosion ~13.8 billion years ago.

Galaxies

Types include spiral (Milky Way), elliptical, and irregular.

Weather

Short-term atmospheric conditions.

Climate

Long-term weather patterns in an area.

Water Cycle

Evaporation → Condensation → Precipitation → Runoff.

Periodic Table of Elements

An organized chart of all known elements, arranged by atomic number (number of protons).

Groups

Vertical columns (1-18) that contain elements with similar chemical properties.

Periods

Horizontal rows (1-7) that show trends in atomic structure.

Atomic Number

The unique number of protons in an element, determining its identity.

Atomic Mass

The mass of an element, typically measured in atomic mass units (amu).

Neutrons

Calculated as Atomic mass - Atomic number.

Metals

Elements that are shiny, good conductors of heat and electricity, malleable, and ductile.

Nonmetals

Elements that are dull, brittle, poor conductors, and many are gases at room temperature.

Metalloids

Elements that have properties of both metals and nonmetals and can be semi-conductors.

Alkali Metals

Highly reactive metals in Group 1 with one valence electron that easily forms +1 ions.

Alkaline Earth Metals

Very reactive metals in Group 2 with two valence electrons that form +2 ions.

Transition Metals

Less reactive metals in Groups 3-12 that can form multiple oxidation states.

Halogens

Very reactive nonmetals in Group 17 with seven valence electrons that need one more to form a stable compound.

Noble Gases

Nonreactive gases in Group 18 with a stable electron configuration and full outer shell.

Atomic Size

Increases down a group and decreases across a period.

Reactivity of Metals

More reactive as you move down a group.

Reactivity of Nonmetals

More reactive as you move up a group.

Electronegativity

Increases across a period and decreases down a group.

Valence Electrons

Electrons in the outermost shell of an atom that determine how elements bond.

Ionic Bond

Transfer of electrons between metals and nonmetals.

Covalent Bond

Sharing of electrons between nonmetals.

Metallic Bond

Electrons move freely between metal atoms, allowing conductivity.

Element

A substance that cannot be broken down into simpler substances.

Atomic Number

The number of protons in the nucleus of an atom.

Symbol

A one or two-letter abbreviation for an element.

Atomic Mass

The weighted average mass of an element's isotopes.

Protons

Positively charged particles in an atom's nucleus.

Neutrons

Neutral particles in an atom's nucleus.

Electrons

Negatively charged particles that orbit the nucleus of an atom.

Formula for Finding Neutrons

Neutrons = Atomic Mass - Atomic Number

Hydrogen (H)

A unique nonmetal that is highly reactive.

Gold (Au) and Silver (Ag)

Excellent conductors, valuable for electronics and jewelry.

Uranium (U)

The heaviest naturally occurring element with atomic number 92.

Carbon (C)

The element of life, found in all living things.

Scientific Method

A systematic approach to inquiry: Observation → Question → Hypothesis → Experiment → Data Collection → Conclusion.

Independent Variable

The variable that is changed in an experiment.

Dependent Variable

The variable that is measured in an experiment.

Control

The variable that remains constant in an experiment.

Scientific Theory

A well-tested explanation for a phenomenon (e.g., Cell Theory, Theory of Evolution).

Scientific Law

A statement that describes patterns in nature (e.g., Law of Gravity, Newton's Laws).

States of Matter

The distinct forms that different phases of matter take on: solid, liquid, gas, plasma.

Physical Properties

Characteristics that can be observed without changing the substance (e.g., color, density).

Chemical Properties

Characteristics that describe a substance's ability to change into different substances (e.g., flammability).

Compound

A substance formed when two or more elements are chemically bonded (e.g., H₂O, CO₂).

Mixture

A combination of two or more substances that are not chemically bonded (e.g., salad, air).

Signs of a Chemical Change

Indicators such as color change, gas production, temperature change, and precipitate formation.

Law of Conservation of Mass

Mass is not created or destroyed in a chemical reaction.

Forms of Energy

Different types of energy including kinetic, potential, thermal, chemical, electrical, and nuclear.

Newton's 1st Law of Motion

An object in motion stays in motion unless acted upon by an external force (inertia).

Newton's 2nd Law of Motion

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F = ma).

Newton's 3rd Law of Motion

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

Law of Conservation of Energy

Energy cannot be created or destroyed, only transferred.

Layers of Earth

The Earth consists of the Crust (solid), Mantle (semi-solid), Outer Core (liquid iron/nickel), and Inner Core (solid iron/nickel).

Plate Tectonics

The theory explaining the movement of the Earth's plates, including convergent, divergent, and transform boundaries.

Water Cycle

The continuous process of evaporation, condensation, precipitation, and collection.

Weather vs. Climate

Weather refers to short-term atmospheric conditions, while climate refers to long-term weather patterns.

Solar System

The collection of planets and other celestial bodies orbiting the Sun.

Moon Phases

The progression of the Moon's appearance from New Moon to Waning Crescent.

Tides

The rise and fall of sea levels caused by the Moon's gravity.

Seasons

The four divisions of the year caused by the tilt of the Earth on its axis.

Cell Theory

The theory that all living things are made of cells, cells are the basic unit of life, and cells come from preexisting cells.

Photosynthesis

The process by which plants convert CO₂ and H₂O into O₂ and glucose using sunlight.