Science 8th Grade Overview

Atoms

Building blocks of matter

Electron

A subatomic particle that has a negative charge.

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom.

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom.

Atomic number

the number of protons in the nucleus of an atom

Atomic mass

Number of protons and neutrons

Net (total) charge

The sum of negative and positive charges.

Covalent bond (connection)

A chemical bond formed when two atoms share electrons

Molecules

Groups of two or more atoms held together by chemical bonds.

Cell

Basic unit of life

Nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction. Also the center of an atom.

Mitosis

A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.

Layers of the Earth

crust, mantle, outer core, inner core

Mantle

The layer of hot, solid material between Earth's crust and core.

Earth's crust

Earth's outermost layer of rock

Inner planets

Mercury, Venus, Earth, Mars

Keiper Belt

A region of the solar system beyond the orbit of Neptune, believed to contain many comets, asteroids, and other small bodies made largely of ice.

Outer planets

Jupiter, Saturn, Uranus, Neptune

Solar system

the collection of eight planets and their moons in orbit around the sun, together with smaller bodies in the form of asteroids, meteoroids, and comets.

Skeletal system

Protects and supports body organs and provides a framework the muscles use to support movement. Made up of bones and joints.

Circulatory system

(aka cardiovascular system) This system works as the transportation highway for the body. It consists of the heart, blood, and blood vessels. It transports substances such as oxygen, carbon dioxide, and nutrients in the body.

Nervous system

The network of nerve cells and fibers that transmits nerve impulses between parts of the body.

Digestive system

Breaks down food into absorbable units that enter the blood for distribution to body cells.

Circuit

A complete, closed path through which electric charges flow.

Light Emitting Diode (LED)

A diode that will produce light when current flows through it.

Resistor

An electrical device that resists the flow of electrical current.

Chemical equation

A way to describe a chemical reaction using chemical formulas and other symbols.

Somatic cells

body cells

Gamete cells

sex cells (egg and sperm)

Cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

Prokaryotic cell

A cell that does not have a nucleus or other membrane-bound organelles.

Eukaryotic cell

A cell that has a nucleus and other membrane-bound organelles

Allele

Different forms of a gene

Vertebrates

Animals that have a backbone are called...

Invertebrates

Animals that don't have a backbone are called...

Heterotroph

An organism that cannot make its own food.

Autotroph

Organisms that make their own food

Magma

Molten rock beneath the earth's surface

Lava

Magma that reaches Earth's surface

Earth's core

The extremely hot and dense center of the earth, which is believed to be composed of iron and nickel.

Water cycle

The continuous process by which water moves from Earth's surface to the atmosphere and back.

Enthalpy

Total energy of a system

Entropy

A measure of disorder or randomness.

Exothermic

Chemical Reaction in which energy is primarily given off in the form of heat

Endothermic

Absorbs heat

Force

A push or a pull

Gravitational force

An attractive force that acts between any two objects

Normal force

the force perpendicular to a surface that prevents an object from falling through the surface

Net (total) force

The combination of all forces acting on an object

Friction

A force that opposes motion between two surfaces that are in contact

Embryo

An organism in the earliest stage of development

Thermodynamics

The study of energy transformations that occur in a collection of matter.

Newton

SI unit of force; how force is measured

SI

International System of Units

Digital

Data expressed as series of the digits 0 and 1.

Analog

Relating to or using signals or information represented by a continuously variable physical quantity such as spatial position, voltage, etc.

Joules

Unit of energy

Allele

Different forms of a gene

Gene

A segment of DNA on a chromosome that codes for a specific trait

Chromosomes

Threadlike structures made of DNA molecules that contain the genes

Mass

the amount of matter in an object

Wave

A disturbance that transfers energy from place to place

Wavelength

Horizontal distance between the crests or between the troughs of two adjacent waves

Frequency

the number of complete wavelengths that pass a point in a given time

Amplitude

Height of a wave

Chemical equation

A short, easy way to show a chemical reaction, using symbols.

Kinetic energy

energy of MOTION

Potential energy

Energy that is stored and held in readiness; NOT MOVING

Evaporation

The change of state from a liquid to a gas

Condensation

The change of state from a gas to a liquid

Precipitation

Any form of water that falls from clouds and reaches Earth's surface.

Geology

Study of the earth

Plate tectonics

A theory stating that the earth's surface is broken into plates that move.

Punnett Square

A chart that shows all the possible combinations of alleles that can result from a genetic cross

Deforestation

The removal of trees faster than forests can replace themselves.

Food chain

A series of steps in which organisms transfer energy by eating and being eaten

Gravity

A force that pulls objects toward each other

Tectonic Plates

Sections of the Earth's crust that move due to convection currents.