Download Eighth Grade Science Essential Knowledge 1. Matter – anything that

Eighth Grade Science Essential Knowledge
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Matter – anything that has mass and volume. Matter exists usually as a sold, liquid or gas
Mass – a measure of how much matter an object is made of
Space – the unlimited 3 dimensional realm in which all material objects and all events occur
Law of Conservation of Mass – a law stating that atoms are not created nor destroyed in a chemical reaction
Mixture – a combination of 2 or more substances that do not combine chemically but remain the same
individual substances. Mixtures can be separated by physical means
Element – a substance that cannot be broken down into a simpler substance by ordinary chemical changes. An
element consists of atoms of only one type
Compound – a substance made up of 2 or more different types of atoms bonded together
Atom – Smallest particle of an element that has the chemical properties of that element
Molecule – a group of atoms held together by covalent bonds so that they move as a single unit
Solid – matter that has a definite shape and a definite volume. The molecules in a solid are in fixed positions
and are close together
Liquid – matter that has a definite volume but does not have a definite shape. The molecules in a liquid are
close together but not bound to one another
Gas – matter with no definite volume and no definite shape. The molecules in a gas are very far apart, and the
amount of space between them can change easily
Density – a property of matter representing the mass per unit volume
Volume – an amount of three-dimensional space, often used to describe the space that an object takes up
Fluid - a substance that can flow easily, such as a gas or a liquid
Melting point – the temperature at which a substance changes from its solid state to its liquid state through
melting
Boiling point – the temperature at which a substance changes from its liquid state to its gas state through boiling
Freezing point – the temperature at which a substance changes from its liquid state to its solid state through
freezing
Solubility – the amount of solute that dissolves in a certain amount of a solvent at a given temperature and
pressure to produce a saturated solution
Solute – in a solution a substance that is dissolved in a solvent
Solvent – in a solution the substance that dissolves a solute and makes up the largest percentage of a solution
Chemical change – a change of one substance into another substance
Physical Change – a change in a substance that does not change the substance into a different one
Chemical property – characteristics that describe how a substance interacts with other substances to produce a
different kind of matter
Physical property – characteristics of a substance that can be observed without changing the identity of the
substance
Mechanical energy – a combination of the kinetic energy and potential energy an object has
Thermal energy – the energy an object has due to the motion of its particles; the total amount of kinetic energy
of particles in an object
Kinetic energy - the energy of motion. A moving object has the most kinetic energy at the point where it moves
the fastest
Combustion – the act or process of burning
Friction – a force that resists the motion between 2 surfaces in contact
Electric motors – a device that converts electrical energy to mechanical torque
Generator – a device that converts kinetic energy into electrical energy. Generators produce electric current by
rotating a magnet within a coil or wire within a magnetic field
33. Electrical energy – energy made available by the flow of electrical charge through a conductor
34. Respiration – the exothermic process by which living things release energy from glucose and oxygen and
produce carbon dioxide and water
35. Photosynthesis - in green plants the endothermic process in which light is absorbed and used to change carbon
dioxide and water into glucose and oxygen
36. Temperature – a measure of the average amount of kinetic energy of the particles in an object
37. Conduction – the process by which energy is transferred from a warmer object to a cooler object by means of
physical contact
38. Convection – a process by which energy is transferred in gases and liquids, occurring when a warmer, less dense
area of gas or liquid is pushed up by a cooler, more dense area of the gas or liquid
39. Radiation – energy that travels across distances in the form of electromagnetic waves
40. White light – light that contains all the wavelengths of visible light
41. Prism – an optical tool that uses refraction to separate wavelengths that make up white light
42. Light colors – reflect sunlight, reflecting heat
43. Dark colors – absorbs heat from light
44. Wave – a disturbance that transfers energy from one place to another without requiring matter to move the
entire distance
45. Wavelength – the distance from one wave crest to the next crest; the distance form any part of one wave to the
identical part of the next wave
46. Frequency – the number of waves that pass a fixed point in a given amount of time, usually 1 second; the
number of cycles per unit of time
47. Speed – a measure of how fast something moves through a particular distance over a definite time period;
speed is distance divided by time
48. Wave motion – a disturbance that travels through space and time, usually accompanied by a transfer of energy
49. Sound waves – a type of wave that is produced by a vibrating object and that travels through matter
50. Light waves – electromagnetic waves that we can see as the colors of the rainbow, each color has a different
wave length
51. Medium – a substance through which a wave moves
52. Motion – a change in position over time
53. Frame of reference(point of reference) – an indicator that orients you
54. Position – an object’s location
55. Acceleration – the rate at which velocity changes over time
56. Velocity – a speed in a specific direction
57. Force – a push or a pull; something that changes the motion of an object
58. Balanced force – opposing forces that are equally pushing or pulling against each other
59. Unbalanced force - forces that produce a change in an object’s motion
60. Currents – steady motion in one direction
61. Electric current – a continuous flow of electric charge, which is measured in amperes
62. Cell – smallest unit of an organism that can carry on life functions
63. Organism – any living thing
64. Multi-cell organism – cells that work and function together to create a living organism, as in plants and animals
65. Single-cell organism – made up of only one cell as in bacteria
66. Parts of plant cell – cell membrane, vacuole, nucleus, chloroplasts, cell wall, cytoplasm
67. Cell wall – rigid structure that encloses, supports, and protects the cells of plants, algae, fungi and most bacteria
68. Vacuole – a small cavity in cytoplasm of a cell, bound by a membrane, containing water, food or waste
69. Chloroplast – green, chlorophyll-containing, plant cell organelle that uses light energy to produce sugar from
carbon dioxide and water
70. Chlorophyll – green, light-trapping pigment in plant chloroplasts that is important in photosynthesis
71. Mitosis – cell process in which the nucleus divides to form 2 nuclei identical to each other and identical to the
original nucleus, in a series of steps(prophase, metaphase, anaphase, telophase)
72. Respiration – process by which producers and consumers release stored energy from food molecules, series of
chemical reactions used to release energy stores in food molecules
73. Glucose – a type of sugar the body uses for energy
74. Nerve cell – a specialized cell that conducts nerve impulses, spinal cord for example
75. Muscle cell – an elongates contractile cell that forms the muscles of the body
76. Skin cell – any of the cells making up the skin
77. Bone cell – a cell found in bone
78. Blood cell – cells that circulate in the blood as white blood cells or red blood cells
79. Tissue – group of similar cells that work together to do one job
80. Organ – structure, such as the heart, made up of different types of tissue that all work together
81. Organ system – a group of organs that work together to perform a certain task
82. Muscle – organ that can relax, contract, and provide the force to move bones and body parts
83. Cardiac muscle – striated, involuntary muscle found only in the heart
84. Striated muscle – the muscle involved with moving skeletal parts to which it is usually attached
85. Smooth muscle – muscles involving involuntary movement, as in the intestines, blood vessels
86. Digestive system – helps convert food into usable nutrients
87. Respiratory system – supplies the blood with oxygen in order to deliver oxygen to all parts of the body
88. Circulatory system – a body-wide network of blood, blood vessels and lymph, empowered by the heart
89. Excretory system - removes metabolic waste and maintains the proper amount of water in the body
90. Skeletal system – framework of the body which protects and supports it with bones
91. Nervous system – made up of the brain, spinal cord and nerves that serve as the processing center to control the
body
92. Environment – conditions and surrounding that influence development and behavior
93. Adaptation – any variation that makes an organism better suited to its environment
94. Ectotherm – vertebrate animal whose internal temperature changes when the temperature of its environment
changes, cold-blooded
95. Endotherm – vertebrate animal with a nearly constant internal temperature, warm blooded
96. Behavioral responses – the way in which an organism interacts with other organisms and its environment; can be
innate or learned
97. Dichotomous key – a key for the identification of organisms based on a series of choices between alternative
characteristics
98. Kingdom – first and largest category used to classify organisms
99. Protist – one or many-celled eukaryotic organism that can be plantlike, animal-like, or funguslike
100. Producers – organism, such as a green plant or alga, that uses an outside source of energy like the Sun to create
energy-rich food molecules
101. Consumers – organism that cannot create energy-rich molecules but obtains its food by eating other organisms
102. Pollutant – substance that contaminates any part of the environment
103. Deforestation – the clearing of trees
104. Population - all organisms that belong to the same species living in a community
105. Ecosystem – community of organisms and the environment they inhabit
106. Biotic – features of the environment that are alive or were once alive
107. Abiotic – nonliving, physical features of the environment, including air, water, sunlight, soil, temperature, and
climate
108. Physical factors that affect ecosystems
109. Genetic s – the study of how traits are inherited through the action of alleles
110. Gregor Mendel – the founder of the science of genetics
111. Inherited traits – characteristics of a parent being passed on to its offspring through heredity
112. Gene – section of DNA on s chromosome that contains instructions for making specific proteins
113. Chromosome – structure in a cell’s nucleus that contains hereditary material
114. Trait – a distinguishing characteristic or quality
115. Gamete – a reproductive cell that unites with another cell to form a new organism
116. Dominant genes – describes a trait the covers over, or dominates, another form of that trait
117. Recessive genes – describes a trait that is covered over, or dominated, by another form of that trait and seems
to disappear
118. Punnett square – a tool to predict the probability of certain traits in offspring that shows the different ways that
alleles can combine
119. Extinction – no longer in existence; has died out
120. Survival of the fittest – the survival of those best adapted to the environmental conditions
121. Genetic diversity – advantage to sexual reproduction
122. Asexual reproduction – a type of reproduction – fission, budding and regeneration – in which a new organism is
produced from one organism and has DNA identical to the parent organism
123. Evolution – change of living things over time
124. Fossil – trace or remains of a plant or an animal in sedimentary rock
125. Biological adaptation – the adjustment of an organism to its environment
126. Natural selection – parts of Earth’s environment that supply materials useful or necessary for the survival of
living organisms
127. Biological evolution – change in inherited traits over time
128. Diversity of species 129. Photosynthesis – process by which plants and many other producers use light energy to produce a simple sugar
from carbon dioxide and water and give off oxygen
130. Food web – model that shows the complex feeding relationships among organisms in a community
131. Food chain – the chain from a food source to the ultimate consumer
132. Closed system- an isolated region where no matter or energy can cross
133. Decomposer – an organism that breaks down the cells of dead plants and animals
134. Disease – an impairment of normal functioning cells
135. Biological agents(microorganism) – have the ability to negatively affect life
136. Bacteria – a very large group of microorganisms; can be harmful or beneficial
137. Virus – a strand of hereditary material surrounded by a protein coating that can infect and multiply in a host cell
138. Environmental factors – factors that affect or influence any living organism
139. Genetic – The study of how traits are inherited through the actions of alleles
140. Genetic disorders – a disease that is caused by an abnormality in DNA
141. Reproductive system – the system of organs and parts which function in reproduction
142. Homeostasis – the tendency of a system to maintain internal stability
143. Plate tectonics – theory that the lithosphere is made up of plates that float on the asthenosphere and that the
plates possibly are moved by convection
144. Earthquake – vibration of the earth’s crust
145. Epicenter – point on the earth’s surface directly above the focus of an earthquake
146. Volcano – lava and pyroclastic material built up on the earth’s surface around a vent
147. Seafloor spreading – movement of the ocean floor away from either side of a mid-ocean ridge
148. Mountain - a natural elevation of the earth’s surface greater than 2000 feet or 610 meters
149. Landforms – physical feature of the earth’s surface
150. Weathering – change in the physical form or chemical composition of rock materials exposed at the earth’s
surface
151. Physical weathering – breakdown of rocks and soils through direct contact with atmospheric conditions, such as
heat, water, ice, pressure
152. Chemical weathering – breakdown of rocks, soil and minerals through direct contact with atmospheric chemicals
153. Erosion – process by which the products of weathering are transported
154. Sediment – fragments that result from the breaking of rocks, minerals, and organic matter
155. Landslide – sudden movement of loose rock and soil down a slope
156. Rock cycle – series of processes in which rock changes from one type to another and back again
157. Igneous rocks – rock formed from cooled and hardened magma
158. Metamorphic rock – rock formed from other rocks as a result of intense heat, pressure, or chemical process
159. Sedimentary rock – rock formed from hardened deposits of sediment
160. Relative age – age of an object compared with the ages of other objects
161. Rock strata – distinct layers in rock
162. Law of superposition – principle that a sedimentary rock layer is older than the layers above it and younger than
the layers below it
163. Index fossils – guide fossil; fossil found in the rock layers of only one geological age and is used to establish the
absolute age of the rock layers
164. Alpine Glaciers – form on the crest and slopes of mountain
165. Continental Glacier – a broad sheet of ice resting on a plain and spreading outward
166. Hardness – resistance to fracture, chip, bend or break
167. Cleavage – splitting of mineral along smooth, flat surfaces
168. Streak – the color a rock or mineral takes on when scratched on a surface
169. Luster – a shine by reflecting light, a sparkle
170. Ozone – form of atmospheric oxygen that has 3 atoms per molecule
171. Ozone depletion – a decline on the total volume of the ozone layer in the atmosphere
172. Heat transfer – 3 types of heat for the Earth
173. Conduction – type of energy transfer in which vibrating molecules pass heat along to other vibrating molecules
by direct contact
174. Convection – transfer of eat through the movement of heated material
175. Radiation – the emission or transfer of radiant energy as particles or waves
176. Air current – air moving from an area of high pressure to an area of low pressure
177. Coriolis effect – deflection of wind and ocean currents caused by the earth’s rotation
178. Weather – general condition of the atmosphere at a particular time and place
179. Barometer – instrument that measures atmospheric pressure
180. Barometric pressure – atmospheric pressure
181. Dew point – temperature to which air must be cooled to become saturated
182. Wind - air in natural motion
183. Temperature – measure of motion
184. Precipitation – process by which water falls from clouds to the earth as rain, snow, sleet and hail
185. Clouds – a visible collection of particles of water or ice suspended in the air
186. Stratus cloud – cloud with a sheet-like or layered form that is the lowest cloud in the sky
187. Cumulus cloud – thick, billowy cloud that forms above stratus clouds and below cirrus clouds
188. Atmosphere – thick blanket of gases surrounding the earth
189. Stratosphere – layer of the atmosphere that extends upward from the troposphere to an altitude of 50km;
contains most ozone atmospheric ozone
190. Ozone layer – layer of the uppermost atmosphere that protects organisms on earth from ultraviolet radiation
191. Ionosphere – lower region of the thermosphere ,at an altitude of 80 – 550 km
192. Thermosphere – the atmospheric layer above the mesosphere
193. Troposphere – atmospheric layer closest to the earth’s surface where nearly all weather occurs
194. Solar radiation – radiation for the sun
195. Electromagnetic spectrum – complete range of wavelengths of radiation
196. Revolution – movement of a planet around the sun
197. Earth’s axis – imaginary straight line running through the earth from pole to pole
198. Rotation – spinning of a plant on its axis
199. Equinox – the time when day and night are equal length
200. Solstice – 2 times during the year when the sun is the farthest from the equator
201. Light year – distance that light travels in one year, about 9.5 trillion km
202. Big Bang Theory – theory that all matter and energy in the universe was compressed into an extremely small
volume that suddenly, billions of years ago, began expanding in all directions
203. Milky Way – spiral galaxy containing our solar system
204. Galaxy – large-scale group of stars
205. Hydrosphere – all the earth’s water
206. Theory – hypothesis or set of hypotheses supported by the results of experimentation and observation
207. Scientific Law – rule that correctly describes a natural phenomenon
208. Doppler Effect – apparent shift in the wavelength of energy emitted by a source moving away from or toward an
observer
209. Spectroscope – instrument that splits white light into a band of colors
210. Seismic wave – vibration that travels through the earth
211. Crust – outermost zone of the solid earth; 1% mass of the earth, oceanic and continental
212. Mantle – zone of rock 2900 km thick below that earth’s crust, lithosphere and asthenosphere
213. Lithosphere – thin outer shell of the earth consisting of the crust and the rigid upper mantle
214. Asthenosphere – zone of mantle beneath the lithosphere that consists of slowly moving solid rock
215. Core – center of the earth, made of iron, 1/3 of the earth’s mass
216. Plasticity – ability for a solid to flow
217. Magnetosphere – a region of space that is affected by the earth’s magnetic field
218. Time Zone – one of 24 regions of the globe approximately marking an hour of time
219. International Date Line – line running from north to south through the Pacific ocean where the date changes
from one day to the next
220. Parallel – any circle that runs east to west around the earth parallel to the equator
221. Latitude – angular distance north or south of the equator
222. Longitude – angular distance east to west of the prime meridian
223. Meridians(Prime meridian) – semicircle on the earth that runs from pole to pole
224. Geomagnetic poles – point on the earth’s surface above a pole of the earth’s imaginary internal magnet
225. Contour interval – difference in elevation between one contour line and the next
226. Topographic map – map that shows the surface features of the earth
227. Continental drift – hypothesis stating that the continents once formed a single landmass,Pangea, broke up and
drifted to their present locations