Download 8th Grade 100 Facts Matter 1. Atoms are the basic building blocks of

 8th Grade 100 Facts Matter 1. Atoms are the basic building blocks of matter and are the smallest unit of an element . 2. There are three basic particles in the atom proton , neutron, and electron . 3. A compound is composed of two or more elements chemically combined. 4. Elements are pure substances that cannot be simplified and made up of one kind of atom . 5. Mixtures can be separated by physical means such as filtration , sifting, or evaporation . 6. H eterogeneous mixtures are not uniform and substances can be visibly distinguished. 7. Homogeneous mixture are uniform and substances cannot be visibly distinguished. 8. The atoms or molecules of a solid form a pattern that only allows the atoms to vibrate . 9. In a gas the atoms or molecules move about freely and collide randomly. 10. An atom’s identity is directly related to the number of protons and can be used to predict the chemical reactivity . Periodic Table 11. The alkali metals in group one are the most reactive metals. 12. The halogens in group seventeen are the most reactive nonmentals. 13. The noble gases in group eighteen are the least reactive elements. 14. Metals lose electrons and nonmetals gain electrons. 15. Physical Changes don’t change the chemical composition such as size, shape and phase. 16. As long as the substance is boiling the temperature of the liquid remains constant. 17. Density is a constant property that describes the relationship between mass and volume.
18. Chemical properties describe how a substance is going to react with other substances such as oxygen and acids. 19. A chemical change results in the formation of a new substance such as a precipitate or gas. 20. Reactions occur at different rates, based on concentration, temperature, surface area and the presence of a catalyst . 21. Acids have a pH of less than 7 and bases have a pH of more than 7. 22. The Law of conservation of matter states the number of atoms and mass stays the same no matter how they are arranged. Resources 23. Renewable resources are replaced through natural processes at a rate that is equal to or greater than the rate at which they are being used. 24. Nonrenewable resources are exhaustible because they are being extracted and used faster rate than they are formed. Hydrosphere 25. Salinity in ocean waters is increased by evaporation or by freezing of sea ice and decreased as a result of rainfall, runoff , or the melting of ice. 26. Air temperatures all over the world are regulated by the circulation of heat by the oceans. 27. The water cycle is the continuous movement of water in and around the Earth and is driven by the sun. 28. A river basin is the portion of land that drains into a river and its tributaries. 29. Estuaries are areas where fresh and salt water mix, producing variations in salinity and high biological activity. 30. Upwelling happens when warm surface water near coastal areas is blown offshore by winds causing cooler nutrient rich water to rise. 31. Cold water with low salinity and high pressure hold the most amounts of ocean gases. 32. Dissolved carbon dioxide in oceans form bicarbonate that is used to make shells. 33. Physical variables that affect the health of a water system are temperature , turbidity and water movement. 34. Chemical variables that affect the health of a water system are dissolved oxygen and other gases, pH , salinity and nitrates. Ecosystems 35. Ecosystems include both biotic and abiotic factors. 36. A group of the same organisms that can interbreed are called species . 37. A population is a group of organisms belonging to the same species that live in a particular area. 38. Different populations make up communities . 39. Biodiversity describes the variety of species found in Earth’s ecosystems . 40. Population density measures the number of individual organisms living in a defined space. 41. Predation is an interaction between species in which one species (the predator ) eats the other (the prey ). 42. Competition is a relationship that occurs when two or more organisms need the same resource at the same time. 43. An ecological niche refers to the role of an organism in its environment including type of food it eats, how it obtains its food, and how it interacts with other organisms. 44. Symbiosis exists between organisms of two different species that live together in direct contact. 45. Parasitism is a symbiotic relationship in which one organism benefits at the expense of another organism. 46. Mutualism is a symbiotic relationship in which both organisms benefit. 47. Food provides molecules that serve as fuel and building material for all organisms. 48. Producers use the energy in light to make glucose from carbon dioxide and water through the process of photosynthesis , which also releases oxygen. 49. Consumers obtain food from eating plants or eating other animals. 50. During aerobic cell respiration , oxygen reacts with glucose to provide energy and produce carbon dioxide waste. 51. Decomposers recycle nutrients from dead plant or animal matter back to the soil 52. Primary consumers that eat green plants are called herbivores . 53.Consumers that only eat other consumers are called carnivores . 54. Consumers that eat both plants and animals are called omnivores . 55. Another term for producer is an autotroph while another term for consumer is a heterotroph . 56. In a food chain, only 10% of the energy is transferred to the next organism. Structures and Functions of Living Organisms
57. Microbiology explores microscopic organisms including viruses, bacteria, protists, and some fungi. 58. Viruses are non­living particles composed of either DNA or RNA and needs a host cell to reproduce. 59. Eukaryotic cells are complex and contain membrane bound organelles (ex: plant and animal). 60. Prokaryotic cells are simple, unicellular, and do not contain membrane bound organelles (ex: bacteria). 61. Bacteria reproduce through binary fission , a form of asexual reproduction. 62. Asexual reproduction involves 1 parent and offspring that is genetically identical to the parent. 63. Antibiotic resistance in bacteria occurs when mutated bacteria survive exposure to an antibiotic and form a new resistant population of bacteria. 64. Fungi are eukaryotic decomposers. 65. Mold spores can become airborne, be inhaled, and trigger an allergic reaction in some people. 66.A parasite is an organism that feeds on another, called the host . 67.A pandemic is an outbreak of a disease that is widespread, usually worldwide, while an epidemic is confined to a particular region.
68. Biotechnology is the use of living organisms to solve problems and make useful products, such as food and medicines.
Molecular Biology 69. Food provides molecules that serve as fuel and building material for all organisms. 70. Cells carry on the many functions needed to sustain life. 71. Through the process of cellular respiration , cells convert energy (glucose) to a usable form of energy (ATP). 72. Matter moves within organisms through a series of chemical reactions in which food is broken down and rearranged to form new molecules. 73. A balanced diet combined with regular exercise aid in the overall general health of the body. 74. Metabolism is the set of chemical reactions involved in storing fuel (food) molecules and converting fuel (food) molecules into energy. Evolution and Genetics 75. Change in a species over time is called evolution . 76. Species acquire adaptations, which leads to variations in populations. 77. Comparing fossils can be used as evidence for evolution. 78. Classification allows scientists to examine the relationships between organisms and construct evolutionary trees. 79.Living things evolve in response to changes in their environment . 80. The theory of natural selection states that organisms with beneficial variations will survive to pass on their traits to the next generation. 81. In every population, variation exists within the inherited traits of the individuals. 82. Changes in environmental conditions can affect the survival of individual organisms and entire species. 83. The greater the diversity within a species, the greater the chances are for that species to survive during environmental changes. Earth’s History
84. Fossils found in sedimentary rocks are preserved remains or traces of organisms that provide evidence of how life and the environment have changed. 85. Mold fossils forms when sediments bury an organism and the sediments change into rock leaving the shape of the organism. 86. Cast fossil forms when a mold is filled with sand or mud that hardens into the shape of the organism. 87. Petrified fossil forms when minerals soak into the buried remains, replacing the remains, and changing them into rock. 88. Preserved fossil forms when entire organisms or parts of organisms are prevented from decaying by being trapped in rock, ice, tar,or amber. 89. Carbonized fossil forms when organisms or parts are pressed between layers of soft mud or clay that hardens squeezing almost all the decaying organism away leaving the carbon imprint in the rock. 90. Trace fossil forms when the mud or sand hardens to stone where a footprint, trail, or burrow of an organism was left behind. 91. The four Era’s of Earth’s history in order are precambrian , paleozoic, mesozoic and cenozoic . 92. Humans first appeared in the cenozoic era. 93. The mass extinction that ended the paleozoic era caused most marine invertebrates as well as amphibians to disappear. 94. Reptiles, dinosaurs small mammals, birds and flowering plants appeared in the mesozoic era. 95.The law of superposition states that each rock layer is older than the one above it. 96. Index fossils are organisms that existed for short period of time that can be used to date rocks. 97. Carbon­14 dating is an example of absolute dating in which radioactive parent atoms decay into more stable daughter atoms. 98. Ice cores contain layers of ice that record the atmospheric composition at the time it was formed.
99. In a dip slip fault, two pieces of land change their vertical position compared to one another. 100. In a strike slip fault, two pieces of land move horizontally.