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6th Grade Science Semester 2 Exam Review Lab Safety Goggles are always required during experiments using heat, chemicals, and glassware. Lab Tools/Measurement Mass- The amount of matter in an object Volume- The amount of space an object occupies Density- The amount of matter in a given volume Another name for the metric system is SI, for international system of units Metric Ruler- measures length Triple Beam Balance- measures mass Graduated Cylinder- measures volume Spring Scale- measures force Thermometer- measures temperature Tongs & Test Tube Holders- used for holding hot objects Measuring Practice Websites: Triple Beam Balance: http://www.wisc-online.com/Objects/ViewObject.aspx?ID=GCH202 Graduated Cylinder: http://www.wisc-online.com/Objects/ViewObject.aspx?ID=gch302 Finding the volume of an irregular object using water displacement: Measure the volume of the water in a graduated cylinder. Add the object. Measure the volume of the water with the object. Subtract the two measurements. The density of water is 1g/ml. Objects with a density greater than 1g/ml sink, objects with a density less than 1g/ml float. If an object’s mass is greater than it’s volume, the object will always sink. Experimental Design The scientific method steps in order: 1. State the Problem 2. Gather Information (research) 3. Make a Hypothesis 4. Perform an Experiment 5. Record and Analyze Data 6. Make a Conclusion Manipulated Variable (Independent Variable)- The factor that is changed purposely during an experiment. Think “Manipulated is changed by man”. There can be only ONE manipulated variable in an experiment. Responding Variable (Dependent Variable)- The factor that responds to the changes made in the experiment. It is what is measured during the experiment. Controlled Variable- The factors that stay the same in the experiment. There can be many controlled variables. DRY MIX- Stand for “The Dependent/Responding Variable is graphed on the Y axis”. “The Manipulated/Independent Variable is graphed on the X axis”. Elements and Compounds Element- A pure substance made of only one kind of atom. Compound- A substance made of two or more atoms chemically combined in a set ratio. How to know the difference between an element and a compound: Each element on the periodic table is represented with a capital letter (and possibly a lower case letter). For example: Oxygen- O, Iron- Fe, Helium- He. By counting the number of capital letters in a chemical formula, you can determine how many different elements are in a substance. CO2 has two capital letters, so it has two different elements (Carbon and Oxygen), which makes it a compound. Physical Properties of Elements Conductivity- The ability to allow the flow of electricity or heat through an object Malleability- The ability to be hammered or flattened into shape Ductility- The ability to string a substance into a wire Luster- How light reflects off of an object (dull or shiny, metallic or non-metallic) Observe the periodic table above. Notice that the metals are blue and located on the left side of the table. The non-metals are red and located on the right side of the table. The metalloids are yellow and are located on a “zig-zag” line between the metals and nonmetals. Which element on this periodic table is mis-colored? Why do you think this is so? Physical Properties of Metals V/S Nonmetals Metals are mostly solids that have shiny luster. They are malleable, ductile, and easily conduct electricity. Nonmetals are usually liquids and gases. When nonmetals are solids, they are usually brittle (break easily), neither ductile nor malleable, and dull in luster. Nonmetals are not conductors. Metalloids are found between metals and nonmetals on the periodic table because they have properties of both metals and nonmetals, depending on the specific element. Heat Transfer ConDuction- The transfer of heat by direct contact. The “D” stands for direct contact. ConVection- The Transfer of heat through a vapor (liquid, gas). The “V” stand for vapor. Radiation- The transfer of heat through waves/empty space. When is heat energy lost? When heat is removed from a substance. Examples are freezing (liquid to solid), and condensation (gas to liquid). When is heat energy gained? When heat is added to a substance. Examples are melting (solid to liquid), creation of steam/vapor (liquid to gas). Energy Forms of EnergyGeothermal- Renewable, no pollution Solar- Renewable, no pollution Hydropower- Renewable, no pollution Natural Gas- Non-renewable, causes pollution Coal- Non-renewable, causes pollution Petroleum- Non-renewable, causes pollution (also called oil) Conservation of Energy: Energy is never created or destroyed, it just transfers from one substance to another. Examples of energy transfer (energy converted from one form to another): Electrical to Thermal- toaster, hair-dryer Chemical to Mechanical- food in your body giving you energy to move, burning coal to make a turbine move Mechanical to Electrical- wind up/crank radio, a moving turbine making electricity Chemical to Radiant- batteries in a flashlight, burning wood on a campfire Ways to Conserve Energy (not wasting energy): Turn off lights when leaving a room, adjusting the thermostat when leaving your house, replace incandescent light bulbs that give off unwanted heat with fluorescent light bulbs, unplug phone chargers when not in use (they still use energy without the phone attached). Potential Energy- energy that is stored. The greater the height of an object, the more potential energy it has. A ball dropped from the top of the bleachers will fall longer than one dropped the middle of the bleachers. It has the greater potential for speed. Kinetic Energy- energy that is in motion Machines Friction- the force that one object exerts on another when two objects rub against each other; examples include rubbing your hands together to make heat and tires on a road. Inclined planes are machines such as ramps and stairs. They make work easier by reducing the force needed to move an object (you don’t have to push as hard). The object will travel a farther distance when using a ramp because it move up the entire length of the ramp, instead of straight up if you were lifting the object. Earth’s Layers The lithosphere is made of the crust and upper mantle. The tectonic plates that move and shape our land are made of the lithosphere. The asthenosphere is made of the middle mantle. It is semi-solid and moves like syrup. Convection currents are found in this layer. The lithosphere floats on top of the asthenosphere. Plate Tectonics Convergent boundary- located where two plates move towards each other. Subduction zones occur at convergent boundaries. Mountains, trenches, and volcanoes can be found at these boundaries. Divergent boundary- located where two plates move away from each other. Mid-ocean ridges are found along these boundaries. Transform boundary- located where two plates slide past each other in a side to side motion. Earthquakes are found at these boundaries. Review the map to the left. Make sure you know the location of the following plates: North American Plate Indo-Australian Plate Nazca Plate South American Plate Eurasian Plate Antarctic Plate African Plate Pacific Plate Space/Astronomy Galileo Galilei- credited for inventing the telescope, observed the movements of planets to prove the heliocentric theory where all the planets in our solar system orbit around the sun. Sir Isaac Newton proved that the planets stay in orbit/motion due to the forces of inertia and gravity. He lived after Galileo and also believed in the heliocentric system. When planning modern space mission (like the Mars Bound Project), NASA must consider the cost of the mission, the energy needs, mass of the equipment, and purpose of the mission (goals). Planets Facts Rocky/Terrestrial Planets (Inner Planets) in order: Mercury- .3 size of Earth Venus- .9 size of Earth Earth- 1 Earth (12,756km in diameter) Mars- .5 size of Earth Gas Giants (made of Hydrogen and Helium) in order: Jupiter- 11 Earths Saturn- 9 Earths Uranus- 3.6 Earths Neptune- 4 Earths Cells Unicellular- one-celled organisms like bacteria and yeast Multicellular- more than one cell, flowers, mushrooms, insects Heterotroph- must eat or obtain food, humans, mushrooms, jellyfish Autotroph- make their own food using sunlight (photosynthesis), green plants Prokaryote- organisms that do not have a good nucleus, bacteria Eukaryote- organisms that have a good membrane bound nucleus that holds the DNA, animals, oak tree, euglena The Cell Theory: 1. All organisms are made of cells. 2. All cells are produced by other living cells. 3. The cell is the most basic unit of life. Four Kingdoms of Eukaryotes Animal Kingdom- multicellular and heterotrophs Plant Kingdom- multicellular and autotrophs Protist Kingdom- unicellular and can be an autotroph or heterotroph Fungi Kingdom- can be multicellular or unicellular and heterotrophs Ecosystems Population- all the organisms that same type (species) in a certain area, a species of ants Habitat- the place an organism lives gets its needs provided for Community- all the different types of organisms living in a certain area, ants and squirrels live in the same community Biotic factors- all the living things in an ecosystem, trees and birds Abiotic factors- all the non-living things in an ecosystem, rocks and water Rock Cycle Igneous Rock- made from magma (molten rock) that has cooled and hardened. Found around volcanoes. Sedimentary Rock- made from compaction (pressing) and cementation (glue) of sediments. Often found in layers by water and can contain fossils. Metamorphic Rock- made from extreme heat and pressure. These rocks can have bands or stripes in them. • All 3 rock types can be directly changed into each other. Speed Speed is calculated by dividing distance by time (distance goes in the calculator first). If a car travels 180 miles in 3 hours, what is the average speed of the car?