Name: 8 th Grade Science STAAR Review Booklet My STAAR Goal:
Table of Contents: Matter and Energy Matter and Energy Vocabulary Page 3-5 Atomic Structure Page 6 Arrangement of the Periodic Table Page 7 Metals, Nonmetals, and Metalloids Page 8 Elements, Compounds, and Mixtures Page 9 Chemical Formulas Page 10 Chemical Equations Page 11 Chemical Reactions Page 12 Calculating Density Page 13 Energy Flow Page 14 Matter and Energy Assessment Page 15-16 2
Matter and Energy Vocabulary Atomic Structure Atom - the basic building block of matter that make up everyday objects Nucleus - the center of an atom that contains the protons and neutrons Electron Cloud - the area around the nucleus of an atom where electrons are found Protons positive charged subatomic particles found in the nucleus Neutrons neutral charged subatomic particles found in the nucleus Electrons negative charged subatomic particles found in the electron cloud surrounding the nucleus Valence Electrons - the electrons on the outer shell of an atom that are involved in forming bonds Atomic Number - the number of protons or electrons contained in an element Atomic Mass - the number of protons plus the number of neutrons contained in an atom s nucleus Chemical Symbol - a set of characters (letters) that are used to represent an element Bohr Model a diagram that shows an atom s nucleus surrounded by an electron cloud Arrangement of the Periodic Table Periodic Table a table of the chemical elements arranged in order of atomic number Group/Family - the name given to the vertical columns of elements on the Periodic Table Period/Row - the name given to the horizontal rows of elements on the Periodic Table Reactivity the tendency of a substance to react with its surroundings or certain other substances Alkali Metals elements located in group/family 1 on the Periodic Table Alkaline Earth Metals elements located in group/family 2 on the Periodic Table Transition Metals elements located in groups/families 3-12 on the Periodic Table Halogens elements located in group/family 17 on the Periodic Table Noble Gases elements located in group/family 18 on the Periodic Table 3
Matter and Energy Metals, Nonmetals, and Metalloids Metals elements located to the left of the stair-step (zig zag) line on the Periodic Table Nonmetals elements located to the right of the stair-step (zig zag) line on the Periodic Table Metalloids elements located on the stair-step (zig zag) line on the Periodic Table except for Aluminum Luster the way light reflects from the surface of a substance Malleability the ability to be hammered into thin sheets Ductility the ability to be stretched into a wire Brittleness the ability to break or shatter under stress Conductivity the ability to move heat or electricity from one place to another Elements, Compounds, and Mixtures Element - a pure substance that cannot be broken down chemically Compound - a substance that consists of 2 or more elements combined in a set ratio Mixture - two or more substances that are together, but not chemically combined Organic Compounds - compounds containing carbon that are typically found in living systems Chemical Formulas Molecule - two or more atoms joined together chemically Subscript - the number written after an element s symbol in a chemical formula that indicates the number of atoms of a specific element Coefficient the number in front of an element or compound that indicates the number of molecules in a chemical formula Chemical Equations Reactants elements or compounds on the left side of a chemical equation Products elements or compounds on the right side of a chemical equation Balanced Equation - the number of atoms for each element are equal for the reactants and products Unbalanced Equation - the number of atoms for each element are not equal for the reactants and products Law of Conservation of Mass - matter cannot be created or destroyed 4
Matter and Energy Chemical Reactions Chemical Change - the type of change that results in the formation of new chemical substances Physical Change - the type of change in which the form of matter is altered, but one substance is not transformed into another Chemical Property - a characteristic that can only be determined by changing the identity of a substance Physical Property - a characteristic that can be observed or measured without changing the composition of a substance Evidence of a Chemical Reaction a chemical reaction has occurred if any of the following take place: unexpected temperature change, unexpected color change, production of gas, change in odor, or formation of a precipitate Calculating Density Mass the amount of matter in an object Volume the amount of space taken up by an object Density the ratio of an object s mass to its volume Regular Shaped Object an object that has a measurable length, width, and height (ex. rectangular prism, cube, tissue box) Irregular Shaped Object an objet that does not have a measurable length, width, or height (ex. marble, rock, key) Triple Beam Balance a piece of lab equipment that measures the mass of an object Graduated Cylinder a piece of lab equipment that measures the volume of an object Water Displacement Method a method that involves putting an object into water and carefully recording how much the water level rises Energy Flow Food Chain - a series of events in which one organism eats another in order to gain energy Food Web a diagram that shows many overlapping food chains Energy Pyramid - a diagram that shows the amount of energy moving from one feeding level to another 5
Atomic Structure Parts of an Atom Protons positive charged subatomic particles found in the nucleus; determine the identity of an element Neutrons neutral charged subatomic particles found in the nucleus Electrons negative charged subatomic particles found in the electron cloud surrounding the nucleus Protons Neutrons Electrons APE MAN Strategy (neutral atom) Atomic Number = Protons = Electrons Mass Number Atomic Number = Neutrons Mass, Charge, and Location 6 C Carbon 12.011 Atomic Number = 6 Protons = 6 Electrons = 6 Mass Number (rounded) = 12 Atomic Number = 6 Neutrons = 12 6 = 6 Subatomic Particle Mass Charge Location Proton 1 amu Positive (+) Nucleus Neutron 1 amu Neutral (0) Nucleus Electron 1/1837 amu (tiny!) Negative (-) Electron Cloud Bohr Model 6 C Carbon 12.011 Bohr Model of Carbon Carbon contains 6 total electrons, but only 4 valence electrons. Valence electrons are the electrons on the outermost shell that are involved in forming bonds. 6 Periodic Table cell for Carbon
P E R I O D S Arrangement of the Periodic Table GROUPS/FAMILIES 1-18 Group/Family Number the number of valence electrons for certain elements can be determined from the group number (Groups 1, 2, 13-18). Ex. Hydrogen (H) belongs to Group 1, so it contains 1 valence electron. Boron (B) belongs to group 13, so it contains 3 valence electrons. If the group number is two digits, you only need to look at the 2 nd digit to determine the valence number. Groups/Families are the vertical columns on the Periodic Table There are 18 Groups/Families Elements in the same Group/Family have similar properties Group 1 = Alkali Metals; Group 2 = Alkaline Earth Metals; Groups 3-12 = Transition Metals; Group 17 = Halogens; Group 18 = Noble Gases Period Number the number of energy levels/shells can be determined from the period number. Ex. Calcium (Ca) belongs to Period 4, so it contains 4 energy levels/shells. Periods are the horizontal rows on the Periodic Table There are 7 Periods Proton number increases as you move to the right of each period Reactivity of metals generally decreases as you move to the right of each period Want to hear a joke about Sodium? Na I would tell you a joke about the Periodic Table, but all the good ones Argon. 7
Metals, Nonmetals, and Metalloids Group Nonmetals Metals Properties of Metals, Nonmetals, and Metalloids Metalloids Metals Shiny High melting point Mostly silver or gray in color Mostly solids at room temperature Mercury (Hg) is a liquid at room temperature Malleable able to be hammered into a thin sheet Ductile able to be drawn/pulled into a wire Good conductors of heat and electricity Nonmetals Dull Low melting point Brittle break easily Not malleable Not ductile Poor conductors of heat and electricity Metalloids Found on the zig-zag line on the Periodic Table of Elements Have properties of both metals and nonmetals Can be shiny or dull Semiconductors able to conduct electricity under certain conditions 8
Elements, Compounds, and Mixtures Elements Pure substances Substances that are not able to be broken down chemically Found on the Periodic Table of Elements Hydrogen and Helium are the most common elements in the universe Oxygen and Silicon are the most common elements in Earth s crust Gold (Au) Element Example 1 Element Example 2 Element Example 3 Compounds C 6 H 12 O 6 (Glucose) Pure substances Composed of two or more different elements chemically combined (bonded) Substances that are able to be broken down chemically Contain different properties than the elements that make them up Water, Glucose (sugar), and Carbon Dioxide are three extremely important compounds for life Compound Example 1 Compound Example 2 Compound Example 3 Mixtures Composed of two or more different elements or compounds that are not chemically combined Substances can be separated filtration, evaporation, magnetic effect, etc. Substances do not undergo chemical changes when combined to form a mixture Can be homogeneous (uniform composition) or heterogeneous (no uniform composition) Air, Salt Water, and Steel are three common examples of mixtures Mixture of Elements Mixture of Compounds Mixture of Elements and Compounds Organic Compounds Compounds that contain Carbon and at least one atom of Hydrogen, Oxygen, Phosphorus, Sulfur, or Nitrogen Carbon is the central element to all living organisms Organic molecules include: Carbohydrates, Lipids (fats), Proteins, and Nucleic Acids (DNA and RNA) 9
Chemical Formulas Determining Atoms, Elements, and Molecules from Chemical Formulas Elements Found on the Periodic Table of Elements Represented by capital letters Contain 1 or 2 letter symbols (first letter is capitalized, second letter is lower case) Atoms Represented by a subscript Located after the symbol of each element Written as a small number Add the atoms of each element in the formula to determine the total number of atoms If there is no subscript after an element s symbol, then there is just 1 atom of that specific element Molecules Represented by a coefficient Located at the beginning of a chemical formula Written as a large number Must multiply the number of atoms by the coefficient to determine the total number of atoms If there is no coefficient at the beginning of a specific formula, then there is just 1 molecule Coefficient 4 CO 2 Subscript 4 molecules of Carbon Dioxide 1 atom of Carbon X 4 molecules = 4 total atoms of Carbon 2 atoms of Oxygen X 4 molecules = 8 total atoms of Oxygen Determine the Molecules, Elements, and Atoms for the Chemical Formulas below. Chemical Formula Number of Molecules Number of Elements Number of Atoms C 6 H 12 O 6 1 3 24 2H 2 O 2 2 6 3Fe 2 O 3 3 2 15 4NH 3 2C 2 H 4 O 2 10
Chemical Equations Parts of a Chemical Equation Reactants Located on the left side of the equation Elements or compounds that are present before a reaction takes place Products Located on the right side of the equation Elements or compounds that are present after a reaction takes place (new substances) RAP Strategy Reactants Arrow Products 6H 2 O + 6CO 2 C 6 H 12 O 6 + 6O 2 Balanced and Unbalanced Chemical Equations Find the number of atoms of each element on the reactant side Find the number of atoms of each element on the product side If the number of atoms of each element are the same on the reactant and product side then the equation is balanced If the number of atoms of each element are NOT the same then the equation is unbalanced 2Ag + H 2 S Ag 2 S + H 2 Element Reactant Product Ag 2 2 H 2 2 S 1 1 BALANCED Zn + HCl ZnCl 2 + H 2 Element Reactant Product Zn 1 1 H 1 2 Cl 1 2 Law of Conservation of Mass Matter cannot be created or destroyed The mass on the reactant side must equal the mass on the product side If you begin with 100 grams of substances, you must end with the same amount UNBALANCED CaO + CO 2 CaCO 3 40 g + 60 g = 100 g 11
Chemical Reactions Evidence of a Chemical Reaction Unexpected Change in Temperature Energy is absorbed in a reaction causing the temperature of a substance to decrease (endothermic) Energy is released in a reaction causing the temperature of a substance to increase (exothermic) Unexpected Change in Color Color change occurs when mixing or combining substances Example: Mixing 2 clear liquids and the solution turns pink (unexpected) Non-example: Mixing red food coloring into water and the solution turns red (expected) Production of Gas Gas, bubbling, or fizzing occurs when mixing or combining substances Example: Mixing vinegar and baking soda (carbon dioxide gas is released) Non-example: Bubbles from boiling water (physical change due to evaporation) Production of Precipitate Solid substance formed from a liquid solution Change in Odor An odd or different odor produced from a substance Example: A rotting egg or piece of meat; spoiled milk or sour cream Non-example: Air freshener sprayed into a room Physical and Chemical Changes in Digestion Physical Changes in Digestion Mouth teeth break food down into smaller pieces Esophagus squeezes food down into stomach Stomach churns food Small Intestine squeezes waste into large intestine Large Intestine squeezes waste into rectum Chemical Changes in Digestion Mouth saliva chemically breaks down food Stomach enzymes and acid mix together to further break down food for absorption Small Intestine nutrients absorbed into bloodstream Large Intestine water absorbed from waste Rectum/Anus changes shape as waste exits the body 12
Calculating Density Density can be determined by dividing the mass of an object by its volume. Density = Mass Volume Density of a Regular Shaped Object Mass can be determined using a triple beam balance or an electronic scale Volume can be determined by measuring and multiplying the length, width, and height (Length X Width X Height) Triple Beam Balance Length X Width X Height Density = 142 grams 16 cm 3 2 cm Density = 8.875 g/cm 3 Mass = 142 grams 2 cm Volume = 16 cm 3 Density of an Irregular Shaped Object Mass can be determined using a triple beam balance or an electronic scale Volume can be determined using water displacement with a graduated cylinder Triple Beam Balance Graduated Cylinder Density = 72 grams 5 ml Density = 14.4 g/ml Mass = 72 grams Before: 5 ml After: 10 ml Volume = 10 ml 5 ml = 5mL Density of Water The density of water is 1 g/ml An object with a density greater than 1 g/ml will sink when placed into water An object with a density less than 1 g/ml will float when placed into water Vegetable Oil = 0.92 g/ml Water = 1.0 g/ml Corn Syrup = 1.37 g/ml 13
Energy Flow Energy Flow in Living Systems Food Chains Shows the path of energy from organism to organism Energy begins with the Sun Energy is obtained by producers from the Sun through the process of photosynthesis The arrows show the direction of energy flow Food Webs Many overlapping food chains linked together More realistic diagram of the relationships that occur within an ecosystem A predator from one food chain may be linked to the prey of another food chain Energy Pyramids Shows the amount of energy moving from one feeding level to another Producers are located at the bottom; top-level consumers are located at the top The amount of energy available decreases as you move up the pyramid Owls Mice Grass 14
Matter and Energy Assessment Use a Periodic Table to answer questions 1-17. Element Symbol Protons Electrons Neutrons 1. Lithium 2. Oxygen 3. Chlorine 4. 5. 6. 7. What element is found in Group 16 and Period 3? 8. What element is found in Group 14 and Period 2? 9. What element is found in Group 2 and Period 4? 10. Potassium 11. Argon 12. Nitrogen Element Number of Valence Electrons Number of Energy Levels Use the characteristics on the chart below to determine if the substance is a Metal, Nonmetal, or Metalloid. Then, list 2 examples of elements that would belong to each specific category. Characteristics Metal/Nonmetal/Metalloid 2 Examples 13. Dull, Brittle, Poor Conductor 14. Semiconductor, Ductile 15. Shiny, Malleable, High Melting Point 16. Is Hydrogen (H) classified as a Metal, Nonmetal, or Metalloid? 17. Is Aluminum (Al) classified as a Metal, Nonmetal, or Metalloid? 15
Determine if the following are examples of Elements, Compounds, or Mixtures. 18. Salt Water 21. Na 24. Iron 27. Cement 19. CO 2 22. Air 25. Chex Mix 28. H 2 20. Gold 23. C 6 H 12 O 6 26. HCl 29. NaOH For questions 30-35, list the 6 elements that are most commonly found in Organic molecules. 30. 31. 32. 33. 34. 35. Identify the number of Molecules, Elements, and Total Atoms for questions 36-38. Chemical Formula Molecules Elements Total Atoms 36. 4CO 2 37. 2NaOH 38. 3Fe(OH) 3 Determine if the following equations are Balanced or Unbalanced. 39. 4FeS + 7O 2 2Fe 2 O 3 + 4SO 2 40. 2C 2 H 6 O + 3O 2 2CO 2 + 3H 2 O Calculate the missing mass for the following chemical equations. 41. 4Al + 3O 2 2Al 2 O 3 42. 2H 2 + O 2 2H 2 O 13g + 67g 18.5g + 6.5g 43. Describe the physical and chemical changes that occur in digestion when eating a slice of pizza in the box below. 44. Describe the evidence of a chemical change when burning a piece of paper in the box below. Calculate the Density of the substances below to determine if they will float or sink in water. 45. Substance 1 450 grams 90 ml 46. Substance 2 35 grams 70 ml 47. Substance 3 24 grams 12 ml Mass Volume Density Float or Sink Draw your own Food Chain, Food Web, or Energy Pyramid below. Then, describe the flow of energy that occurs from one feeding level to the next. Drawing Description of Energy Flow 16