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8 Grade Physical Science

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8 Grade Physical Science Everything you need to know about: th 8 Grade Physical Science Directions: Answer ALL the questions for each unit, in preparation for the SOL! Each answer must be handwritten, answered completely on your own paper, grouped by unit, and numbered. DON’T define the key terms. This is a summative grade out of 40 points! Unit 1 – Measurement & Safety Key terms: physical science, Newton (N), volume, density, meniscus, cubic centimeter (cm3), liter, water displacement method, weight, metric conversion 1. List five safety procedures for the lab. * Wear safety goggles, apron, gloves, closed-toed shoes, etc. * Waft, never smell directly * Always add acids to water or other chemicals * No food, drink, gum, or tasting of materials in the lab * Tell a teacher if glass or other equipment breaks 2. Why do we use the metric system in science? It is the internationally accepted system of measurement by all scientists/ easy to convert, based on a unit of 10 3. Convert 200cm to meters. 2m 4. a. How would you measure and calculate the density of a silver bracelet? Find its mass using a triple beam balance and its volume by dropping it into a graduated cylinder filled with water. Calculate the density by dividing the mass by the volume. D = m/V b. How could you check to see if the bracelet truly was silver? Compare it to the density of silver or use other physical and chemical properties. Unit 2 – Describing Matter Key terms: Matter, Physical property, Chemical property, physical change, chemical change, solubility, element, compound, mixture, homogeneous, metal, nonmetal, metalloid, solid, liquid, gas, organic compound, heterogeneous, malleability, ductility, luster, reactivity, combustibility, precipitate, Law of Conservation of Mass 1. Give 2 examples of physical properties. Color, size, shape, state of matter, solubility, lustre, malleability, ductility 2. Give 2 examples of chemical properties. Reactivity, flammability, pH, combustibility 3. Is there a change in identity when observing physical changes? No, physical changes don’t change the identity of the substance. Example: If I cut my hair, it’s still hair, just a different shape/size. 4. Give an example of a physical change. Crumpling up my paper, melting chocolate 5. Give an example of a chemical change. Burning, exploding, rusting, souring, rotting 6. What are the four signs that a chemical change is taking place? Unexpected color change Gas released Precipitate forms Production of light, heat, sound, or odor 7. How are elements, compounds, and mixtures different? Elements are on the Periodic Table, made up of one substance. Compounds are substances that are chemically combined and separated. Mixtures are substances that are physically combined and separated. Unit 3a – Chemistry (Part One) Key terms: proton, neutron, electron, atomic number, atomic mass, isotope, Dalton, Thomson, Rutherford, Bohr, Schrodinger and Heisenberg, Atom, Atomic mass unit (amu), atomic symbol, Valence electrons, period, group, family 1. Briefly list the contributions of Dalton, Thomson, Rutherford, and Bohr in constructing the modern model of the atom. Dalton- All substances are made of atoms. Atoms of the same element are exactly alike; atoms of different elements are different. Thought an atom looked like a solid round ball. Thomson – Discovered the electron. Thought an atom looked like “plum pudding” with the pudding being the positively charged “goo” and the electrons were like plums scattered around in the pudding. Rutherford- Through his gold foil experiment, discovered that most of the mass was in the nucleus and the rest of the atom is mostly empty space with electrons around the nucleus somewhere. Bohr – The “Bohr Model” has the protons and neutrons in the nucleus and the electrons on rings (definite paths) around the nucleus. 2. Calculate the number of protons, neutrons, and electrons for carbon-12. Carbon-12 = 6 Protons, 6 electrons, 6 neutrons 3. What is the mass of a proton, neutron, and electron? Proton: 1 amu. Neutron: 1 amu. Electron: about 0 amu. 4. How do you find the atomic number and atomic mass of an element? Look at the periodic table. The atomic number is the smaller number at the top, and tells you the number of protons in the atom. The atomic mass is the larger number at the bottom, and tells you the average atomic mass (protons + neutrons) of the element. 5. What do the period and the group of an element tell you? Periods are the rows going across (horizontally). There are 7 periods. Periods follow a pattern with the left side being very reactive metals, the middle only a little reactive, the right side being very reactive nonmetals, and the very last element in the period inert (nonreactive). Groups are the columns going up/down. Because elements in the same group share the same number of valence electrons, they share similar properties. 6. Name the eight families of the periodic table. Alkali metals (group 1) – Very reactive metals, never found uncombined in nature, 1 valence electron. Alkaline earth metals (group 2) – Also very reactive metals, but slightly less so than group 1. Never found uncombined in nature, have 2 valence electrons. Transition metals (groups 3-12) – Somewhat reactive, properties and valence electrons vary. BCNO family (groups 13-16) – The only family that contains metalloids; also nonmetals and metals. Reactive. Have 3-6 valence electrons. Halogens (group 17) Very reactive nonmetals, never found uncombined in nature. Have 7 valence electrons and react violently with alkali metals. Noble gases (group 18) – These gases have 8 valence electrons, so they are inert (unreactive). All are found in the Earth’s atmosphere in small amounts. Lanthanides – the first of the two rows at the bottom of the periodic table, they are actually transition metals who simply didn’t fit because the periodic table would be too wide. They come after Lanthanum in the periodic table. They are shiny, reactive metals. Actinides – Also found at the bottom of the periodic table, they are transition metals following the element Actinium. All are reactive and radioactive. Unit 3b – Chemistry (Part Two) Key terms: ion, reactants, products, Covalent, Ionic, Acid, Base, pH, neutralization 1. Which class of elements tend to lose electrons? metals 2. List the elements that are inert. Helium, neon, argon, krypton, xenon, radon 3. Compare and contrast ionic and covalent bonding. Ionic bonding is when atoms gain or lose electrons to become ions and the charged ions become attracted to each other forming a bond. Nonmetals tend to “steal” electrons and become negatively charged ions, while metals tend to “ditch” electrons and become positive ions. Covalent bonding is when atoms share electron pairs to form bonds. These bonds typically form between nonmetals. 4. Balance the following equation: ____ Na + ____ H2O → ____ NaOH + ____ H2 2 Na + 2 H2O → 2 NaOH + H2 5. Circle the acids. Underline the bases. Coffee: pH 5/ Coca Cola: pH 4/ Baking Soda: pH 9/ Tide laundry soap: pH 11.5/ Pure Water: pH 7/ Fluids of the stomach: pH 1 Unit 4 – Heat Key terms: temperature, heat, thermal energy, conduction, convection, radiation, absolute zero, conductor, insulator, thermal expansion, Joule, heat engine, solid, refrigeration, heat pump, thermostat, heat engine, liquid, gas, plasma, endothermic, exothermic, freezing, melting, condensation, evaporation, deposition, sublimation, vaporization 1. What are the three temperature scales? Fahrenheit, Celsius, Kelvin 2. How is Kelvin different from the other scales? Kelvin starts at the lowest possible temperature- absolute zero – so it has no negative numbers. 3. What is thermal expansion? The tendency for matter to expand when you increase its temperature. 4. How are heat and thermal energy related? Thermal energy is the total kinetic energy of the particles, and heat is the transfer of that energy from the warmer object to the cooler object. 5. Name the three types of heat energy transfer and give an example of each. Conduction- by direct contact (touching). Example: burn your hand touching a hot stove. Convection – movement in a liquid or gas as the hot rises and cold sinks. Example: convection currents in your house cause you attic to be hotter than your basement. Radiation – transfers thermal energy through space as electromagnetic waves. Example- I feel warm when I stand outside on a sunny day because of solar radiation. 5. Give an example of a material that is a conductor and a material that is an insulator. Conductor – any metal. Insulator- rubber. 6. Name the three states of matter and describe the particle movement of each. Solid – the particles vibrate in place Liquid – particles can move a little more, sliding past each other Gas – the particles break free of one another, moving around quickly, expanding to fill their container. 6. Draw the phase change triangle and label it. Unit 5 – Electricity & Magnetism Key terms: electricity, series circuit, alternating current (AC), parallel circuit, direct current (DC), magnet, static electricity, poles, conduction, magnetic force, induction, electromagnetic induction, conductor, electromagnet, insulator, solenoid, semiconductor, turbine, diode, generator, transistor, electric motor, circuit, transformer, circuit board, light-emitting diode (LED), integrated circuit board, solar cell 1. What is the relationship between resistance and current (Ohm’s Law)? The greater the resistance, the lower the current and vice versa. I = V/R (Ohm's Law) 2. How can you increase the strength of an electromagnet (3 ways)? Add coils/ Add current/ increase size of iron core 3. Draw a series circuit and a parallel circuit with a switch each that turns off all the lights. SERIES 4. What does the Law of Electrical Charges state? Like charges attract and opposite charges repel each other. 5. Name three ways that objects can be charged and explain each. Friction – rubbing two objects together to “shed” the electrons from one onto the other Conduction – transfer of electric charges by direct contact Induction – transfer of electric charges by indirect contact; when a charged object approaches an uncharged object forcing the charges away from the surface and temporarily charging the second object with the opposite charge.
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