Physical Science Midterm Review

Transcription

1 Chapter 1: Science Skills, pages What is science? Science is a system of knowledge and the methods you use to find that knowledge. 2. What is the relationship between science and technology? Science and technology are interdependent. Advances in one lead to advances in the other. 3. Explain the goal of the scientific method, AND list the steps in the scientific method. The goal of the scientific method is to solve a problem or to better understand an observed event. STEPS TO THE SCIENTIFIC METHOD: 1.) Making Observations 2.) Form A Hypothesis 3.) Test The Hypothesis 4.) Draw A Conclusion If the data does not support your hypothesis the hypothesis can be revised and then retest. 4. Define an observation. An observation is information that you obtain through your senses. 5. What is a hypothesis? A hypothesis is a proposed answer to a question 6. Describe the difference between a manipulated variable (independent variable) and a responding variable (dependent variable). The manipulated variable is the variable that causes change in another variable. The responding variable is the variable that changes in response to the manipulated variable. 7. What is the difference between a scientific theory and scientific law? A scientific theory is a well- tested explanation for a set of observations or experimental results and scientific law is a statement that summarizes a pattern found in nature. 8. What is a scientific model, and why is it useful in science? A scientific model is a representation of an object or event. The reason why a scientific model is useful in science is because it makes it easier to understand things that might be too difficult to observe directly. It allows you see objects or events that might be too big/small to be able to see with the naked eye.

2 9. What is the system called that scientists have as a set of measuring units? SI Units (International System Of Units) 10. Complete the following table: Quantity Unit Abbreviation Length Meter m Mass Kilogram kg Time Seconds s Temperature Kelvin K 11. What is the difference between precision and accuracy? Precision is a gauge of how exact a measurement is and accuracy is the closeness of a measurement to the actual value of what is being measured. 12. How do scientists communicate their scientific investigations with one another? Scientists can communicate results by writing in scientific journals or speaking at conferences. Chapter 2: Properties of Matter, pages Define the following terms: a. Pure Substance Matter that always has the exact same composition b. Element A substance that cannot be broken down into similar substances c. Atom The smallest particle of an element d. Compound A substance that is made from two or more simpler substances and can be broken down into those simpler substances e. Heterogeneous Mixture The parts of the mixture are noticeably different from one another. f. Homogeneous Mixture The substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from another. g. Solution When substances dissolve and form a homogeneous mixture h. Suspension A heterogeneous mixture that separates into layers over time i. Colloid Contains some particles that are intermediate in size between the small particles in solution and the larger particles in a suspension.

3 j. Viscosity Resistance to flow k. Malleability The ability of a solid to be hammered without shattering l. Filtration A process that separates materials based on the size of their particles m. Distillation A process that separates the substances in a solution based on their boiling points 2. Look at letters a through m at the question above. Which letters give examples of PURE SUBSTANCES? B & D 3. What is the difference between a physical change and a chemical change? In a physical change the substances in the material stay the same and in a chemical change the substances react and forms one or more new substances. Chapter 3: States of Matter, pages Complete the table for the properties of solids, liquids, and gases. State of Matter Shape Volume Example Solids Definite Definite ice Liquids Variable Definite water Gases Variable Variable Water vapor 2. Describe the fourth state of matter and where it is found. The fourth state of matter is plasma. Plasma is found is the universe. 3. What does the kinetic theory of matter state? The kinetic theory of matter says that all particles of matter are in constant motion 4. Define phase change. A phase change is a reversible physical change that occurs when a substance changes from one state of matter to another. 5. Describe the following phase changes: a. Melting solid to a liquid b. Freezing liquid to a solid c. Vaporization liquid to a gas d. Condensation gas to a liquid

4 e. Sublimation solid to a gas without changing to liquid first f. Deposition gas to a solid without first changing to a liquid 6. Describe the difference between an endothermic and exothermic change. In an endothermic change the system absorbs energy from its surrounding and the exothermic change the system releases energy to its surroundings 7. Which of the phase changes are endothermic? Melting, sublimation, and vaporization 8. Which of the phase changes are exothermic? Deposition, condensation, and freezing Chapter 4: Atomic Structure, pages What was John Dalton s theory about the atom? (Make sure to include all points!) 1.) All elements are composed of atoms 2.) All atoms of the same element have the same mass, and atoms of different elements have different masses 3.) Compounds contain atoms of more than one element 4.) In a particle compound, atoms of different elements always combine in the same way 2. What did J.J. Thomson discover about the atom AND what was his experiment? Thomson s cathode- ray experiment lead to the first evidence that atoms are made of even smaller particles. He created a model called the Plum Pudding Model where negatively charged particles are scattered evenly throughout a positively charged mass. 3. What did Ernest Rutherford discover about the atom AND what was his experiment? Rutherford s experiment is called the Gold Foil Experiment where he aimed a narrow beam of alpha particles at a piece of gold. Many of the beams passed through the gold, but some were deflected, this lead to the discovery of the nucleus.

5 4. Draw an atom of beryllium (Be). Make sure to include the correct number of protons, neutrons, and electrons. ALSO INCLUDE THE CHARGE OF EACH SUBATOMIC PARTICLE. Protons = positive, neutrons = neutral, and electrons = negative 5. What is the formula for finding the number of neutrons in an atom? Atomic number minus atomic mass = neutrons 6. What is an isotope? Isotopes are atoms of the same element that have different neutrons and different mass numbers. 7. Give examples of isotopes of oxygen. Oxygen- 16, Oxygen- 17, and Oxygen What did Niels Bohr discover about the atom? Bohr discovered that electrons move around the nucleus in fixed orbitals, just like planets around the sun. 9. Why is it impossible to determine the exact location of an electron, and what do scientists use when trying to find where electrons are located? Electrons move in a very unpredictable way therefore scientists use the electron cloud model as a visual model of the most likely locations for electrons in an atom. 10. Complete the following table: Element Symbol Atomic Atomic Protons Neutrons Electrons Number Mass Silicon Si Silver Ag Mercury Hg Oxygen O

6 Chapter 5: The Periodic Table, pages How did Dmitri Mendeleev arrange his periodic table? Mendeleev arranged the elements into rows in order of increasing mass so that elements with similar properties were in the same column. 2. Explain what a period is on the periodic table. The periods are the rows on the periodic table. Each row on the periodic table identifies how many orbitals each atom has. For example, Sodium is in the third row, which means it has three orbitals (shells). 3. Explain what a group is on the periodic table. Each column on the periodic table is called a group. Elements within each group have similar properties. 4. Where are the metals, nonmetals, and metalloids found on the periodic table? ALSO, Give 2 properties of each. Metals are found left of the metalloids on the periodic table. 1.) Good conductors of electric currents and heat 2.) Most are solid, malleable, and ductile Nonmetals are found to the right of the metalloids 1.) Poor conductors of electric current and heat 2.) Low boiling points and most are gases Metalloids are found on the staircase of the periodic table 1.) Have properties between metals and nonmetals 5. What is the pattern within the elements as you go from left to right on the periodic table? As you move from left to right on the periodic table the elements become less metallic and more nonmetallic. 6. What is a valence electron and WHY is it important? A valence electron is an electron that is in the highest occupied energy level of an atom (the outermost shell). A valence electron is important they play a key role in chemical reactions. 7. Complete the following table about groups on the periodic table: Group Number Family Name Valence Electrons Properties 1A Alkali Metals 1 Highly reactive metals. Reactivity increases as you move down the column. Found in nature as compounds

7 2A Alkaline Earth Metals 2 Harder metals than those in group 1A. Differences in reactivity is shown by how they react with water. 3A Boron Family 3 Aluminum is the most abundant metal in the Earth s crust. Boron, silicon, and oxygen are used to create glass 4A Carbon Family 4 Metallic nature of the elements increase from top to bottom. 5A Nitrogen Family 5 Wide range of physical properties. 6A Oxygen Family 6 Has metalloids and nonmetals 7A Halogens 7 Most reactive nonmetals. Reactivity decreases as you work your way down the column, 8. What are the two most reactive groups on the Periodic Table? Alkali metals and Halogens Chapter 6: Chemical Bonds, pages Draw the electron dot diagrams for magnesium, phosphorus, and neon.

8 2. When does an atom become an ion? An ion is when an atom gains or loses an electron 3. What is an ionic bond? An ionic bond is the force that holds cations and anions together. An ionic bond forms when electrons are transferred from one atom to another. This type of bond occurs between a metal and non- metal. 4. What is a covalent bond? A covalent bond is a chemical bond in which two atoms share a pair of valences electrons. This type bond occurs between a nonmetal and a nonmetal. 5. What is a polar covalent bond? A polar covalent bond is when electrons are not shared equally. 6. Name the following compounds: *Make sure to determine if it is ionic or covalent before you decide how to name it! a. MgCl2 Magnesium Chloride b. Al2O3 Aluminum Oxide c. S2F4 Disulfur Tetrafluoride d. P5Cl Pentaphosphorus Monochloride 7. Write the formulas for the following compounds. *Make sure you determine if it is ionic or covalent before you decide how to write the formula! a. Decanitrogen pentabromide N10Br5 b. Sodium sulfide Na2S c. Dihydrogen monoxide H2O d. Gallium chloride GaCl3 8. Draw the bond that forms between beryllium and sulfur. Name the newly formed compound, and write the chemical formula of the compound. Formula: BeS Name: Beryllium Sulfide

9 9. Draw the bond that forms between carbon and fluorine. Name the newly formed compound, and write the chemical formula of the compound. Formula: CF4 Name: Carbon Tetrafluoride 10. What is a metallic bond? A metallic bond is the attraction between a metal cation and the shared electrons that surround it. Chapter 7: Chemical Reactions, pages Define the following: a. Reactant The substances that undergo change (the starting material) b. Product The new substances formed as a result of that change (the ending material) c. Chemical equation Is the representation of a chemical reaction in which the reactants and products are expressed as formulas. 2. What does the law of conservation of mass state? The law of conservation of mass states that matter cannot be created or destroyed in a chemical reaction. 3. Use the following chemical reaction to answer the following questions: CH4 + O2! CO2 + H2O a. What are the reactants in this equation? CH4 + O2 b. What are the products in this equation? CO2 + H2O c. Why does this equation need to be balanced? To show that mass is conserved during the reaction. d. Balance the above equation. CH4 + 2O2! CO2 + 2H2O 4. Balance the following equations:

10 H2SO4 + 2NaOH! 2H2O + Na2SO4 Ca + 2H2O! Ca(OH)2 + H2 3Fe2O3 + CO! 2Fe3O4 + CO2 5. Explain how temperature, surface, area and concentration could affect the rate of a chemical reaction. Temperature: An increase in temperature will increase the reaction rate. Similarly, decreasing temperature will decrease the reaction rate. Surface Area: An increase in surface area will result in an increase of the exposure of reactants to one another.the greater the exposure, the greater the reaction rate. Concentration: Concentration refers to the number of particles in a given volume. Concentration is like the strength of the substance. The higher the concentration of a substance the higher the reaction rate