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Game Face: Quarter Test Review Answers You’re Welcome, Please use responsibly. 1. Put the following into scientific notation: a. b. c. 2. 2,000,000 m 0.0250 mL 690 g 2.0 X106 2.50 X 10-2 6.90 X 102 Put the following into standard notation: a. b. c. 4.50x105 mg 9.45x10-3 kL 3.0x108 m/s 450000 .00945 300000000 3. Explain how to count the number of significant figures in a number that is written for you. Atlantic and Pacific decimal Absent start at right and count at 1 st non-zero number. Present start at left count at 1st non-zero number 4. Explain how you know how many significant figures to keep in the laboratory. Measured and To one estimated digit 5. Read the following picture to the correct number of significant figures. 41.60 the zero is estimated 6. Answer the following problems to the correct number of significant figures. a. b. c. 7. 8. 9. 2.895 + 3.45 = 5.5 x 5.5 = 7.00 6.90 2.50 6.35 3.0X101 .040 Convert the following numbers accordingly: a. b. c. 250g kg 6.94L mL 1.90dag g .250 kg 6940 mL 19.0 g Define accuracy, precision, and error. Accuracy-closeness to accepted value. Precision- closeness to other measurements What is the formula used to find percent error? /Experimental-accepted/ X 100 Accepted 10. Label the following according to both their accuracy and precision. 1st Neither accurate Or precise 2nd precise 3rd Both accurate and precise 11. In the lab a group of students found the density of lead to be 12.1g/mL. However, you know the actual value of lead to be 11.43g/mL. What is the percent error in the students’ work to the correct number of significant figures? /12.1 – 11.43/ X 100 = 5.86 % error 11.43 12. What is the difference between a qualitative and quantitative measurement? Give an example of each. Qualitative – quality , not specific. he is tall Quantitative – quantity, using numbers He is 2 meters tall 13. What questions would you ask yourself to determine whether you were observing a chemical or a physical property? Is the change forming a new compound or substance with a different composition 14. Please list three physical and three chemical properties. Physical - Hardness, density, color, Melting/boiling point Chemical – ability to rust, burn , rot, decay, spoil 15. Label the following as chemical or physical properties of matter: a. The ability to rust Chemical c. The ability to boil Physical b. The ability to rot Chemical d. The ability to dissolve Physical 16. What is the difference between a period and a group on the periodic table? What is another name for a group? Please give two examples of groups on the periodic table. Period =Horizontal, Group= Veritcal column Group =Family Alkali Metals, Halogens, Noble Gases, Alkaline Earth Metals, Transition Metals 17. Please label all the parts of the periodic table that we have talked about. Including but not limited to halogens, alkali metals, d-block, noble gases, etc… 18. While going through a chemical stockroom we find a bottle containing an unknown substance. We measure the mass of the substance to be 25.2g and the volume to be 3.19mL? What is the density of the substance? 25.2g/3.19mL= 7.90 g/ml 19. Calculate the densities of the following two substances. Substane A 20-0/40-0 = .50g/mL Substance B – 7.5/40 = .19g/mL Density Comparison Density Comparison 20 25 15 20 10 5 Mass (g) Mass (g) 25 15 “A” 10 5 0 0 5 10 15 20 25 “B” 30 35 40 45 40 45 Volume (mL) 0 0 5 10 15 20 25 Volume (mL) 30 35 19. Which line on the graph in the previous question has more error if you know that one of the lines is plotted form the theoretical data? Is that line to steep of too shallow? What are two possible sources of error that could have caused the error? Substance A starts at (0,0) which is theoretical. Sub B is to shallow of a slope. Sources of error include labeling wrong axis, not zeroing balance, mismeasuring 20. Explain what we use distillation and chromatography for and discuss their differences. distillation used to separate liquids based on boiling points and chromatography used to separate pigments 21. Is saltwater a heterogeneous or homogeneous mixture? How do you know? heterogeneous – different throughout, homogeneous- the same throughout 22. A solution can be which state(s) of matter? Solid, liquid, gas 23. Explain the difference between a gas and a vapor. Vapor- gaseous substance that is usually a solid or liquid Gas – exist as gas at room tempertaure 24. Is a mixture a physical or chemical combination of two or more substances? Physical six 25. Who are the main contributors’ to atomic theory? Democritus indivisible, indestructible , Dalton- identical and indivisible, Millikan – quantify charge of electron Thomson - plum pudding, discovered electron , Rutherford-nucleus, empty space, Bohr – fixed orbits, planets around the sun, Quantum Mechanical Model – area of high probability to find electron 26. The following pictures were experiments used by whom and proved what? Rutherford’s Gold Foil experiment –discovery of nucleus and atom is empty space A. Thomson’s cathode ray – existence of negative charged electron B. 27. Draw an atom and label all parts. Protons and neutrons in nucleus, electrons in cloud or orbitals around outside 28. The ___atomic________number tells us how many protons an atom contains in its nucleus and is represented by the letter ___Z____. This plus the number of neutrons tells us the ____mass number_______ which is represented by the letter ___A____. The difference between this and the atomic mass is that the atomic mass takes into account the __percent abundance_____ of the different isotopes. In case you have forgotten, isotopes are two or more to the same ___element_____ with different numbers of ____neutrons_____. 29. A bromine isotope has 35 protons, 35 electrons, and 45 neutrons. Its mass number is 35 +45= 80 30. The atomic number of silicon, 14, indicates that there are 14 protons and electrons in a neutral atom Element has two naturally occurring isotopes. The first has a mass of 12g and the second has a mass of 15g. If their percent abundances are 25% and 75% respectively, what is the atomic mass of element ? 12 X .25 = 3 15 X .75 = 11.25 3 + 11.25 = 14.25 as the atomic mass 234 90 Th represent what? 234 is the mass number and 90 is the atomic number 32. How about the number in C-14? 14 Is the mass number of the isotope 31. The numbers in 33. What did Aufbau, Pauli, and Hund have to say about electrons? Aufbau – electrons fill lowest energy levels 1st Pauli Exclusion – 2 electrons per orbital with opposite spin, no two electrons same 4 quantum #’s , Hund’s Rule – orbitals want maximum number of electrons with same spin, Dealing Cards- nobody gets 2 til everybody has 1 3rd 34. How do we determine the number of electrons in a sublevel? How about in a principle energy level? Give two examples of each. S-2 p-6 d- 10 f-14 1st energy level n=1 s orbital 2 e- 2nd n=2 8 e- s and p orbital n=3 18 e- s,p and d orbital 4th n=4 32 e- s,p,d and f orbital 35. Write the electron configurations for the following atoms a. b. c. d. Br 1s2 2s2 2p63s23p64s23d104p5 Au 1s2 2s2 2p63s23p64s23d104p65s24d105p66s14f145d10 Tc 1s2 2s2 2p63s23p64s23d104p65s24d5 36. Write the orbital configurations for N and Cl in the following orbital configurations. this is Hund’s Rule N: Cl: 37. Which substance listed in the table is a liquid at 15.0C? I II III IV Melting Point 21.0C 9.0C -150C 56.0C Boiling Point 125C 86.0C 12.0C 250.0C 38. Which of the following would decrease the solubility of most solid solutes? a. Increasing the temperature b. Increasing the amount of solvent at constant temperature c. Decreasing the amount of solute at constant temperature d. Decreasing the temperature 39. If an unknown sample that has a mass of 21.0g occupies a volume of 12.1cm 3, what is the identity of the unknown? a. Mg b. CH4 c. Na d. Pb 40. Which of the following does not indicate that a chemical change has occurred? a. A precipitate is formed as two aqueous solutions mix b. As a solid is placed into a solution gas is evolved- Example Dry Ice c. As sodium hydroxide is mixed into water the temperature of the water increases d. Heat is evolved as zinc is placed into hydrochloric acid 41. Which idea of Thomson’s atomic model is different than Dalton’s? a. Thomson thought atoms were tiny and indivisible b. Thomson thought that atoms solid c. Thomson thought that atoms were divisible d. Thomson thought that atoms have a nucleus 42. Which of the following is accepted in our current atomic theory? a. Atoms circle the nucleus like planets circle the sun b. Electrons are found in a large, solid, positively charged mass c. Protons and electrons are both found In the nucleus of an atom d. Electrons are found in a cloud around the positive nucleus 43. What is the nuclear (nucleus) composition of potassium – 40? a. 19 electrons + 19 protons correct numbers but electrons not in nucleus b. 21 protons + 19 electrons c. 19 protons + 21 neutrons d. 21 protons + 19 neutrons 44. Which of the following correctly explains the relationship between protons and electrons in a positively charged ion? a. The atom will have more protons than electrons b. The atom will have less protons than electrons c. The number of electrons and protons will be the same d. Not enough information to determine 45. Which of the following electron configurations represents a halogen? a. [Kr] 5s24d105p5 b. [Ne] 3s23p6 c. [Ar] 4s1 d. [Ar] 4s2 46. How many valence electrons does the following element have? 1s22s22p63s23p64s23d104p65s24d7 a. 9 b. 7 c. 2 in the 5th energy level d. 15 47. Consider the Bohr model of the hydrogen atom. How does an electron produce light? a. By absorbing a quanta of energy and moving to an excited state b. By releasing a photon of energy as it returns to the ground state c. By absorbing a photon of energy as it returns to the ground state d. By releasing a quanta of energy and moving to an excited state 48. Which of the following statements is correct when comparing ultraviolet radiation to infrared radiation? a. IR radiation has a higher frequency than UV radiation b. UV radiation has a shorter wavelength than IR radiation c. UV radiation travels at a greater speed than IR radiation d. IR radiation is visible to the naked eye whereas UV is not