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MIDTERM EXAM REVIEW PRACTICE QUESTIONS & PROBLEMS -- These are just sample problems; the midterm will cover all topics that have been taught this year in Chemistry GT. Review past tests, test review sheets, classwork and homework. 1. Label each substance below as an element, compound, homogeneous mixture or heterogeneous mixture. a air b. salt c. concrete d. nitrogen a. homogeneous b. compound c. heterogeneous d. element 2 Determine whether each process below is a physical or chemical change: a salt dissolving in water b. wax melting a. physical b. physical c. paper burning d. baking a cake c. chemical d. chemical 3. Determine the number of significant figures in each measurement below. Then change each to scientific notation: a. 0.001350g 6 sig figs, 1.35 x 10-3 g b. 20.1650g 6 sig figs, 2.0165 x 101 g 4. Fill out the chart below. Then make the metric conversion below: 1000 mm = 1 m 10 dg = 1 g 100 cJ = 1 J 1 kPa = 1000 Pa 5. Element Y has three isotopes. The atomic mass and abundance of each isotope is given below. Find the average atomic mass of Element Y. Isotope 1 42.67amu 29.5% = 12.59 Isotope 2 45.44amu 62.1% = 28.22 Isotope 3 49.99amu 8.4% = 4.20 ____45.01 amu____ 6. Determine the moles of Aluminum if you have 46.5g 46.5 g x 1 mol Al 1.72moles Al 26.98 g Al 7. Label each substance below as ionic or covalent. Write the formula for each, and determine the molar mass (formula mass) of one mole of each. a barium fluoride Ionic BaF2 175.31 g/mol b dinitrogen pentoxide Covalent N2O5 108 g/mol c. iron (III) hydroxide ionic Fe(OH)3 106.85 g/mol C5H8O 84 g/mol d pentacarbon octahydrogen covalent monoxide 8. What is an ionic bond? How is it different from a covalent bond? Ionic-metal with non-metal, transfer of electrons Covalent-2 non-metals, sharing of electrons 9. 1.43x1024 atoms of boron is how many moles? 1 mole B 1.43x10 24 atoms B x 2.38 moles B 6.02 x 10 23 atoms B 10. Complete the table below: Compound Formula Geometry/Shape Angle Polar? CS2 Lewis Diagram Structural Diagram linear 180 Nonpolar NBr3 Pyramidal 107 Polar bent 105 polar Carbon disulfide nitrogen tribromide Each Br should have 3 lone pairs. H2O dihydrogen monoxide 11. Complete the table for the elements below: Element 80 Br Xe Barium-141 Protons 35 54 56 Neutrons Electrons 45 35 77 54 85 56 Noble Gas Notation Electron Configuration # of occupied energy levels Periodic Table Group [Ar]4s23d104p5 4 halogens [Kr]5s24d105p6 5 Noble gasses [Xe]6s2 6 Alkaline earth metals 12. Complete the table for the ions below: Ion Formula Protons sodium ion Na+1 Dot Diagram Neutrons Electrons 11 12 10 8 10 Oxide O-2 8 Zinc ion Zn+2 30 35 28 Anion or Cation? Cation Anion Cation 13. What do members of the same periodic table group have in common? What do members of the same period have in common? Groups-same # of valence electrons, similar chemical properties/reactivity Periods-same # of principal energy levels, same amount of shielding 14. Define electronegativity: The ability of an atom to attract electrons when in a bond Choose the element below with the greatest electronegativity: a copper or bromine Bromine b silicon or lead Silicon 15. Define ionization energy. The energy required to remove an electron Choose the element below with the greatest ionization energy: a copper or bromine Bromine b silicon or lead Silicon 16. Choose the element below with the greatest atomic radius: a copper or bromine copper b silicon or lead lead 17. Write out the correct orbital diagram for oxygen in its ground state. 18. Write the nuclear reactions below: a. 204 Hg decomposes and releases an alpha particle 204 Hg 4He 200Pt 80 2 78 b. 140Ba decomposes and emits beta decay with gamma emission 140 Ba 0 e 0 140La 56 1 0 57 19. The half life of astatine is 8 1/2 hours. What mass of a 300.0g sample of astatine will remain after 34 hours? Time (hrs) 0 8.5 17 25.5 34 Mass 300.0 g 150.0 g 75.0 g 37.5 g 18.75 g 20. List the diatomic elements. Br2, I2, N2, Cl2, H2, O2, F2 21. What are the quantum numbers for each of the 4 electrons in Beryllium? N l ml ms 1 0 0 +1/2 1 0 0 -1/2 2 0 0 +1/2 2 0 0 -1/2 22. Complete the following nuclear equation: 244U 4 2 He + 240Th What type of radiation is this? ___alpha_____________________ 23. If a piece of metal has a mass of 36.30 g and a volume of 45 L, what is its density? D=m/v D=36.30 g/45 L D=0.81 g/L 24. What will the principal quantum number and the angular momentum quantum number be for the last electron added in Krypton? n=4, l=1 25. What is the frequency of red light with a wavelength of 692 nm? (1 m = 109 nm, speed of light = 3.00×108 m/s) c 3.00 x10 8 m/s 692 x 10 -9 m 4.34 x 1014 s -1