Basic Chemistry Problem Set 1. Indicate whether each of the following changes is a physical changes or a chemical changes. a) Iron rusts b) Water begins to boil c) Grass grows d) Food is digested e) Ingested salt dissolves in blood Chemical Physical o o o o o o o o o o 2. Write the chemical symbol for each of the following atoms. a) Iron b) Chlorine c) Sodium d) Phosphorus e) Calcium 3. Write the name of each of the following atoms. a) S b) P c) Mg d) C e) N 4. Complete the following table (A Periodic Table of the Elements is appended). Name Nitrogen Neutrons Atomic Number Mass Number Symbol 6 16 31 11 Magnesium 22 24 56 26 1 Fe 5. For each of the following pairs of atoms indicate if they are likely to form ionic bonds, covalent bonds or polar covalent bonds or both? a) P and Cℓ b) Na and Ca c) Na and O d) H and C e) Fe and N f) H and Cℓ g) Cℓ and Cℓ h) C and O i) P and Fe j) N and Cℓ Covalent bonds Polar covalent bonds Ionic bonds o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o 6. Circle all of the following statements concerning pH which are true. i) ii) iii) iv) Solutions cannot have pH values greater than 14 Very acidic solutions have a large number of H+ ions present Pure water has a pH = 7. Acidic solutions have pH < 7. 2 7. Classify the following statements as True or False. If the statement is False, re-write the statement to make it True. a) Bond polarity arises from differences in electronegativity between two covalently bonded atoms. TRUE FALSE o o o o o o o o o o o o o o o o o o o o If False: b) The electronegativity of atoms decreases down a group in the Periodic Table of Elements. If False: c) When an atom has a large number of neutrons, it will have a large electronegativity. If False: d) Electronegativity arises because some atoms are capable of attracting protons better than others. If False: e) Water is the human body’s main solvent because it can dissolve most polar molecules. If False: f) Some physical properties of molecules, such as boiling points, are entirely dependent on individual bond polarities. If False: g) Hydrogen bonding is responsible for the high boiling point of water. If False: h) The low boiling point of nitrogen is due to hydrogen bonding between nitrogen molecules. If False: i) Hydrogen bonding is very important in biological systems such as for holding the strands of DNA together. If False: j) Hydrogen bonding is a specific example of ionic bonding when hydrogen atoms from two different molecules attract each other. If False: 3 8. Classify the following statements as True or False. If the statement is False, re-write the statement to make it True. a) When covalent molecules dissolve in water, they break apart. True False o o o o o o o o o o o o o o o o o o o o If False: b) Salts are electrolytes because they release ions when dissolved in water. If False: c) A cation is a positively charged ion. If False: d) An anion is a negatively charged ion. If False: e) An acid is a substance that produces H+ when dissolved in water If False: f) Stomach acid is primarily hydrochloric acid. If False: g) Ammonia is a very important acid formed through the breakdown of muscle protein. If False: h) Sulfuric acid is a strong acid. If False: i) Carbonic acid transports carbon dioxide in the body. If False: j) Sodium bicarbonate is a weak base that is often used to reduce stomach acid. If False: 4 Periodic Table of the Elements 1 2 H He 1.0079 4.0026 3 4 5 6 7 8 9 10 Li Be B C N O F Ne 6.941 9.0122 10.811 12.0107 14.0067 15.9994 18.9984 20.1797 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar 22.990 24.3050 30.9738 32.066 35.4527 39.948 26.98154 28.0855 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 39.0983 40.078 44.956 47.867 50.9415 51.996 54.938 55.845 58.9332 58.6934 63.546 65.39 69.723 72.61 74.9216 78.96 79.904 83.80 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 85.4678 87.62 88.906 91.224 92.906 95.94 98 101.07 102.9055 106.42 114.818 118.710 121.760 127.60 126.9045 131.29 107.8682 112.411 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 222 132.9054 137.327 138.906 178.49 180.9479 183.84 186.207 190.207 192.217 200.59 204.3833 207.2 208.9804 209 210 87 88 89 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Uuq Uup Uuh Uus Uuo [265] [268] [271] [270] [277] [276] [281] [280] [285] [284] [289] [288] [293] [294] [294] 223 226.0254 227.0278 59 195.078 196.9666 60 61 62 63 64 65 66 67 68 69 70 71 140.9076 5 Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 144.24 145 150.36 151.964 157.25 158.925 162.50 164.930 167.26 168.934 173.04 174.967 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr 244 243 247 247 251 252 257 258 259 262 58 Ce 140.116 Pr 232.0381 231.0359 238.0289 237.0482 5