CHM 130 HW2 Ch. 5-9 Spring 2018 Instructor: Name: KEY

Size: px

Start display at page:

Download "CHM 130 HW2 Ch. 5-9 Spring 2018 Instructor: Name: KEY"

Annice Holmes
5 years ago
Views:

1 CHM 130 HW2 Ch. 5-9 Spring 2018 Instructor: Name: KEY Due Friday March 9 by noon, no later. Print these pages out and write on them. 1. As wavelength decreases, frequency increases and energy increases. 2. Fill in the blanks in this electromagnetic spectrum: Gamma X ray UV _visible IR microwave radio & TV 3. Which scientist described a particle of light as a photon? Planck 4. Which scientist said that electrons orbit the nucleus in distinct energy levels? Bohr 5. Gases in discharge tubes give off emission line specta. Explain this process in your own words. Gases in discharge tubes gain energy when plugged in. That energy allows an electron to jump to a higher orbit as it absorbs the energy. Then the electron relaxes by jumping back to its original orbit and in the process must release energy. This energy is released as a wave of light. The emission line spectra is just the unique colors emitted by the atoms in the glass discharge tubes. Each atoms emits a unique selection of waves unlike any other atom. 6. How many electrons can fit into the fourth energy level? How many electrons can fit into a p sublevel? 6 8. How many orbitals are in an f sublevel? 7 9. How many orbitals are on the third energy level? How many electrons can fit on the second energy level? How many electrons can fit into an orbital? How many sublevels are on the third level? Write electron configurations for the following atoms and ions: a. Ca 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 b. F 1s 2 2s 2 2p 5 c. O 2-1s 2 2s 2 2p 6 d. K + 1s 2 2s 2 2p 6 3s 2 3p 6 e. P 1s 2 2s 2 2p 6 3s 2 3p 3 f. Cl - 1s 2 2s 2 2p 6 3s 2 3p How many valence electrons do the following atoms have? a. N 5 b. Ga 3 c. I 7 d. Ca 2

2 15. What does a magnesium atom want to do in order to become stable like a noble gas? Mg wants to lose 2 outer valence electrons so it will have 10 electrons just like Ne, and thus be stable and low in energy and happy. It will then have a +2 charge as an ion. 16. What does a sulfur atom want to do in order to become stable like a noble gas? S wants to gain 2 electrons so it will have 18 electrons like Argon. This makes S 2-,a -2 ion in charge, and it is happy, stable, and low in energy. 17. What are the charges for the following when they become ions? a. Ca +2 b. P -3 c. Al +3 d. S -2 e. K N 3- is isoelectronic with what atom? Ne 19. Mg 2+ is isoelectronic with what atom? Ne 20. Fill in this table for these atoms and ions: Atoms or Ion 79 Br 79 Br - 41 Ca 41 Ca 2+ # protons # electrons # neutrons mass In which group is potassium? Alkali metals 22. In which group is gold and silver? Transition metals 23. Why is a phosphorus atom smaller than an aluminum atom when phosphorus s mass is larger than aluminum s? (Do not quote the trend explain!) The mass of an atom is all in the nucleus (protons and neutrons) and does not determine the size. The electrons orbiting the nucleus determine the size. P has 15 protons than pull its electrons in close. Al has only 13 protons that pull its electrons in not quite as closely. Both Al and P are filling electrons in on the 3 rd level or 3 rd orbit. So P having a greater positive pull in the nucleus due to more protons is actually smaller than Al. 24. Which atom is largest? a. Ba b. Mg c. Cl d. At 25. For each PAIR, circle which is larger: a. Mg or Mg 2+ b. Si or Si 4+ c. Se or Se 2-

3 26. Define ionization energy in your own words: Ionization Energy is the energy needed to remove an outer electron from an atom. 27. True or False? IE is generally high for small atoms. true 28. True or False? IE is generally very low for nonmetals. false 29. Explain why the IE for bromine is higher than the IE for calcium (Do not quote the trend explain!) Br is a nonmetal that wants to gain more electrons. So losing an electron is the wrong direction for Br. Br holds only its electrons very tightly so removing one electron takes a lot of energy. Ca meanwhile wants to lose electrons. Ca does not hold onto its outer electrons very tightly so removing one takes very little energy. 30. Define electronegativity: Electrongativity is the ability of a bonded atom to pull the bonded electrons close. 31. What is the most electronegative element? F 32. Noble gases are very stable and inert. Why? What is so special about them? Noble gases have full s and p sublevels s 2 p 6 (He is just 1s 2 ) and this is a very stable and low energy configuration. Noble gases are very happy with their 8 outer valence electrons (He has 2 valence electrons) and thus they do not bond naturally and are inert. 33. True or False? When atoms gain and lose electrons a covalent bond can form. false 34. True or False? When atoms share electrons a covalent bond can form. true 35. True or False? Anions are larger than their corresponding atom. true 36. Circle the covalent molecules: CO 2 CaBr 2 KF N 2 O H 2 O True or False? Breaking a bond is endothermic. true 38. True or False? Sharing 6 electrons is called a double covalent bond. false

4 39. Draw Lewis dot structures for the following: PCl 3 # val e - = 26 N 2 O # val e - = _16 Polar bonds? Yes or No Polar molecule? Yes or No Shape: trigonal pyramid 40. Draw lewis dot structures for the following ions: Polar bonds? Yes or No or One of each Polar molecule? Yes or No Shape: linear NO 2-1 # val e - = _18 PO 4 3- # val e - = _32_ Shape: bent Shape: tetrahedral Circle the bond if it is polar: C-H P-O S-S H-Cl Br-Br C-F 42. Add the delta notation above for each polar bond and the polarity arrow. 43. Write the correct formulas for the following compounds; a. strontium acetate Sr(C 2 H 3 O 2 ) 2 b. magnesium cyanide Mg(CN) 2 c. potassium nitride K 3 N

5 d. nickel(iii) phosphide NiP e. phosphorus pentachloride PCl 5 f. cobalt(ii) sulfite CoSO 3 g. Aluminum sulfate Al 2 (SO 4 ) 3 h. carbon tetrafluoride CF 4 i. silicon dioxide SiO 2 j. gold(iii) iodide AuI 3 k. barium nitrite Ba(NO 2 ) 2 l. sodium sulfide Na 2 S m. iron(iii) nitrate Fe(NO 3 ) Write the names for the following compounds: a. NiBr 3 nickel(iii) bromide b. SF 2 sulfur difluoride c. P 2 O 5 diphosphorous pentaoxide d. Fe(C 2 H 3 O 2 ) 2 iron(ii) acetate e. CdS cadmium sulfide f. PbO 2 lead(iv) oxide g. SnBr 2 tin(ii) bromide h. NaI sodium iodide i. Al 2 (SO 4 ) 3 aluminum sulfate j. SO 3 sulfur trioxide k. CaCl 2 calcium chloride l. K 2 CrO 4 potassium chromate m. MnSO 4 manganese(ii) sulfate 45. What ion does an Arrhenius acid produce in water? H What ion does an Arrhenius base produce in water? OH Circle the Arrhenius acid in this reaction: HCl(aq) + KOH(aq) KCl(aq) + H 2 O(l) 48. Circle the Bronsted Lowry base in this reaction: HBr(aq) + NH 3 (aq) NH 4 + (aq) + Br - (aq)

6 49. Which of the following is a strong base? C a. b. c. d. 50. Give the names for three strong acids: hydrofluoric acid, nitric acid sulfuric acid 51. Give the names for two weak acids: carbonic, acetic, phosphoric, hydrofluoric acid 52. If the ph is 8, the solutions is: a. acidic b. neutral c. basic 53. Circle the soluble compounds: AgBr CaCO 3 AlPO 4 MgSO 4 Ba(OH) Draw the following electrolytes in beakers of water: NaNO 3 KBr AlPO 4 MgS 55. If [H + ] is 10-5 then the ph = If [H + ] is then the ph = How is a strong electrolyte different from a weak electrolyte and from a non-electrolyte? Strong ionizes completely, weak ionizes somewhat, and non ionizes not at all. 58. What topic is still giving you trouble in CHM 130? Not graded.

Regents Chemistry Unit 3- Bonding, Moles & Stoichiometry Study Guide & Pre-Test KEY

Name: Regents Chemistry Unit 3- Bonding, Moles & Stoichiometry Study Guide & Pre-Test KEY Focus Questions for the Unit: How are compounds different... from elements?... from mixtures? What role do valence