Chemical bonding 2
1- Which of the following pairs of atoms will form a polar covalent bond? Choose from : C & S, H & B, O& O, Mg & Br, K & Cl
2- How many double bonds must be formed to write the correct Lewis Structure for NCl3?
3- Consider the following three structures for the thiocyanate ion. Which of these structures has an atom with a formal charge of -1?
4- Which of the following elements can have an expanded octet? Choose from: O,Cl, N, H, He
5- How many equivalent resonance forms can be drawn for the sulfur trioxide (SO3) molecule?
6- Consider the molecules PCl3, PCl5, and SiH4. Which of these molecules is polar?
7- Consider the correct Lewis structure for the hypothetical molecule ZQ2 that is shown in the figure. Which of the following is closest to the expected Q-Z-Q bond angle in this molecule?
8- What is the hybridization of the carbon atom indicated by the arrow in the following figure?
9- What will be the electron geometry in a molecule with three bonding domains and one lone pair of electrons around the central atom?
10- How many sigma and pi bonds are present in the molecule depicted?
11- What types of intermolecular forces will be present in a pure sample of the compound shown in the figure?
12- Which of the following would you expect to have the highest boiling point? Choose from: C8H18, CH4, C4H10, C2H6, C3H8
13- Consider the following phase diagram. If a substance were to start at the temperature and pressure indicated by the x, what phase change would occur as the result of decreasing the pressure at constant temperature?
14- How much energy (in kJ) is necessary to convert 2.50 mol of ethanol from liquid to gas at 78.3 oC?
15- Which of the following species can hydrogen bond with water? Choose from: CH4, H2S,HF, H2Se, CH3Cl
16- Use the table to answer questions about bond energies.
Bond / Bond energy(kJ/mol)
C−C / 347
C=C / 611
C−H / 414
C−O / 360
C=O / 799
O−O / 142
O=O / 498
H−O / 464
Part A
Calculate the bond energy for breaking all the bonds in a mole of methane, CH 4 .Express your answer to four significant figures and include the appropriate units.
Part B
Calculate the bond energy for breaking all the bonds in a mole of O 2 molecules? Express your answer to three significant figures and include the appropriate units.
Part C
Calculate the bond energy for forming all the bonds in a mole of water molecules, H 2 O .Express your answer to three significant figures and include the appropriate units.
Part D
Calculate the bond energy for forming all the bonds in a mole of carbon dioxide, CO 2 .
Express your answer to four significant figures and include the appropriate units.
17- Consider the following four molecules. Which of these satisfy the octet rule and which do not? PF5,CS2,BBr3,CO3-2
18- How many lone pairs are on the central atom in BCl 3 ?
19- How many lone pairs are on the central atom of BrF 3 ?
20- The Lewis structure for the chlorate ion isCalculate the formal charge on the chlorine (Cl ) atom. Express your answer as an integer. Calculate the formal charge on each of the oxygen (O ) atoms labeled a , b , and c in the following Lewis structure. Express your answers as integers separated by commas.
21- What are the formal charges on the sulfur (S ), carbon (C ), and nitrogen (N ) atoms, respectively, in the resonance structure that contributes most to the stability of the thiocyanate ion, SCN − ?
The possible resonance structures for the thiocyanate ion, SCN − , are
Express your answers as integers separated by commas.
formal charge on sulfur (S ), carbon (C ) and nitrogen (N ) atoms =