Chemical bonding
Molecular Geometry
Gases
Major Concepts
Miscellaneous
100
Draw the resonance structures for the nitrate ion (NO3-).
see pg 310 in the book
100
Draw or model (with modeling kit) a tetrahedral molecule. Describe how it would change if the shape were to become trigonal pyramidal? or Bent?
see pg 337 in book.
100
Define pressure in terms of force and area
P=F/A
100
Define the octet rule
What is the rule that atoms tend to gain, lose, or share electrongs until they are surrounded by eight valence electrons?
100
What is the equation for the idea gas law? What does each variable stand for?
PV=nRT
200
Draw the resonance structures for Benzene (C6H6)
See pg 311 in the book
200
Which of the following statements about the S–O bond in SO2 is incorrect? a. The S–O bond is nonpolar and there is a partial negative charge on the S. b. The S–O bond is nonpolar and there is a partial negative charge on the O. c. The S–O bond is polar and there is a partial negative charge on the S. d. The S–O bond is polar and there is a partial negative charge on the O. e. The S–O bond is ionic and there is a negative charge on the O.
d {since the atoms are close to one another and are nonmetals the bond is a covalent one (eliminates choice “e”); since the atoms are different the bond is polar (eliminates choices “a” and “b”); since ENO > ENS the partial negative charge resides on O (eliminates choice “c”)}
200
Distinguish between diffusion and effusion
Diffusion is the spread of one substance throughout a space or throughout a second substance. Effusion is the escape of gas molecules through a tiny hole.
200
The ability of an atom in a molecule to attract electrons to itself
What is electronegativity
200
Distinguish between a sigma bond and a pi bond in terms of orbital overla and bond order.
pgs 351-352 in book.
300
Which of the following bonds are polar: B-F, Cl-Cl, Se-O, H-I? What is the direction of polarity in each molecule/bond?
All are polar except Cl-Cl
300
Write the entire molecular electronic configuration including core electrons and determine the bond order for each molecule. a. Li2- b. B2-
a. (σ1s)2(σ1s*)2(σ2s)2(σ2s*)1; BO = 0.5 {BO = (4 – 3)/2 = 1/2} b. (σ1s)2(σ1s*)2(σ2s)2(σ2s*)2(π2p)3; BO = 1.5 {BO = (9 – 4)/2 = 3/2}
300
10.65: A mixture containting 0.765 mol He(g), 0.330 mol Ne(g), and 0.110 mol Ar(g) is contained in a 10.00L vessel at 25 degrees C. -Calculate the partial pressure of each gas in the mixture. -Calculate the total pressure of the mixture.
P He = 1.87 atm P Ne = 0.807 atm P Ar = 0.269 atm Ptotal = 2.95 atm
300
46. Which of the following statements is incorrect? a. To reduce lone pair-lone pair electron repulsions in an octahedral electron domain geometry, the first lone pair of electrons are placed in one of the four equatorial positions rather than the axial positions since the six locations are not equivalent. b. A polar molecule placed in a microwave will heat up when the microwave is turned on. c. Pi bonds are created by unhybridized atomic p orbitals overlapping. d. When forming a bond, if the atomic nuclei distance decreases past the minimum energy, electron-electron and proton-proton repulsions increase the system’s energy. e. Sigma bonds have electron density that lies on the internuclear axis.
A {the six locations in an octahedral electron domain are equivalent; in addition, they are generally not referred to as equatorial and axial}
300
Draw the lewis dot structure for NH3 and describe its electron-domain geometry, molecular geometry, and bond angles.
See pg 336 in book
400
Write the chemical equation for the first electron affinity step for fluorine?
What is F(g) + e- → F(g)-
400
How many of these molecules have a tetrahedral electron domain geometry around the central atom? CCl4 SF4 SiCl4-2 SeI2 KrF2
2 {CCl4: tetrahedral; SF4: trigonal bipyramid; SiCl4-2: trigonal bipyramid; SeI2: tetrahedral; KrF2: trigonal bipyramid}
400
10.33: Suppose you are given two 1 L flasks and told that one contains a gas of MM 30, the other a gas of MM 60, both at the same Temp. The pressure in flask A is Xatm, and the mass of gas in flask A is 1.2g. The pressure in flask B is .5Xatm, and the mass of the gas in flask B is 1.2g. Which flask contains the gas of MM 30, and which contains the gas of MM 60?
Flask A contains gas with 30 g/mol and Flask B contains gas with 60 g/mol
400
Describe Boyles Law
The volume of a fixed quantity of gas maintained at constant temperature is inversely proportional to the pressure. (PV = constant or V = constant x 1/P)
400
12. Which of the following statements is incorrect? a. Ionic bonding results from the complete transfer of electrons from one atom to another. b. Dipole moments are the result of unequal electron distribution in a molecule. c. The electrons in a polar bond are found nearer to the more electronegative element. d. A molecule with very polar bonds can be nonpolar. e. Linear molecules cannot have a net dipole moment.
E
500
Define lattice energy and describe how it fits into the Born-Haber Cycle
LATTICE ENERGY - it is the process of separating 1 mol of an ionic solid into individual ions in the gas phase. For example, the reaction for the lattice energy of CaO is: CaO(s) → Ca+2(g) + O-2(g)
500
Write out the steps and types of reactions in the Born-Haber Cycle.
X(g) → X+(g) + 1e- X+(g) → X+2(g) + 1e- X(g) + 1e- → X-(g) X-(g) + 1e- → X-2(g) X–X(g) → 2X(g) X(s) → X(l) X(l) → X(g) X(s) → X(g) AnBm(s) → A+m(g) + B-n(g) A(s) + B2(g) → AB2(s) To do these cycles: IE1 (1st ionization energy) IE2 (2nd ionization energy) EA1 (1st electron affinity) EA2 (2nd electron affinity) D (bond enthalpy) ΔHfus (heat of fusion; page 439) ΔHvap (heat of vaporization; page 439) ΔHsub (heat of sublimation; page 439) ΔHlatt (latticeenergy) ΔHf (heatofformation)
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