Covalent Bonding and Molecular Structure (key)

Transcription

1 ovalent Bonding and Molecular Structure (key) AX 2 : 2 1. What is the bond angle? Which element is more electronegative, carbon, or oxygen? xygen 3. Would you expect 2 to be a polar or a nonpolar molecule? Explain. Polar. Even though it is composed of polar bonds, the two bonds are located opposite one another and their affect will cancel each other. arbon Dioxide ( 2 ) Valence Electrons: 16 ybridization: = sp, = sp 2 Electronic Geometry: Linear Molecular Geometry: Linear

2 AX 3 : B 3, N 3, What is the B bond angle in B 3? What is the N bond angle in N 3? What is the bond angle in 3 2? s the electron density in the B bond of B 3 oriented closer to fluorine, or to boron? luorine 5. What is the average bond order for the N bonds in the nitrate ion? 1 1 / 3 6. What is the average bond order for the bonds in the carbonate ion? 1 1 / 3 Boron Trifluoride (B 3 ) B Valence Electrons: 24 ybridization: B = sp 2, = sp 3 B Electronic Geometry: Trigonal Planar Molecular Geometry: Trigonal Planar Nitrate (N 3 ) N N Valence Electrons: 24 ybridization: N = sp 2, = sp 2 Electronic Geometry: Trigonal Planar Molecular Geometry: Trigonal Planar (1 of 3 resonance structures) arbonate ( 3 2 ) 2 2 Valence Electrons: 24 ybridization: = sp 2, = sp 2 Electronic Geometry: Trigonal Planar Molecular Geometry: Trigonal Planar (1 of 3 resonance structures)

3 AX 2 E: S 2, Sn 2 1. What is the S bond angle in S 2? < What is the Sn bond angle in Sn 2? < Which bond is longer, the S bond in S 2 or the Sn bond in Sn 2? Explain. Sn is a longer bond. t is composed of larger atoms, therefore the distance between the nuclei of the bonded atoms will be greater. 4. Which bond angle would you expect to be smaller, S or Sn? Explain. The Sn will be a smaller bond angel. There are two reasons for this. irst, the S bonds are double bonds, so they repel with a greater force and therefore will not be able to be pushed as close together by the lone pair as the single Sn bonds in Sn 2. Second, the Sn bond is polar resulting in the electron density of those bonds being pulled away from the Tin resulting in less repulsion and can therefore be pushed closer together. Sulfur Dioxide (S 2 ) S S Valence Electrons: 18 ybridization: S = sp 2, = sp 2 Electronic Geometry: Trigonal Planar Molecular Geometry: Bent Tin () hloride (Sn 2 ) Sn Sn Valence Electrons: 18 ybridization: S = sp 2, = sp 3 Electronic Geometry: Trigonal Planar Molecular Geometry: Bent

4 AX 4 : 4, N + 4, 3 1. What is the bond angle in 4? What is the N bond angle in N + 4? What is the bond angle in 3? < What is the bond angle in 3? > Which one of these molecules is polar? Using your perspective drawing, draw an arrow toward the more negative side of the molecule. 3 is polar 6. n 3, which bond is longer, or? is a longer bond. This is due to the size of hlorine versus ydrogen Methane ( 4 ), aka arbon tetrahydride Valence Electrons: 8 ybridization: = sp 3 Electronic Geometry: Tetrahedral Molecular Geometry: Tetrahedral Ammonium (N 4 + ) N + N + Valence Electrons: 8 ybridization: N = sp 3 Electronic Geometry: Tetrahedral Molecular Geometry: Tetrahedral Methyl hloride ( 3 ) Valence Electrons: 14 ybridization: = sp 3, = sp 3 Electronic Geometry: Tetrahedral Molecular Geometry: Tetrahedral

5 AX 3 E: N 3, N 3, What is the N bond angle in N 3? < What is the N bond angle in N 3? < What is the bond angle in 3 +? < Would you expect the electron density from the lone pair to be closer to the nitrogen in N 3, or in N 3? Explain. The lone pair will be closer to the nitrogen in N 3. The nitrogen in N 3 is partially positive and will therefore attract the lone pair more than the partially negative Nitrogen in N Which bond angle do you expect to be smaller, N in N 3 or in 3 +? Explain. The N bond angle will be smaller. The luorine atoms attract electron density away from the center atom (N) and therefore repel less. The lone pair on the Nitrogen will push the luorine atoms closer together. Nitrogen Trifluoride (N 3 ) N N Valence Electrons: 26 ybridization: N = sp 3, = sp 3 Electronic Geometry: Tetrahedral Molecular Geometry: Trigonal Pyramidal Ammonia (N 3 ) N N Valence Electrons: 8 ybridization: N = sp 3 Electronic Geometry: Tetrahedral Molecular Geometry: Trigonal Pyramidal ydronium ( 3 + ) + + Valence Electrons: 8 ybridization: = sp 3 Electronic Geometry: Tetrahedral Molecular Geometry: Trigonal Pyramidal

6 AX 2 E 2 : 2, What is the bond angle in 2? < What is the bond angle in 3 3? < What is the bond angle in 3 3? > Do you expect the bond angle to be smaller in 2, or in 3 +? Explain. The bond angle in 2 will be smaller. There are two lone pairs pushing the ydrogen atoms together which will have a greater affect thatn only one lone pair found in 3 +. Water ( 2 ) Valence Electrons: 20 ybridization: = sp 3, Electronic Geometry: Tetrahedral Molecular Geometry: Bent Dimethyl Ether ( 3 3 ) Valence Electrons: 20 ybridization: = sp 3, = sp 3 Electronic Geometry(s): arbon Tetrahedral xygen Tetrahedral Molecular Geometry(s): arbon Tetrahedral xygen Bent

7 AX 5 : P 5, S 4 1. What is the A P A bond angle in P 5? What is the A P E bond angle in P 5? What is the E P E bond angle in P 5? What is the E S bond angle in S 4? > What is the A S bond angle in S 4? > What is the E S E bond angle in S 4? < What is the E S A bond angle in S 4? < s the oxygen in S 4 located in an axial or an equatorial position? Why is this? Equatorial. The equatorial positions allow for more space to minimize repulsion. or this reason, the higher repulsion groups (lone pairs, double bonds) will be placed equatorially. 9. Which bond in S 4 has the shortest bond length? The S= will be the shortest. Double bonds are shorter than single bonds. Phosphorus Pentafluoride (P 5 ) P P Valence Electrons: 40 ybridization: P = sp 3 d, = sp 3 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: Trigonal Bipyramidal Thionyl Tetrafluoride (S 4 ) S S Valence Electrons: 40 ybridization: S = sp 3 d, = sp 3, = sp 2 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: Trigonal Bipyramidal

8 AX 4 E: S 4, What is the A S A bond angle in S 4? The angle will not be 180, greater or less than depends on your point of view. 2. What is the A S E bond angle in S 4? < What is the E S E bond angle in S 4? < What is the A A bond angle in 4 +? The angle will not be 180, greater or less than depends on your point of view. 5. What is the A E bond angle in 4 +? < What is the E E bond angle in 4 +? < Does the lone pair of electrons in S 4 occupy an axial or an equatorial position? Explain. The lone pair will occupy an equatorial position. The equatorial positions allow for more space to minimize repulsion. or this reason, the higher repulsion groups (lone pairs, double bonds) will be placed equatorially Sulfur Tetrafluoride (S 4 ) S S Valence Electrons: 34 ybridization: S = sp 3 d, = sp 3 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: Seesaw odine Tetrafluoride on ( 4 + ) + + Valence Electrons: 34 ybridization: = sp 3 d, = sp 3 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: Seesaw

9 AX 3 E 2 : 3 1. What is the A A bond angle in 3? The angle will not be 180, greater or less than depends on your point of view. 2. What is the A E bond angle in 3? < Why are you not being asked to predict the E E bond angle? There is only one equatorial position occupied, so there is not an E E to be measured. 4. Which bond do you expect to be longer, A or E? Explain. A A E The A bond will be longer. Each of the three bonds is a polar bond. When a bond is polar it shrinks due to an increase in ionic character. Since the two A bonds are roughly 180 from one another, the polarity is cancelled to an extent, and so the bond will shrink less. There is no opposing polar bond for the E so it will be a more polar and therefore shrink more. hlorine Trifluoride ( 3 ) Valence Electrons: 28 ybridization: = sp 3 d, = sp 3 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: T Shaped

10 AX 2 E 3 : 3, 2 1. What is the bond angle in 3? What is the bond angle in 2? Which bond length do you expect to be longer, the bond in 3 or the one in 2? Explain. bond will be longer. t is composed of larger atoms. 4. Why doesn't either fluorine atom in 2 occupy an equatorial position? The equatorial positions allow for more space to minimize repulsion. or this reason, the higher repulsion groups (lone pairs, double bonds) will be placed equatorially. Since this molecule contains three lone pairs, each of the lone pairs will occupy the three equatorial positions. Triiodide on ( 3 ) Valence Electrons: 28 ybridization: (center) = sp 3 d (outer) = sp 3 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: Linear odine Difluoride on ( 2 ) Valence Electrons: 28 ybridization: = sp 3 d, = sp 3 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: Linear

11 AX 6 : S 6, 5 1. What is the 1 S 2 bond angle in S 6? What is the 1 S 3 bond angle in S 6? What is the 1 bond angle in 5? >90 4. What is the 1 2 bond angle in 5? <90 5. What is the 1 5 bond angle in 5? <90 6. What is the 2 5 bond angle in 5? <90 7. Are all of the fluorine atoms in S 6 equivalent? Why? Yes. Each fluorine atom is 90 from four other fluorine atoms and 180 from one other fluorine. 8. Would you expect angles 1 2 and 2 3 in 5 to be equal? Why or why not? Those angles will be equivalent. 1 and 2 are adjacent to one another, and both are adjacent to the double bonded oxygen atom. This is also the case for 2 and 3. or this reason it can be said the bond angles are feeling the same influence. Sulfur exafluoride (S 6 ) S S Valence Electrons: 48 ybridization: S = sp 3 d 2, = sp 3 Electronic Geometry: ctahedral Molecular Geometry: ctahedral odine xide Pentafluoride ( 5 ) Valence Electrons: 48 ybridization: = sp 3 d 2, = sp 2, = sp 3 Electronic Geometry: ctahedral Molecular Geometry: ctahedral

12 AX 5 E: Br 5, Te 5 1. What is the 1 Br 2 bond angle in Br 5? <90 2. What is the 1 Br 3 bond angle in Br 5? All that can be said is the angle will not be 180. To say it is greater than or less than 180 depends on how you view the molecule. f the molecule were viewed from above according to figure 3 below the angle would be <180. f the molecule were viewed from below according to figure 3 below the angle would be > Br 3 Rotate clockwise Br 3 ocus on just 1 Br 2 bond Br < >180 2 igure 1 igure 2 igure 3 3. What is the 1 Br 5 bond angle in Br 5? <90 4. What is the 1 Te 2 bond angle in Te 5? <90 5. What is the 1 Te 3 bond angle in Te 5? All that can be said is the angle will not be 180. To say it is greater than or less than 180 depends on how you view the molecule. f the molecule were viewed from above according to figure 3 below the angle would be <180. f the molecule were viewed from below according to figure 3 below the angle would be > Te 3 5 Rotate clockwise Te 3 ocus on just 1 Br 2 bond Te < >180 2 igure 1 igure 2 igure 3 6. What is the 1 Te 5 bond angle in Te 5? <90

13 7. Which bond in Br 5, Br 1 or Br 5, do you expect to be longer? Explain. The Br 1 bond will be longer than the Br 5. Each bond is a polar bond. When a bond is polar it shrinks due to an increase in ionic character. Since the Br 1 bond has another equivalent bond oriented roughly 180 from it the polarity is cancelled to an extent, and so the bond will shrink less. There is no opposing polar bond for the Br 5 so it will be a more polar and therefore shrink more. 4 5 Br 3 5 Rotate clockwise Br igure 1 2 igure 2 8. Would you expect bond Br 1 in Br 5 to have a bond length that is shorter, longer, or the same as the length of bond Te 1 in Te 5? Explain. The Te 1 will be a longer bond than Br 1. This is due to the size of the Tellurium atom versus the Bromine atom. Bromine Pentafluoride (Br 5 ) Br Br Valence Electrons: 42 ybridization: Br = sp 3 d 2, = sp 3 Electronic Geometry: ctahedral Molecular Geometry: Square Pyramidal Tellurium Pentafluoride on (Te 5 ) Te Te Valence Electrons: 42 ybridization: Te = sp 3 d 2, = sp 3 Electronic Geometry: ctahedral Molecular Geometry: Square Pyramidal

14 AX 4 E 2 : 4 1. What is the 1 2 bond angle in 4? What is the 1 3 bond angle in 4? Why are the two lone pairs 4 on opposite vertices of the molecule? The lone pairs require more space since they repel more than bonded pairs. or this reason the two lone pairs will be as far from one another as possible to minimize repulsion. 4. Would you expect 1 to have a shorter, longer, or the same bond length as 2? Explain. The bonds will be the same length. The positions of the chlorine atoms ( 1 and 2 ) are equivalent to one another. odine Tetrachloride on ( 4 ) Valence Electrons: 42 ybridization: = sp 3 d 2, = sp 3 Electronic Geometry: ctahedral Molecular Geometry: Square Planar