The Shapes of Molecules

Question: Consider the following molecular shapes:

1. Match each shape with one of the following species: ${\mathbf{XeF}}_{\mathbf{3}}^{\mathbf{+}}$,${\mathbf{SbBr}}_{\mathbf{3}}^{}$, ${\mathbf{GaCl}}_{\mathbf{3}}^{}$.
2. Which, if any, is polar?
3. Which has the most valence electrons around the central atom?

Draw the Lewis structure with the lowest formal charges, and determine the charge of each atom in 

(a)  ${{\mathbf{BF}}_4}^{-}$

(b)  $\mathbf{\text{ClNO}}$

Draw a Lewis structure for a resonance form of each ion with the lowest possible formal charges, show the charges, and give oxidation numbers of the atoms:

(a)  ${{\mathbf{AsO}}_4}^{3-}$

(b)  ${{\mathbf{ClO}}_2}^{-}$

Draw the Lewis structure with lowest formal charges, and determine the charge of each atom in

(a) OCS

(b) NO.

Draw Lewis structures of all the important resonance forms of (a)  ${{\mathbf{HCO}}_2}^{-}$ (H is attached to C); (b)  ${\mathbf{HBrO}}_4\left({\mathbf{HOBrO}}_3\right)$

Which of these atoms cannot serve as a central atom in a Lewis structure?

1. O;
2. He;
3. F;
4. H; 
5. P?

Explain.

In which of these bonding patterns does X obey the octet rule?

What is required for an atom to expand its valence shell?

Which of the following atoms can expand its valence shell: F, S, H, Al, Se, Cl?

Draw a Lewis structure for (a) ${\mathbf{SiF}}_4$ ; (b) ${\mathbf{SeCl}}_2$ ; (c)  ${\mathbf{COF}}_2$ (C is central).

Draw a Lewis structure for

(a) ${{\mathbf{PH}}_4}^{+}$ ; 

(b)  ${\mathbf{C}}_2{\mathbf{F}}_4$; 

(c) ${\mathbf{SbH}}_3$.

Draw a Lewis structure for (a)  ${\mathbf{PF}}_3$; (b) ${\mathbf{H}}_2{\mathbf{CO}}_3$  (both H atoms are attached to O atoms); (c)  ${\mathbf{CS}}_2$.

Draw a Lewis structure for (a) ${\mathbf{CH}}_4\mathbf{S}$ ; (b) ${\mathbf{S}}_2{\mathbf{Cl}}_2$ ; (c) ${\mathbf{CHCl}}_3$ .

Draw the Lewis structure with the lowest formal charges, and determine the charge of each atom in

(a)  ${\mathbf{IF}}_5$

(b)  ${{\mathbf{AlH}}_4}^{-}$

Draw the Lewis structure with lowest formal charges, and determine the charge of each atom in

(a)  ${\mathbf{CN}}^{-}$

(b)  ${\mathbf{ClO}}^{-}$

Draw Lewis structures of all the important resonance forms of

(a)  ${{\mathbf{N}}_3}^{-}$

(b)  ${{\mathbf{NO}}_2}^{-}$

Draw Lewis structures of all the important resonance forms of

(a)  ${{\mathbf{NO}}_2}^{+}$

(b)  ${\mathbf{NO}}_2\mathbf{F}$ (N is central)

Draw Lewis structures of all the important resonance forms of

(a)  ${\mathbf{HNO}}_3\left({\mathbf{HONO}}_2\right)$

(b)  ${{\mathbf{HAsO}}_4}^{2-}\left({{\mathbf{HOAsO}}_3}^{2-}\right)$

When is a resonance hybrid needed to adequately depict the bonding in a molecule? Using  ${\mathbf{NO}}_{\mathbf{2}}$ as an example, explain how a resonance hybrid is consistent with the actual bond length, bond strength, and bond order.

Which of the following numbers of electron groups can give rise to a bent (V-shaped) molecule: two, three, four, five, six? Draw an example for each case, showing the shape classification (AXmEn) and the ideal bond angle.

Name all the molecular shapes that have a tetrahedral electron-group arrangement.

What would you expect to be the electron-group arrangement around atom A in each of the following cases? For each arrangement, give the ideal bond angle and the direction of any expected deviation:

Determine the electron-group arrangement, molecular shape, and ideal bond angle(s) for each of the following: (a) ${\mathbf{O}}_3$ (b) ${\mathbf{H}}_3{\mathbf{O}}^{+}$ (c)  ${\mathbf{NF}}_3$

Determine the electron-group arrangement, molecular shape, and ideal bond angle(s) for each of the following:

(a)  ${\mathbf{SO}}_4^{2-}$

(b)  ${\mathbf{NO}}_2^{-}$

(c)  ${\mathbf{PH}}_3$

Determine the electron-group arrangement, molecular shape, and ideal bond angle(s) for each of the following:

(a)  ${\mathbf{CO}}_3^{2-}$

(b)  ${\mathbf{SO}}_2$

(c)  ${\mathbf{CF}}_4$

Determine the electron-group arrangement, molecular shape, and ideal bond angle(s) for each of the following: (a) ${\mathbf{SO}}_3$  (b)  ${\mathbf{N}}_2\mathbf{O}$  (N is central) (c)  ${\mathbf{CH}}_2{\mathbf{Cl}}_2$ .

Name the shape and give the ${\mathbf{AX}}_m{\mathbf{E}}_n$  classification and ideal bond angle(s) for each of the following general molecules:

(a) 

(b) 

(c) 

Name the shape and give the ${\mathbf{AX}}_m{\mathbf{E}}_n$  classification and ideal bond angle(s) for each of the following general molecules:

 (a) 

 (b)   

 (c)  

These species do not obey the octet rule. Draw a Lewis structure for each, and state the type of octet-rule exception: 

(a) ${\mathbf{BH}}_3$

(b) ${{\mathbf{AsF}}_4}^{-}$

(c)  ${\mathbf{SeCl}}_{\mathbf{4}}$

These species do not obey the octet rule. Draw a Lewis structure for each, and state the type of octet-rule exception: 

(a) ${{\mathbf{PF}}_6}^{-}$

(b)  ${\mathbf{ClO}}_3$

(c)  ${\mathbf{H}}_3{\mathbf{PO}}_3$ (one P±H bond)

These species do not obey the octet rule. Draw a Lewis structure for each, and state the type of octet-rule exception: 

(a) ${\mathbf{BrF}}_3$

(b) ${{\mathbf{ICl}}_2}^{-}$

(c) ${\mathbf{BeF}}_2$

These species do not obey the octet rule. Draw a Lewis structure for each, and state the type of octet-rule exception: 

(a) ${{\mathbf{O}}_3}^{-}$

(b) ${\mathbf{XeF}}_2$

(c) ${\mathbf{SbF}}_4$

Molten beryllium chloride reacts with chloride ion from molten  $\mathbf{NaCl}$ to form the ${{\mathbf{BeCl}}_4}^{2-}$ ion, in which the Be atom attains an octet. Show the net ionic reaction with Lewis structures

Despite many attempts, the per-bromate ion ( ${\mathbf{BrO}}_4$ ) was not prepared in the laboratory until about 1970. (In fact, articles were published explaining theoretically why it could never be prepared!) Draw a Lewis structure for ${{\mathbf{BrO}}_4}^{-}$ which all atoms have the lowest formal charges.

Cryolite ( ${\mathbf{Na}}_3{\mathbf{AlF}}_6$) is an indispensable component in the electrochemical manufacture of aluminium. Draw a Lewis structure for the ${{\mathbf{AlF}}_6}^{3-}$ ion.

Phosgene is a colorless, highly toxic gas employed against troops in World War I and used today as a key reactant in organic syntheses. From the following resonance structures, select the one with the lowest formal charges:

If you know the formula of a molecule or ion, what is the first step in predicting its shape?

In what situation is the name of the molecular shape the same as the name of the electron-group arrangement?

Consider the following molecular shapes.

a.Which has the most electron pairs (both bonding and lone pairs) around the central atom?

b.Which has the most lone pairs around the central atom?

c.Do any have only bonding pairs around the central atom? A B C

Question: Draw a Lewis structure for a resonance form of each ion with the lowest possible formal charges, show the charges, and give oxidation numbers of the atoms: 

a)  BrO₃

b)  SO₃ ^2-.

Determine the shape around each central atom in each molecule, and explain any deviation from ideal bond angles: (a) ${\mathbf{H}}_2^{}{\mathbf{SO}}_3$  (no H-S bond) (b) ${\mathbf{N}}_2^{}{\mathbf{O}}_3$  (ONNO₂)

In the gas phase, phosphorous pentachloride exists as separate molecules. In the solid phase, however, the compound is composed of alternating ${{\mathbf{PCl}}_4}^{+}$  and ${{\mathbf{PCl}}_6}^{-}$ ions. What change(s) in molecular shape occur(s) as  ${\mathbf{PCl}}_{\mathbf{5}}$ solidifies? How does the Cl-P-Cl angle change?

Determine the shape, ideal bond angle(s), and the direction of any deviation from those angles for each of the following:

(a)  ${\mathbf{ClO}}_2^{-}$

(b)  ${\mathbf{PCl}}_5$

(c)  ${\mathbf{SeF}}_4$

(d)  ${\mathbf{KrF}}_4$

Determine the shape, ideal bond angle(s), and the direction of any deviation from those angles for each of the following:

(a)  ${{\mathbf{ClO}}_3}^{-}$

(b)  ${{\mathbf{IF}}_4}^{-}$

(c)  ${\mathbf{SeOF}}_2$

(d)  ${{\mathbf{TeF}}_5}^{-}$

Determine the shape around each central atom in each molecule, and explain any deviation from ideal bond angles: (a) ${\mathbf{CH}}_3{\mathbf{OH}}_{}$  (b)   ${\mathbf{N}}_2{\mathbf{O}}_4\mathbf{\left(}{\mathbf{O}}_2{\mathbf{NNO}}_2\mathbf{\right)}$

Determine the shape around each central atom in each molecule, and explain any deviation from ideal bond angles: (a) ${\mathbf{H}}_3{\mathbf{PO}}_4$  (no H-P bond) (b)  ${\mathbf{CH}}_3{\mathbf{OCH}}_2{\mathbf{CH}}_3$

Determine the shape around each central atom in each molecule, and explain any deviation from ideal bond angles: (a) ${\mathbf{CH}}_3\mathbf{COOH}$  (b)  ${\mathbf{H}}_2{\mathbf{O}}_2$

Which molecule in each pair has the greater dipole moment? Give the reason for your choice.

1. ${\mathbf{ClO}}_2\mathbf{or}{\mathbf{SO}}_2$
   
2. HBr or HCl
3. ${\mathbf{BeCl}}_2\mathbf{or}{\mathbf{SCl}}_2$
   
4. ${\mathbf{AsF}}_3\mathbf{or}{\mathbf{AsF}}_5$
   

Arrange the following AF_n species in order of increasing F-A-F bond angles:  ${\mathbf{BF}}_3$ , ${\mathbf{BeF}}_2$  ,  ${\mathbf{CF}}_4\mathbf{,}{\mathbf{NF}}_3\mathbf{,}{\mathbf{OF}}_2^{-}$. 

Arrange the following ACl_n species in order of decreasing Cl-A-Cl bond angles:  ${\mathbf{SCl}}_2$ , data-custom-editor="chemistry" ${\mathbf{OCl}}_2$ ,  ${\mathbf{PCl}}_3$ , ${\mathbf{SiCl}}_4$  , data-custom-editor="chemistry" ${{\mathbf{SiCl}}_6}^{2-}$  

State an ideal value for each of the bond angles in each molecule, and note where you expect deviations: 

(a) 

 b. 

c.