Predicting electron-pair geometry and molecular structure: xef
4
Of all the noble gases, xenon is the most reactive, frequently reacting with elements such as oxygen and fluorine. Predict the electron-pair geometry and molecular structure of the XeF
4 molecule.
Solution
The Lewis structure of XeF
4 indicates six regions of high electron density around the xenon atom: two lone pairs and four bonds:
These six regions adopt an octahedral arrangement (
[link] ), which is the electron-pair geometry. To minimize repulsions, the lone pairs should be on opposite sides of the central atom (
[link] ). The five atoms are all in the same plane and have a square planar molecular structure.
(a) XeF
4 adopts an octahedral arrangement with two lone pairs (red lines) and four bonds in the electron-pair geometry. (b) The molecular structure is square planar with the lone pairs directly across from one another.
Check your learning
In a certain molecule, the central atom has three lone pairs and two bonds. What will the electron pair geometry and molecular structure be?
Answer:
electron pair geometry: trigonal bipyramidal; molecular structure: linear
When a molecule or polyatomic ion has only one central atom, the molecular structure completely describes the shape of the molecule. Larger molecules do not have a single central atom, but are connected by a chain of interior atoms that each possess a “local” geometry. The way these local structures are oriented with respect to each other also influences the molecular shape, but such considerations are largely beyond the scope of this introductory discussion. For our purposes, we will only focus on determining the local structures.
Predicting structure in multicenter molecules
The Lewis structure for the simplest amino acid, glycine, H
2 NCH
2 CO
2 H, is shown here. Predict the local geometry for the nitrogen atom, the two carbon atoms, and the oxygen atom with a hydrogen atom attached:
Solution
Consider each central atom independently. The electron-pair geometries:
nitrogen––four regions of electron density; tetrahedral
carbon (
C H
2 )––four regions of electron density; tetrahedral
carbon (
C O
2 )—three regions of electron density; trigonal planar
oxygen (
O H)—four regions of electron density; tetrahedral
The local structures:
nitrogen––three bonds, one lone pair; trigonal pyramidal
carbon (
C H
2 )—four bonds, no lone pairs; tetrahedral
carbon (
C O
2 )—three bonds (double bond counts as one bond), no lone pairs; trigonal planar
oxygen (
O H)—two bonds, two lone pairs; bent (109°)
Check your learning
Another amino acid is alanine, which has the Lewis structure shown here. Predict the electron-pair geometry and local structure of the nitrogen atom, the three carbon atoms, and the oxygen atom with hydrogen attached:
Answer:
electron-pair geometries: nitrogen––tetrahedral; carbon (
C H)—tetrahedral; carbon (
C H
3 )—tetrahedral; carbon (
C O
2 )—trigonal planar; oxygen (
O H)—tetrahedral; local structures: nitrogen—trigonal pyramidal; carbon (
C H)—tetrahedral; carbon (
C H
3 )—tetrahedral; carbon (
C O
2 )—trigonal planar; oxygen (
O H)—bent (109°)
A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
