Shapes of Molecules

Question 1

What are charge clouds?

Answer 1

Bonding and lone e- pairs exist as them.
A charge cloud is an area where you have a high chance of finding a 2e-.
e- don’t stay still - they whizz around within the charge cloud

Question 2

Valence-Shell Electron-Pair Repulsion Theory

Answer 2

E- are -vely charged => charge clouds repel each other as much as possible => 2e- remain far from each other as possible
lone pair charge clouds repel more than bonding pair charge clouds => greatest angles between lone 2e- and bond angles between bonding 2e- are often reduced as pushed together by lone pair repulsion

Question 3

Angles according to VSEPRT

Answer 3

lone pair/lone pair angle => biggest
lone pair/bonding pair angle
bonding pair/bonding pair angle => smallest

Question 4

Steps to molecule shape prediction

Answer 4

1) Find central atom
2) Work out no. e- in outer shell
3) draw simple dot and cross diagram
4) add/ take away e- if instructed by ion
5) count number of e- pairs
6) translate into a known shape!!

Question 5

Shape with 2 electron pairs

Answer 5

No lone pairs - linear

Bond angle = 180

Question 6

Shape with 3 electron pairs

Answer 6

No lone pairs - trigonal planar

Bond angle = 120

Question 7

Shape with 4 electron pairs

Answer 7

No lone pairs - Tetrahedral
Bond angle = 109.5

1 lone pair - trigonal pyramidal
Bond angle = 107

2 lone pairs - bent
Bond angle = 104.5

Question 8

Shape with 5 electron pairs

Answer 8

No lone pairs - trigonal bipyramidal
Bond angle = 120, 90

1 lone pair - seesaw
Bond angle = 102, 87, 90

2 lone pairs - T Shaped
Bond Angle = 88

Question 9

Shape with 6 electron pairs

Answer 9

No lone pairs - Octahedral
Bond angle = 90

2 lone pairs - Square planar
Bond angle = 90