Shapes Of Molecules

Question 1

What does the shape of a molecule depend on?

Answer 1

The charge clouds that are moving around a central nucleus

Question 2

What is a charge cloud?

Answer 2

An area where you have a large chance of finding an electron

Question 3

Pairs/clouds of electrons repel eachother…

Answer 3

Until they are as far apart as possible in a 3D space

Question 4

The electrons repelling each other until they are as far apart as possible does what?

Answer 4

Keeps repulsion at a minimum so that they are the most stable

Question 5

What does a “stick” represent when drawing molecules?

Answer 5

Both atoms and the bond are in the same plane

Question 6

What does a solid wedge mean when drawing a 3D molecule?

Answer 6

The bond is coming out towards us

Question 7

What does the dotted/broken line represent when drawing a 3D molecule?

Answer 7

The bond is going into the paper- the bond is moving away from us

Question 8

AB2?

Answer 8

B-A-B (as far apart as possible)
Linear
180 degrees
2 charge clouds

Question 9

AB3?

Answer 9

3 charge clouds
120 degrees
Trigonal planar (flat triangle)

Question 10

AB4?

Answer 10

4 charge clouds
109.5 degrees
Tetrahedral shape

Question 11

AB5?

Answer 11

5 charge clouds
Trigonal bipyramid
90 degrees
120 degrees

Question 12

AB6?

Answer 12

6 electron clouds
Octahedral
90 degrees

Question 13

Examples: BeCl2?

Answer 13

Linear
180 degrees

Question 14

Examples: BF3?

Answer 14

Trigonal planer
120 degrees

Question 15

Examples: CH4?

Answer 15

Tetrahedral
109.5 degrees

Question 16

PCl5?

Answer 16

120 degrees
90 degrees
Triganol bypyramid

Question 17

SF6?

Answer 17

90 degrees
Octahedral

Question 18

What are lone pairs of electrons?

Answer 18

Electrons in the outer shall that aren’t involved in bonding

Question 19

Do lone pairs of electrons repel the bonding pairs of electrons further apart or closer together?

Answer 19

Closer together

Question 20

For each lone pair, how much is the bond angle reduced by?

Answer 20

2.5 degrees for each lone pair

Question 21

Example: ammonia?

Answer 21

Four charge clouds
3 bonding pairs and one lone pair
107
Pyramidal

Question 22

Example: water?

Answer 22

4 charge clouds
2 bonding pairs and 2 lone pairs
104.5 degrees
Bent

Question 23

How to work out shapes?

Answer 23

1) figure out which group the central atom is in so then we can figure out the number of valence electrons
2) how many atoms are bonded to the central atom?
3) overall charge of the molecule?- if negative need to add electron, if positive need to remove electron
4) calculate the total number of electrons then divide by 2 to figure out how many electron pairs there are
5) compare to bonded atoms to check for lone pairs