2.2.2 Shapes of Molecules and Ions

Question 1

what is the bond angle of a trigonal planar molecule

Answer 1

120 degrees

Question 2

what is the bond angle of a tetrahedral molecule

Answer 2

109.5 degrees

Question 3

what is the bond angle of an octahedral molecule

Answer 3

90 degrees

Question 4

what is the bond angle of a pyramidal molecule

Answer 4

107 degrees

Question 5

what is the bond angle of a non-linear molecule

Answer 5

104.5 degrees

Question 6

what is the bond angle of a linear molecule

Answer 6

180 degrees

Question 7

how many bonded and lone pairs of electrons are in a trigonal planar molecule

Answer 7

3 bonded pairs and 0 lone pairs

Question 8

how many bonded and lone pairs of electrons are in a tetrahedral molecule

Answer 8

4 bonded pairs and 0 lone pairs

Question 9

how many bonded and lone pairs of electrons are in a octahedral molecule

Answer 9

6 bonded pairs and 0 lone pairs

Question 10

how many bonded and lone pairs of electrons are in a pyramidal molecule

Answer 10

3 bonded pairs and 1 lone pair

Question 11

how many bonded and lone pairs of electrons are in a non-linear molecule

Answer 11

2 bonded pairs and 2 lone pairs

Question 12

how many bonded and lone pairs of electrons are in a linear molecule

Answer 12

4 bonded pairs and 0 lone pairs

Question 13

Explain the molecular shape of NH3

Answer 13

• Bonding pairs: 3
• lone pairs: 1
• 3D structure: lone pair of electrons on top of the N, 3 H’s connected 1 via a line, the other via a triangle pointing to the N and the last by dahed vertical lines.
• shape name: pyramidal
• Bond angle: 107

Question 14

Explain how are the shapes of molecules are determined

Answer 14

The shape is determined by the number of bonded pairs of electrons and the number of lone pairs of electrons (on the central atom).
This is because electrons are negitively charged so repel each other.
Lone pairs of electrons repel slightly more than bonding pairs, because of this they reduce the bond angle in a molecule.

Question 15

explain the molecular shape of BF3

Answer 15

• Bonding pairs: 3
• lone pairs: 0
• 3D structure: B with 3 F’s connected by lines at a slant.
• shape name: Trigonal planer
• Bond angle: 120

Question 16

Explain the molecular shape of CH4

Answer 16

• Bonding pairs: 4
• lone pairs: 0
• 3D structure: C with 4 H’s 2 are connected by lines, 1 is connected by a triangle pointing towards the C and the 4th is connected by dashed vertical lines
• shape name: Tetrahedral
• Bond angle: 109.5

Question 17

Explain the molecular shape of SF6

Answer 17

• Bonding pairs: 6
• lone pairs: 0
• 3D structure: S with 6 F’s, 2 F’s (top and bottom) are connected to the S with straight lines, 2 more are connected by thin triangles pointing to the S and the last 2 are connected by the dashed vertical lines
• shape name: Octahedral
• Bond angle: 90

Question 18

Explain the molecular shape of H2O

Answer 18

• Bonding pairs: 2
• lone pairs: 2
• 3D structure: O with 2 lines each connecting to a H and has 2 lone pairs of electrons on top each slightly to the side
• shape name: Non-linear
• Bond angle: 104.5

Question 19

Explain the molecular shape of CO2

Answer 19

• Bonding pairs: 4
• lone pairs: 0
• 3D structure: O is connected to a C by a double bond (long equals sign) which is connected to an O with another double bond in a straight line
• shape name: linear
• Bond angle: 180

Question 20

What are the names of the molecules

Answer 20

• linear
• trigonal planar
• tetrahedral
• pyramidal
• non-linear
• octahedral