Shapes Of Molecules And Ions

Question 1

What is electron pair repulsion theory?

Answer 1

The shape depends on the number of electron pairs around the central atom
Electron pairs repel each other so stay as far away as possible

Question 2

What is the shape with 4 bond pairs called and what is the bond angle?

Answer 2

109.5

Tetrahedral

Question 3

What is the shape with 5 bond pairs called and what is the bond angle?

Answer 3

120, 90

Trigonial bipyramidal

Question 4

What is the shape with 6 bond pairs called and what is the bond angle?

Answer 4

90

Octahedral

Question 5

What is the shape with 3 bond pairs called and what is the bond angle?

Answer 5

120

Trigonial planar

Question 6

What is the shape with 2 bond pairs called and what is the bond angle?

Answer 6

180

Linear

Question 7

How does the repulsing between lone pairs and bonding pairs vary?

Answer 7

Greater as the electron pair is closer to the nucleus, reducing the bond angle by 2.5° each time

Question 8

What is the structure of an ionic compound?

Answer 8

The arrangement of ions in the lattice which maximises the attractive forces between oppositely charged ions and minimises repulsive forces
They attract opposite be charged ions in all directions and therefore repel them similarly

Question 9

What are allotropes?

Answer 9

Different forms of the same element that exist in the same physical state. This depends on the bonding between the atoms

Question 10

What is the structure of diamond?

Answer 10

Interlocking tetrahedral carbon atoms, each covalently bonded to 4 others in a giant molecule

Question 11

What is the structure of graphite?

Answer 11

Planes of trigonal carbon atoms, each bonded to 3 other atoms at 120°
These planes are arranged in sheets to phone 3-D crystals, held together by weak intermolecular forces between the layers

Question 12

Why can carbon conduct electricity?

Answer 12

Each atom has only three covalent bonds so the remaining outershell electrons is free to circulate within each plane of the atoms

Question 13

What is the most reactive form of carbon?

Answer 13

Amorphous

Burns quite easily in there and attacked by strong oxidising agents

Question 14

What does the properties of amorphous carbon depend on?

Answer 14

It’s method of manufacture and the conditions it is later subjected to

Question 15

Where can amorphous carbon be found?

Answer 15

Naturally in coal and soot
Can be obtained by heating organic compounds to very high temperatures in the absence of their burning organic papers with insufficient oxygen

Question 16

What is the structure of the fullerene?

Answer 16

It is in allotropes of carbon where they are linked in and almost spherical model
It has delocalised electrons so it can conduct electricity

Question 17

What are nano tubes?

Answer 17

Closed – cage carbon structures that contain 12 five members rings and almost any number of six-member the rings

Question 18

What are the possible uses for nano tubes?

Answer 18

Aircraft, space and the car industries

Superconducting and have a normal strength and great lightness