Chemical bonds and structure—>properties

Question 1

How do particles move in a solid

Answer 1

They vibrate

Question 2

How do particles move in a liquid

Answer 2

They slide over each other in a changing/random arrangement

Question 3

Why do some ionic solids dissolve in water

Answer 3

Water molecules can split up lattice

Question 4

How are ions held together in ionic bonding

Answer 4

.Ionic bonds act in all directions + attract oppositely charged ions
.Giant structure/lattice formed

Question 5

How do particles move in a gas and how does it cause pressure

Answer 5

1. They move very quickly in all directions

2. They bash against walls of their container which exerts a force which causes pressure

Question 6

What, in terms of particles, happens when a solid melts

Answer 6

1. Particles vibrate faster as temp increases
2. Enough energy transferred to solid for forces between particles to break
3. Particles break away from fixed positions —> liquid

Question 7

What, in terms of particles, happens when a liquid evaporates

Answer 7

1. Particles move faster as temp increases
2. Some particles escape from surface before boiling point reached
3. Bubbles form in liquid + rise to surface

Question 8

Why do ionic compounds have high melting/boiling points

Answer 8

.Large structures —>many electrostatic forces—>lots of energy required to overcome ionic bonds to melt solids

EVERY IONIC STRUCTURE IS SOLID AT ROOM TEMP

Question 9

A) Why is the particle model limiting

B) How can particles vary

Answer 9

A) Assumes particles = solid spheres (which they are neither of) with no forces between
B)
-in size
-can be atoms, molecules or ions
-Some can contain many atoms

Question 10

When will intermolecular forces give the molecule a higher melting point

Answer 10

When the molecule is larger because the force will be higher

Question 11

What does ionic bonding effectively bond together

Answer 11

Oppositely charged ions

Question 12

Why can ionic compounds only conduct when molten or dissolved

Answer 12

Ions are free to move so can carry charge

NO ELECTRONS

Question 13

What is the limit of most models (3)

Answer 13

.Don’t show actual shape of molecule
.Electrons aren’t shown to be constantly moving
.Don’t show all electrons identically

Question 14

What force separates neighbouring molecules and how does it affect the attraction between them

Answer 14

Intermolecular forces and they give simple molecules little attraction for each other

Question 15

What is a polymer

Answer 15

A substance consisting of many small molecules covalently bonding to form long chains

Question 16

Why are polymers solid at room temperature

Answer 16

They have strong intermolecular forces because they are large molecules

Question 17

Where does metallic bonding occur

Answer 17

In metallic elements and alloys

Question 18

What happens during metallic bonding

Answer 18

1) No electrons physically leave structure
2) electrons can move throughout metal making atoms into ions
3)

Question 19

Why do metals have high melting and boiling points

Answer 19

Electrostatic forces between atoms and delocalised electrons

Question 20

What is the empirical formula of 60g magnesium and 40g oxygen

Answer 20

60/24=2.5 moles
40/16=2.5 moles
1:1
MgO

Question 21

How do you draw a repeating unit of poly(ethene)

Answer 21

/H H\
( C - C )
\H H/ n

n = large number

Question 22

How are the electrons in an electronic structure able to move throughout it

Answer 22

The electrons in the outer shell of metal atoms are delocalised

Question 23

Why do small molecules not conduct electricity

Answer 23

The molecules don’t have an overall charge

Question 24

How are atoms arranged in metals

Answer 24

In layers

Question 25

Why are alloys harder than pure metals

Answer 25

The bigger or smaller atoms from the other pure metal distorts the layers of the other pure metals
I
L __ greater force for layers to slide over each other

Question 26

Why are metals good thermal conductors

Answer 26

Because energy is transferred by the delocalised electrons