C3

Question 1

particles in a solid

Answer 1

packed closely together and vibrate around fixed positions. cannot be compressed

Question 2

particles in a liquid

Answer 2

close together but can slip over each other in random motion.

Question 3

particles in a gas

Answer 3

lots of space between them and move around randomly

Question 4

melting and boiling

Answer 4

energy is transferred from the surroundings to the substance

Question 5

freezing and condensing

Answer 5

energy is transferred from the substance to the surroundings

Question 6

particle model

Answer 6

The simple particle model is useful when comparing properties, but has limitations because the atoms, molecules and ions that make up substances are not solid spheres with no force between them.

Question 7

forming compounds

Answer 7

elements react together to form compounds by gaining or losing electrons

Question 8

losing electrons to form positive ions

Answer 8

In ionic bonding atoms lose or gain electrons to form charged particles called ions

Question 9

gaining electrons to form negative ions

Answer 9

when non metals react with metals, the non metal atoms gain electrons to achieve the stable electronic structure of a noble gas.

Question 10

representing ionic bonding

Answer 10

metal atoms that lose electrons react with non metal atoms which tend to gain electrons

Question 11

ionic bonding

Answer 11

Ionic compounds are held together by very string forces of attraction between their oppositely charged ions. This is called ionic bonding

The ionic bonds between the charged particles result in an arrangement of ions called a giant structure or giant lattice.

Question 12

giant ionic lattice

Answer 12

• It takes a lot of energy to break the many strong ionic bonds, operating in all different directions, that hold a giant ionic lattice together.
• Ionic compounds have high m.p
• all solids at room temp

Question 13

do ionic compounds conduct electricity?

Answer 13

• ionic compounds conduct electricity when molten or dissolved in water, because their ions become mobile and carry charge

Question 14

covalent bonding

Answer 14

• covalent bonds are formed when atoms of non-metals share pairs of electrons with each other
• The atoms of non-metals tend to gain electrons to get stable electron structures
• Each shared pair of electrons is a covalent bond

Question 15

simple molecules

Answer 15

• substances made of simple molecules have low m.p and b.p
• forces between simple molecules are weak, which is why they have low m.p and b.p
• they have no overall charge, so they cant carry electrical charge and dont conduct electricity

Question 16

models

Answer 16

used to help understand bonding but each model has limitations

Question 17

giant covalent structures

Answer 17

• all atoms are bonded to each other by strong covalent bonds
• have high m.p and b.p as lots of energy is needed to break the covalent bonds between the atoms
• dont contain charged particles, so dont conduct electricity

Question 18

diamond

Answer 18

• giant covalent structure
• made up of carbon atoms that each form four covalent bonds
• really hard
• strong covalent bonds need lots of energy to break
• doesn’t conduct electricity because no free electrons

Question 19

Graphite

Answer 19

• each carbon atom forms three covalent bonds, creating sheets of carbon atoms in hexagons
• no covalent bonds between the layers , so held together weakly so they can move over each other
• good lubricating material
• high m.p so needs lots of energy to break covalent bonds
• delocalised electrons, so charge can move freely and conducts electricity

Question 20

Graphene

Answer 20

• sheet of carbon atoms in hexagons
• one atom thick
• strong network of covalent bonds
• light so added to composite materials improving strength without adding much weight
• delocalised electrons, so conducts electricity

Question 21

Fullerenes

Answer 21

• molecules of carbon
• form nanotubes
• conduct electric and thermal energy
• high tensile strength
• strengthens materials without adding weight

Question 22

Fullerene uses

Answer 22

• used to cage other molecules, so forms around another atom or molecule which is then trapped inside. This could deliver a drug into the body
• huge surface area, so make good industrial catalysts
• good lubricants

Question 23

Metal atoms

Answer 23

• atoms in metals are closely packed together and arranged in layers

Question 24

metallic bonding

Answer 24

positively charged metal ions, which are held together by electrons from the outermost shell of each metal atom. These delocalised electrons are free to move throughout the giant metallic lattice.

Question 25

giant metallic structures

Answer 25

- metals can be bent and shaped because the layers of atoms in a giant metallic structure can slide over each other - alloys are harder than pure metals because the layers in a pure metal are distorted by atoms of different sizes in an alloy - delocalised electrons in metals enable electricity and thermal energy to be transferred through metal easily

Question 26

nanoparticles

Answer 26

- nanoscience is the study of small particles that are between 1-100 nanometres in size - nanoparticles have properties different from those for the same materials in bulk - they have high surface area to volume ratio - high percentage of their atoms exposed at their surface - catalysts needed for industrial processes