C2: Structure, Bonding and Properties of materials

Question 1

Ionic bonding(8):

Answer 1

• particles are oppositely charged ions
• occurs in compounds formed from metals combined with non metals
• high melting and boiling points (large amount of energy needed to break the bonds)
• DO NOT conduct electricity when solid ( ions are held in a fixed position in the lattice so they cannot move)
• DO conduct electricity when molten or dissolved (the lattice breaks apart and the ions are free to move)

Question 2

Covalent bonds(4):

Answer 2

• particles are atoms that share pairs of electrons
• occurs in most non metallic elements and compounds of non metals
• can be small molecules e.g. ammonia
• can be giant covalent structures e.g. polymers

Question 3

Metallic bonding(4):

Answer 3

• particles are atoms which share delocalised electrons
• occurs in metallic elements and alloys
• giant structure of atoms arranged in a regular pattern
• electrons in the outer shell of metal atoms are delocalised and free to move through the whole structure, this sharing of electrons leads to strong metallic bonds

Question 4

What is an alloy?

Answer 4

A mixture of two or more elements at least one of which is a metal

Question 5

Properties of alloys(2):

Answer 5

• harder than a pure metal because atoms of different sizes disrupt the layers so they cannot slide over each other
• high melting points due to strong metallic bonds

Question 6

Metals as conductors(2):

Answer 6

• good conductors of electricity as they have delocalised electrons which carry electrical charge through the metal
• good conductors of thermal energy because energy is transferred by the delocalised electrons

Question 7

State changes(3):

Answer 7

• Melting and freezing happen at the melting point
• boiling and condensing happen at the boiling point
• the amount of energy needed for a state change depends on the strength of forces between the particles in the substance

Question 8

Ionic bonding in metals(2):

Answer 8

• Metal atoms loose electrons and become positively charged ions;
• group 1 metals form + 1 ions
• group 2 metals form +2 ions

Question 9

Ionic bonding in non metals(3):

Answer 9

• non metal atoms gain electrons to become negatively charged ions
• group 6 non metals form -2 ions
• group 7 non metals form - 1 ions

Question 10

Graphene(5):

Answer 10

• excellent conductor
• very strong
• a single layer of graphite is one atom thick
• contains delocalized electrons
• contains strong covalent bonds

Question 11

Allotropes of carbon/ giant covalent structures(5):

Answer 11

• diamond, graphite and silicon dioxide
• very high melting points
• lots of energy needed to break their strong, covalent bonds

Question 12

Properties of small molecules(6):

Answer 12

• covalent bonds in the molecule are strong but forces between molecules are weak
• LOW melting and boiling points(due to having weak intermolecular forces that are easily broken)
• DO NOT conduct electricity (due to them not having an overall electrical charge)

Question 13

Properties of a polymer(4):

Answer 13

A polymer is a large molecule formed when lots of smaller monomer molecules join together

• solids at room temperature
• atoms are linked by strong covalent bonds
• high melting and boiling points

Question 14

Diamond(7):

Answer 14

• each carbon atom is bonded to 3 others
• very hard
• high melting point
• DOES NOT conduct electricity
• rigid structure
• strong covalent bonds
• no delocalized electrons

Question 15

Graphite/ layers of graphene(7):

Answer 15

• each carbon atom is bonded to three others, forming hexagonal rings with no covalent bonds between layers
• slippery
• very high melting point
• DOES conduct electricity
• layers can slide over each other
• strong covalent bonds
• delocalized electrons between layers

Question 16

Fullerenes:

Answer 16

• hexagonal rings of carbon atoms with hollow shapes

Question 17

Carbon nanotubes(7):

Answer 17

• very thin and long, cylindrical fullerenes
• very conductive
• high tensile strength
• large surface area to volume ratio
• used in the electronics industry
• reinforces composite materials
• work as catalysts and lubricants

Question 18

Nanoparticles(8):

Answer 18

• between 1 and 100 nanometers(nm) in size ( 1 nanometer = 1x 10to the power of 9)
• uses; healthcare, cosmetics, sun cream, catalysts, deodorants and electronics
• nanoparticles May be toxic to people, they may also cause harm if they enter the brain or blood stream

Question 19

Why is hydrogen chloride a gas at room temperature(3)?

Answer 19

• hydrogen chloride is a small molecule
• it has weak intermolecular forces
• which require a weak amount of energy to overcome

Question 20

Why is chlorine more reactive than iodine?(3)

Answer 20

• reactivity decreases down the group
• the space between chlorine the nucleus and the electrons is bigger
• making it easier for chlorine to gain electrons

Question 21

Polymer [definition]:

Answer 21

A large molecule that is made of many repeating subunits