C2: Structure, Bonding and Properties of materials Flashcards
1
Q
Ionic bonding(8):
A
- 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)
2
Q
Covalent bonds(4):
A
- 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
3
Q
Metallic bonding(4):
A
- 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
4
Q
What is an alloy?
A
A mixture of two or more elements at least one of which is a metal
5
Q
Properties of alloys(2):
A
- 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
6
Q
Metals as conductors(2):
A
- 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
7
Q
State changes(3):
A
- 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
8
Q
Ionic bonding in metals(2):
A
- Metal atoms loose electrons and become positively charged ions;
- group 1 metals form + 1 ions
- group 2 metals form +2 ions
9
Q
Ionic bonding in non metals(3):
A
- non metal atoms gain electrons to become negatively charged ions
- group 6 non metals form -2 ions
- group 7 non metals form - 1 ions
10
Q
Graphene(5):
A
- excellent conductor
- very strong
- a single layer of graphite is one atom thick
- contains delocalized electrons
- contains strong covalent bonds
11
Q
Allotropes of carbon/ giant covalent structures(5):
A
- diamond, graphite and silicon dioxide
- very high melting points
- lots of energy needed to break their strong, covalent bonds
12
Q
Properties of small molecules(6):
A
- 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)
13
Q
Properties of a polymer(4):
A
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
14
Q
Diamond(7):
A
- 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
15
Q
Graphite/ layers of graphene(7):
A
- 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
16
Q
Fullerenes:
A
- hexagonal rings of carbon atoms with hollow shapes
17
Q
Carbon nanotubes(7):
A
- 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
18
Q
Nanoparticles(8):
A
- 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
19
Q
Why is hydrogen chloride a gas at room temperature(3)?
A
- hydrogen chloride is a small molecule
- it has weak intermolecular forces
- which require a weak amount of energy to overcome
20
Q
Why is chlorine more reactive than iodine?(3)
A
- reactivity decreases down the group
- the space between chlorine the nucleus and the electrons is bigger
- making it easier for chlorine to gain electrons
21
Q
Polymer [definition]:
A
A large molecule that is made of many repeating subunits
