C3 Flashcards
What is graphene?
A single layer of graphite and has properties that make it useful in electronics and conmposites a
What are the properties of graphene?
- excellent conductor of electricity and thermal energy
- very low density
- most reactive form of carbon
- pieces of it are incredible strong for its mass
What are fullerenes?
Molecules made of carbon atoms with hllow shapes . The structure of fullerenes is based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms.
What was the first fullerene to be discovered?
Buckminsisterfullerene c60 which had a speherical shape
What are carbon nanotubes?
Cylindrical fullerenes with very high length to dimater ratios. Their properties make them useful for nanotechnology, electronics and materials.
What are the molecular forces like between buckministerfullerene?
Weak intermolecular forces between molecules
-slippery and low melting point
What are the states of matter?
- solids
- liquid
- gases
What is the difference between the volume and shape of the three states of matter?
- solids have fixed shape and volume
- liquids have a fixed volume but can change their shape
- gases have no fixed shape or volume , they can be compressed easily
What does particle theory describe?
- movment of particles
- average distance between particles
How close are the state of matters particles together?
- solids particles touch
- liquids particles touch but move around aswell
- gas particles do not touch
What is needed for a solid to become a base?
Heat which will break bonds between atoms and increase the energy making particles move around faster and increase collisions between particles making them move around rapidly
What takes place at the maelting point?
Melting and freezing
What takes place at the boiling point?
Boiling and condensing
What is the reason for a substance having a high boiling or melting point?
Strong forces between particles.
What are the three types of bonding?
Ionic , covalent and metallic
What compounds does ionic bonding occur in?
Metal and non metal
What compound does covalent bonding occur in?
Non metal and non metal
What does metallic bonding occur in?
Metallic elements and alloys
How do atoms gain a stable valence shell?
- ionic bonding
- covalent bonding
What happens during ionic bonding?
Metal atom loses electron to become positively charge ion or a non metal gains an electron to become a negatively charged ipn
What is an ionic compound?
A giant structure of ions
What holds ionic compounds toegther?
Strong electrostatic forces between oppositkey charged ions. These forces act in all directions in a lattice structure, this is ionic bonding.
What is covalent bonding?
When atoms shair pairs of electrons , froming bonds that are strong
What may covalently bonded substances consist off?
Small molcules
What covalently bonded substances have very large molecules?
Polymers
What are examples of giant covalent structures?
Diamond
Silicon dixoide
What is metallic bonding?
Two metals reacting , forming bonds
What do metals atoms consist off?
A giant structure of atoms in a regular repeating pattern
What is the electrons configuration for metallic bonding?
Electrons in the outer shell are delocalised and so are free to move through the structure.
What are the properties of ionic compounds?
- high melting points
- high boiling points, because large amount of energy needed to break bonds
How do you make ionic compounds conduct electricity ?
Melt it or dissolve it in water. This frees up the so ions charge can flow .
What state are small Covalent molecules usually found in?
Gases or liquids
What are the melting points of small covalent molecules?
Low melting and boiling points
How strong are small Covalent molecules intermolecular forces?
- weak intermolecular forces
- overcome when melted or boiled
What happens as molecules get bigger?
Intermolecular forces increase so larger molecules have high melting and boiling points
Do small Covalent molecules conduct electricity ?
No because they have no overall electric charge
Properties of polymers?
- very large molecules
- atoms in polymer molecules are linked to other atoms by strong covalent bonds
- intermolecular forces are strong
- solids at room temperature
What are giant covalent structures?
Substances that are solids with very high melting points, covalently bonded.
What is bonding like in giant covalent structures?
All atoms linked by strong covalent bonds
How to melt or boil a giant covalent strcutre?
Overcome the strong covlent bonds .
Properties of metals and alloys?
Metals have a giant structure of atoms with strong metallic bonding. Means most metals have high melting and boiling points
What is the structure and properties of a pure metal?
- atoms are arranged in layers
- can be bent and shaped
- soft
What are alloys?
Metals mixed together . They are harder than just a pure metal
Are metals good conductors of electricity?
Yes, because delocalised electrons carry electrical charge through the metal. Metals are good conductors of thermal energy because energy is transferred by the delocalised electrons.
What are the properties of diamond?
- formed from carbon
- each carbon atoms forms four covalent bonds with other carbon atoms in a giant covalent structure
- diamond is very hard
- has a very high melting point
- does not conduct electricity
Properties of graphite?
- made of carbon
- each carbon atom forms three covalent bonds with three other atoms, forming layers of hexagonal rings which have no covalent bonds between layers
Are graphite electrons delocalised?
Graphite has 1 delocalised electrons
Why can metals be bent and shaped?
Metal ions can slide over each other
How are metals structured?
-strong electrostatic attraction between sea of delocalised negative electrons and positive metal ions
Why can delocalised electrons carry a current?
Because they are charged
Why are alloys harder?
Mixture of metals. The different sizes of atoms distorts the layers , making it more difficult for them to slide over each other
