Topic 2 - Bonding. Structure, And Properties Of Matter Flashcards
What’s an ion
A charged particle
What are positive ions called
Cations
What are negative ions called
Anions
What’s ionic bonding
- a metal and a non metal reacting together, the metal forms a positive ion and the non metal forms a negative ion
- the oppositely charged ions are strongly attracted to one another by electrostatic forces
What’s the limitations of dot and cross diagrams
They don’t show the structure of the compound, the size of the ions, or how they are arranged
What structure do ionic compounds have
Giant ionic lattice - closely packed regular lattice arrangement with strong electrostatic forces of attraction between the oppositely charged ions
What are the properties of ionic compounds
- high melting and boiling points due to the many strong bonds between the ions
- conduct electricity when dissolved or molten
What’s covalent bonding
Non metals sharing electrons - the positive nuclei are attracted to the negative electrons by electrostatic forces
What are simple molecular substances made up of
Molecules containing a few atoms joined together by covenant bonds e.g water
What are the properties of simple molecular substances
- low melting and boiling points as the forces of attraction between the molecules are weak
- most gases or liquid at room temperature
- don’t conduct electricity
What’s a polymer
Lots of small units joined together to form a long molecule - joined by strong covalent bonds
What’s a giant covelant structure
All the atoms are bonded to each other by strong covalent bonds e.g diamond
What are the properties of giant covalent structures
- High melting and boiling points
- don’t conduct electricity (mostly) as it don’t contain charged particles
Describe the structure of diamond
Each carbon atom forms 4 covalent bonds in a very rigid giant covalent structure
What are the properties of diamnond
- very hard
- very high melting point
- doesn’t conduct electricity
What’s the structure of graphite
Each carbon atom only forms 3 covalent bonds creating sheets of carbon atoms arranged in hexagons - no covalent bonds between the layers so they are free to move over each other
What are the properties of graphite
- soft and slippery (ideal lubricating material)
- high melting point
- can conduct electricity - each carbon atom has one electron that’s delocalised
What’s graphene
One layer of graphite
What are the properties of graphene
- very strong and also very light (added to composite materials to improve their strength without adding much weight)
What are fullerenes
Molecules of carbon shaped like closed tubes or hollow balls - mainly made up of carbon atoms arranged in hexagons but can also contain pentagons or heptagons
What are fullerenes used for
- they could be used to deliver drugs to the body as they can ‘cage’ other molecules
- Good industrial catalysts - high surface area
- can form nanotubes - tiny carbon cylinders
What are the allotropes of carbon
- diamond
- graphite
- graphene
- fullerenes
What are the properties of nanotubes
- can conduct electricity and heat
- high tensile strength (stretchable)
- strengthen materials without adding weight
What’s metallic bonding
- electrons in the outer shell of the electron are delocalised
- this creates strong forces of electrostatic attraction between the positive metal ions and the shared negative electrons
What’s an alloy
A mixture of two or more metals or a metal and another element- distorting the layers making them harder than pure metals as the layers can’t slide over each over
How big are nanoparticles
They have a diameter between 1nm and 100nm
What are nanoparticles used for
1) catalysts- large surface area to volume ratio
2) nanomedicine - delivering drugs ets - tiny particles absorbed more easily
3) tiny electrical circuts for computer chips
4) sliver nanoparticles - antibacterial propertie- surgical masks, wound dressings, deodorant etc
5) cosmetics - improving moisturisers etc
6) suncream- better coverage
What are the downsides of the use on nanoparticles
- the way the affect the body isn’t fully understood- may be damaging
- May damage the environment
