C2 Flashcards
What is an ion?
Charged particles can be made of single atom (Cl-) or group (NO3-)
metal= lose= +, non-metal= gain -
Why do atoms try to gain a full outer shell?
- Lose or gain electrons to gain full outer shell
- Full outer shell called stable atomic structure it is a very stable element
Groupo 0= full outer shell
Draw the half eqation for Na when forming an ion
group 1
Na-> Na(=) + e(-)
loses 1 electron
Draw the half eqation for O when forming an ion
Group 6
O+ 2e(-)->O^(2-)
What is ionic bonding?
- Metal+ Non-metal react together
- Metal becomes positive +
- Non-metal becomes negative -
- There are strong electrostatic forces for attraction between the oppositly charged ions= ionic bond
Draw a dot and cross digram for Magnesium chloride (MgCl2)
What is the structure and forces of ionic compounds?
- Giant ionic lattice
- Ions are closely packed in regular lattice arragment
- Very strong electrostatic forces of attraction between the ions in all directions
What are the properties of ionic compounds? Justify why.
- High **melting **and boiling points-> strong bonds between ions require lots of energy to overcome
- Cann’t conduct when solid-> ions are held in place
- Can conduct when molten-> ions free to move= carry electric current
- ** Can conduct** when dissolved in water-> ions are seperate and free to move in soltion=carry current
What is the empirical formular of the ionic compound below?
What is covalent bonding?
- Non-metal + Non-metal bond bond together sharing electrons (outer shell) to make colavlent bonds
- positivly charged nucli of bonded atoms are attracted to shared pair of electrons by electrostatic forces= strong covalent bonds
*
Draw the dot and cross digram to show the bonding in NH3
What does the dot and cross digram show?
What are the limitations of the dot and cross digram?
+dot and cross show ere each electron comes form
+ good for showing large molecules
- - Dosn’t show relative sizes of the atoms or how they are arraged in a space
- Dosn’t show the 3D structure of the molecule or
£d ball and stick digrmas can get very confusing
What is the bonding and structure of simple molecular subsances?
Molecules containg a few atoms joined together by covalent bonds
What is the bonding and structure of Hydrogen?
- 1 electron, one more needed to complete the first shell
- Bonds to form single covalent bonds e.g with hydrogen
- Simple molecular
What is the bonding and structure in Nitrogen?
- Needs 3 more electrons
- 2 nitrogent atoms shre 3 pairs of electrons
- Triple bond
- Simple molecular
What are the properties of simple molecular substance? Why is this?
Bonding:
* Substances containing covalent bonds usally= simple molecular structure
* Atoms within moleculs held together with very strong covalent bonds
* However…….. forces of attraction between molecules ( intermolecular) forces are very weak
Properties:
* Melting point is very low-> Only need to break feeble intermolecular forces not covalent= moleculs are easly parted
* Most molecualr substances are gass at room temp ( oxygen).
* Don’t conduct electrity-> arnt charged ions= no free elctrons/ions
What happens to the properties of a simple molecular subtance as it gets bigger?
- Bigger= strength of the intermolecular forces increase=> more energy needed to break them=> increased melting and boiling points
What is a polymer? What kind of bonding has it got?
- Giant covalent substance
- Lots of small units linked together to form a long molecule with reapeating sections
- All atoms in polymer joinged by strong covalent bonds
Whta re the properties of polymers and explain them.
- Solid at room temp->Intermolecular forces bewtween molecules are larger then simple covalent=> more energy needed to break them.
- Low melting and boiling points-> intermolecular forces are weaker thne ionic + covalent= lower boiling points than ionic/ giant compounds
What are the general properties and structure of Giant covalent structures?
- All atoms are bonded to each other by strong covalent bonds
- Very high melting and boiling points= lots of energy needed to break the covalent bonds between atoms
- Don’t conduct electrity->( even when molten) Don’t contain charged particels (some exceptions).
Describe the bonding and structur in Silicon dioxide
- Sometimes called silica
- Giant covalent structure
Describe the structure and properties of diamond.
Uses
- Giant covalent structure
- Made of carbon atoms, each carbon forms 4 covalent bonds-> realy hard
- Very high melting point->Strong covalent bonds take a lot of energy to break
- Donsn’t conduct-> no free electron
Jewlery, drill bits
Describe the structure and properties of Graphite.
Uses
- Each carbon atom forms 3 covalent bonds=> sheets of carbon atoms arranged in hexagons
- Soft and slippery (Lubricationg material)->No covalent bonds between layers, held together weakly=> free to move over each other
- High melting point-> covalent bonds between layer= lots of energy to break
- Conducts electrity and thermal energy-> 3 of 4 of carbons outer electrons used in bonds= delocalised elecctron with is frre to move and carry a charge through the structure
Lubrication materials
Describe the structure and properties of Graphene
- Sheet of carbon atoms joined together in hexagons, 1 atoms thick ( 2D)
- Network of covalent bonds->strong
- 1 atom thin-> light & added to composite materilas to improve strenght without adding to weight
- can conduct elecricity-> delocalised electron can carry a charge through the structure=> electronics
electronics, added to compostive materials
What are fullerens?
- Fullerene-> Molecule of carbon shaped in closed tubes or hollow balls
- Can be in hexagons, pentagons………
- Deliver drugs ( around body)-> Can ‘cage’ other molecule
- Catalyst-> Huge SA= moleculas can be attached to fullerne
Lubricans, drug delivery, catalyst
What is Buckminsterfullerene?
First fulleren discovered, hollow sphere
What are nanotubes
- Fullerene
- Tiny carbon cylinder
- High length to diameter ratio
- Conduct themal + electrical energy
- High tensile strength( don’t break when streched)
- Nano tech: electronics, strenghten materials withought adding to weight (tennis racket frames)
Describe the structure and properties of metalic bonding.
- Giant structure
- Electrons in outer shell= delocalised
- Strong forces of electrostatic attraction between positive metal ion and shared negative electrons
- Metalic bonding ->Forces of attraction hold atoms together in regular structure, very strong bonding
- Metalic bonding is in alloys and metals
What is the trend in boiling points in metallic bonding?
- Electrostatic forces between metal atoms and delocalised sea of elctrons are strong and need lots of energy to be brocken
Hence:
->Very high melting point
-> solid at room temp
Do matalic substances conduct electrcity?
Can conduct heat and electricity
Delocalised electron is free to carry a charge through the structure
Are metalic substances malleable?
Layers of of atoms can slide over each other= malleable
Can be bent hammered or rolled into falt sheets
Why are Alloys harder then pure metals?
- Pure metal= too soft
- Alloys=harder than pure metals
- Diffrent elements have diffrent sized atoms so when anouther element is mixed with pure metal=it distorts the layers => more difficult to slide over each other=> harder than pure metals
Define Alloy
Alloy-> mixture of two or more metals of anouther element
What determins the state of a material?
- Depends on how strong the forces of attraction between thae particles of the material
Strength of forces baised on:
1) Material (structure and bonding bewtween particles)
2) Temp
3) Pressure
In a solid decribe the forces flow ect.
- Strong forces of attraction between particles holding them close together in fixed positions in very regular lattice arrangement
- Don’t move from their postion all solids keep definte shape and volume
- Don’t flow
- Vibrate about there postions: the hotter solid becomes= more they vibrate ( expand when heated
In a liquids decribe the forces flow ect.
- Weak force of attraction between particles
- Randomly arranged and free to move past each other but stick closly together.
- Liquids have definite vol don’t keep definite shape ( fill bottem of a container)
- Particles move constantly with random motion. Hotter liquid gets the faster they move ( expand when heated).
In a gases decribe the forces flow ect.
- In gasas force of attraction between particles are weak, thy’re free to move far apart
- Particles move in staight lines
- Gasas don’t keep definte shape/vol and will fill container
- The particles move constantly with random motion. hotter gas gets= faster they move (eather expand when heated or preasure increases).
What are the issues with the particle theory of states of matter?
- Particles arn’t solid or inelastic and not spheres they’re atoms ions or moleculs.
- Don’t show the forces between particles= can’t see the strength of them
What does Aqueous mean?
Dissolved in water (aq)
What is a physical change?
No change of particles just their arrangement or energy
Describe what happens when a solid is heated to liquid?
- Solid is heated it’s particles gain more energy.
- Makes particles vibrate more which weakens the forces that hlod solid together.
- At certain temp (meltiong point) particles have enough energy to break free form their postions= melting S->L
What happens when a liquid i heated to a gas?
- Liquid is heated the particles get even more energy
- This energy makes the particles move faster which weakens and breaks the bonds holding the liquid together
- At certain temp (boiling point) particles have enough energy to break their bonds=boiling ( evapourationg)
L->G
What happens as a gas cools into a liquid?
- As gas cools particles no longer have enough energy to overcome forces of attraction between them.
- Bonds form between particles
- At boiling point so many bonds have formed between gas particles that the gas becoms liquid=Condensation
What happens when a liquid cools into a solid?
- Liquid cools particles have less energy
- There’s not enough energy to overcome attraction between particles so more bonds form between them
- At the melting point so many bonds have formed that they’re held in places. L->S= freezing
What is the convertion: 1nm->xm
1nm= 0.000,000,001
What is a coarse particle?
PM10
diameter 2,500nm-10,000nm
Also called dust
What is a fine particles
PM2.5
diameter 100nm-2500nm
What is a nanoparticle?
diameter 1nm-100nm
They only contain a few hundred atoms
nanoscience-> science that looks at uses+ properties of nanoparticles
What are the properties of nanoparticles?
- Nanoparticles have high SA:Vol-> As particles decrease in size their SA:Vol increases ( very high SA compaired to it’s vol)
- This chages propeties of material depending if it’s a nanoparicle or in bulk e.g. leff on catalyst made of nanopartices compaired to noramal sized particles (with billions of atoms)
What are the uses of Nanoparticles?
- Catalysts-> high SA:Vol
- Nanomedicine-> tiny particles (e.g fullerenes) are absorbed into body more quickly= could deliver drugs to specific cell in wich they are needed.
- Electric circuits->Conduct electricty= computer chip
- Surgical masks, wound dressings, deodorants-> Silver nanoparticles have antibacterial properties. Can be added to polymer fibers.
- Cosmetics->e.g added to improve moisturisers without making them oily
sunscreen
Why may some be against Nanoparticles?
- They way they affect the body isn’t fully understood=> should be testing on new products to decrease risk
- Some say it has been used without knowlage of it’s impact long term
- Nanoparticles are clearly labled= consumer chose
How and why are nanoparticles used in sunscreen? What are the downsides?
- Nanoperticles are better thhan traditional at protecting form UV
- Better skin coverage
- Not clear if nanopartices can enter body and if that may damage cells
- When washed away may damage the enviroment
