Chemistry C2.2

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Ionic compounds have a regular arrangement of ions called what?
A giant ionic lattice
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Ionic compounds have high boiling points and high melting points, why?
Because there is a strong electrostatic attraction between the negative and positve ions, resulting ina bond that is difficult to overcome.
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When melted, why do ionic compounds carry electric current?
Because the ions are free to move
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Do Ionic compounds carry when electric current when dissolve? Explain. Are they dissolved easily in water?
Yes because the electrons are free to move in the solution and therefore they'll carry electric current. They do dissolve easily in water
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What are simple molecules?
substances with covalent bonds that are made up of a few atoms
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What are the three main properties of simple molecules(SMs)?
They have low melting and boiling points, they are mostly gases or liquids at room temperature because of low melting and boiling points and they don't conduct electricity because there are no ions or free electrons so there is nothing to carry the c
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In SMs what bonds: a) the atoms in the small molecules b) the small molecules themselves?
a) Covalent bonds b) Weak intermolecular forces
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Which one of these gets broken when SMs melt or boil, how does it affect the melting and boiling points, why?
The weak intermolecular forces are broken. This measn that he boiling and melting points are lower because less energy is required to overcome these bonds.
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What makes a macromolecule different to a lattice?
It has no charged ions and all the atoms are bonded covalently, making them stronger.
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What is the hardest natural substance, is it a macromolecule or a lattice?
Diamond, it is a macromolecule.
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carbon has 4 atoms on its outer shell, how many are usually covalently bonded in macromolecules? How many are in graphite? What do the leftovers become?
4, 3, delocalised electrons.
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What do these extra electorns do? What does this mean graphite can do? Why is this peculiar?
They move freely throughout the structure, this means graphit can conduct heat energy and carry a current, most macromolecules cannot do this.
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Apart from delocalised electrons, wast does, Graphite only having 3 covalent bonds per atom mean? Why does it mean that Graphite is soft and slippery?
It means that Graphite forms layers connected by weak intermolecular forces, these are easily overcome so they easly silde over each other.
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What does malleable mean? Why are pure metals malleable?
able to bent or shaped. Because the atoms are in a regular structure which means that the atoms are able to slide over each other.
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Why are metals good conductors of heat and electricity?
Because they have delocalised electrons which carry current and heat energy through the structure.
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What is an alloy? Why are they created?
two or more metals mixed together. Pure metals aren't quite right for certain jobs
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Why are alloys stronger than pure metals?
Because the atom of the new metal is a different size and will therefore distort the layers of the first metal, making it harder for them to slide over one another.
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What are smart materials? Name a type of smart material, what do they do?
Materials that behave differently depending on the conditions. Shape memory alloys, they will return to an original shape after being moved.
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Name a shape memory alloy and its use.
Nitinol, its useful for glasses frames.
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What are nanoparticles?
Tiny particles, 1-100 nanometres across, containing roughly a few hundred atoms. Very different properties to the bulk chemical it comes from.
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Name two uses of nanoparticles
they have a huge surface area to volume ratio, so they make good catalysts. Nanotubes are conductive and can be used in circuits for tiny computer chips.
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What are fullerenes?
a type of nanoparticle, molecules of carbon, shaped like hollow balls or closed tubes. They are arranged in hexagonal rings.
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What are the 3 uses of fullerenes?
Fullerenes can be used in lubricants as catalysts. They could one day be used in medicine because they are absorbed more easily by the body. they can be joined together to make nanotubes which are strong and conductive.
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What are thermosoftening polymers made out of? Thermosetting polymers?
individual tangled chains of polymers. They have cross-links between their polymers which means they do not melt, instead they burn.
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What are the properties of thermosetting polymers?
The cross-links mean that they are very strong, hard and rigid because cross-links hold their chains firmly together.
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What are the properties of thermosoftening polymers?
Chains are held together by weak intermolecular forces and are free to slide over each other. The force between chains are easy to overcome, so they easily melt. They harden when cooled. You can melt and remould infinitely, so they recycle easily.
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What can affect the properties of polymers when they are formed? Give an example.
The starting materials and reaction conditions. Low density ethen is mad by heating ethene to about 200 degrees under high pressure. High density polyethene is made with a lower temperature and pressure.
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Other cards in this set

Card 2

Front

Ionic compounds have high boiling points and high melting points, why?

Back

Because there is a strong electrostatic attraction between the negative and positve ions, resulting ina bond that is difficult to overcome.

Card 3

Front

When melted, why do ionic compounds carry electric current?

Back

Preview of the front of card 3

Card 4

Front

Do Ionic compounds carry when electric current when dissolve? Explain. Are they dissolved easily in water?

Back

Preview of the front of card 4

Card 5

Front

What are simple molecules?

Back

Preview of the front of card 5
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