Chemistry Topic 2- Bonding, Structure and Properties of Matter

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What is an ion?
A charged particle- it can be a single atom or a group of atoms.
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What happens when metals form ions?
They lose electrons to form positive ions (cations).
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What happens when non-metals form ions?
They gain electrons in their outer shell to form negative ions (anions).
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When does ionic bonding occur?
When a metal and non-metal react. The oppositely charged ions are strongly attracted to one another by electrostatic forces.
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What kind of diagrams show ionic compounds?
Dot and cross diagrams.
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What is the structure of ionic compounds?
They form a giant ionic lattice, where the ions form a closely packed regular lattice with strong electrostatic forces of attraction between ions in all directions.
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What are the properties of ionic compounds?
High melting and boiling points due to the strong electrostatic bonds. Can conduct electricity when dissolved or molten as the ions are free to move and carry electric current.
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When do covalent bonds occur?
When two non-metal atoms bond together, as they share pairs of electrons to make covalent bonds.
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Why are covalent bonds strong?
The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces.
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What are simple molecular structures?
They are made up of molecules containing a few atoms joined together by covalent bonds
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Give 7 examples of simple molecular structures.
Hydrogen, oxygen, methane, chlorine, nitrogen, water, hydrogen chloride.
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What are the properties of simple molecular structures?
Low melting and boiling points due to the week intermolecular forces of attraction, do not conduct electricity as they are not charged.
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What is a polymer?
Lots of small units linked together to form a long molecule that has repeating sections. All the atoms are joined by covalent bonds.
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What are the properties of a polymer?
They have larger intermolecular forces so more energy is needed to break them, and most polymers are solid at room temperature.
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What is a giant covalent structure?
All the atoms are bonded to each other by strong covalent bonds.
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What are the properties of a giant covalent structure?
They have very high melting and boiling points, but do not conduct electricity (except graphite).
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What is an allotrope?
A different structural form of the same element.
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Diamond
Each carbon forms four covalent bonds. It is very hard due to this rigid structure.
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Graphite
Each carbon atom forms three covalent bonds, creating sheets of carbon atoms arranged in hexagons. The layers are held together weakly, so graphite is soft and slippery. It has one delocalised for each carbon so it can conduct electricity.
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What is graphene?
One layer of graphite. It is very strong but also incredibly light, and can conduct electricity.
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What are fullerenes?
They are molecules of carbon shaped like closed tubes or hollow balls, they're mainly made up of carbon atoms arranged in hexagons but can also contain pentagons or heptagons.
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What can fullerenes be used for?
They can be used to cage other molecules, trapping another atom/molecule inside. This could deliver a drug into the body.They also make good lubricants.
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Why is a big surface area useful?
It means that fullerenes make good industrial catalysts, as individual catalysts can be attached to fullerenes.
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What are nanotubes?
Tiny carbon cylinders formed by fullerenes. The ratio between their length and diameter is very high.
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What are the properties of nanotubes?
They can conduct electricity and heat, they have a high tensile strength (do not break when stretched).
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When does metallic bonding occur?
This occurs only between metals. It is where the electrons in the outer shell of the atoms are delocalised. They are strong forces of electrostatic attraction between the positive metal electrons and negative electrons.
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Why is metallic bonding strong?
The forces of attraction hold the atoms together in a regular structure.
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What are the properties of metals?
They have high melting and boiling points due to the strong electrostatic forces. They are good conductors due to the delocalised electrons. They are malleable because the layers can slide over each other- they can be bent, hammered or rolled.
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Why are alloys harder than pure metals?
This is because when another element is mixed with a pure metal, the new atoms will distort the layers, so they can't slide over each other as easily.
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What three things does the strength of forces between particles depend on?
The material, the temperature and the pressure.
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Describe a solid.
There are strong forces of attraction between particles, holding them close together in fixed positions. The particles don't move so solids keep a definite shape and volume. The particles vibrate, so they expand slightly when heated.
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Describe a liquid.
There are weak forces of attraction between particles, making them randomly arranged and free to move past each other but usually stick close together. They have a definite volume but not a definite shape as they flow.
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Describe a liquid (cont.)
The particles are constantly moving in random directions, and move faster when hotter meaning they expand slightly when heated.
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Describe a gas.
The forces of attraction are very weak, so the particles are free to move and are far apart. They travel in straight lines but don't keep a definite shape or volume and will fill any container. The particles move constantly and randomly.
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What are the diameters of coarse particles, fine particles, and nanoparticles?
Coarse= between 2500 and 10000nm. Fine= between 100 and 2500nm. Nanoparticles= between 1 and 100nm. They are particles that only contain a few hundred atoms.
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How do you calculate surface area to volume ratio?
surface area to volume ratio= surface area / volume
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What's special about the surface area to volume ratio in nanoparticles?
It is very high, causing the properties toe be different. You'll often need less of a material made up of nanoparticles to work as an effective catalyst.
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What are the uses of nanoparticles?
new catalysts, nandomedicine (absorbed more easily into body), tiny electric circuits for computer chips, antibacterial properties can be added to polymer fibres, cosmetics.
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What is the problem with using nanoparticles?
The way they affect the body isn't fully understood, so new products should be thoroughly tested. They are being used in sun creams as they give better skin coverage and protect skin better, but they may get into your body or damage the environment.
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Other cards in this set

Card 2

Front

What happens when metals form ions?

Back

They lose electrons to form positive ions (cations).

Card 3

Front

What happens when non-metals form ions?

Back

Preview of the front of card 3

Card 4

Front

When does ionic bonding occur?

Back

Preview of the front of card 4

Card 5

Front

What kind of diagrams show ionic compounds?

Back

Preview of the front of card 5
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