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- Created on: 15-06-20 16:52
What is ionic bonding?
- An electrostatic attraction between ions of opposite charge
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Features of a homologous series
- M1) Similar chemical properties
- M2) Trend in physical properties
- M3) Same functional group
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Why any ionic compound has a high m.p./b.p.
- M1) Attraction between ions is very strong
- M2) Lots of ions in a giant lattice structure
- M3) Therefore a lot of energy needed to break bonds
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Why an ionic solid does not conduct electricity bu
- In solids no ions are free to move while in liquids ( molten/ aqueous) they can move / be mobile
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Metal bonding and structure
- Positive ions are surrounded by a sea of delocalised electrons creating a strong electrostatic attraction between them
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Why does a metal conduct electricity?
- It has a sea of delocalised electrons that are free to move
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Why are metals malleable?
- Metal ions are arranged in layers that can slide over each other
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Why does a compound have a low b.p./m.p.?
- It has weak intermolecular forces therefore little energy required to overcome
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Importance of cracking
- M1) Greater supply of long chain hydrocarbons
- M2) Higher demand for short chain hydrocarbons
- M3) The alkenes produced can be used to make polymers/ plastic etc. Short chain - saturated - are used as fuels
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Bromine water with alkene and alkane
- Alkene = Orange to colourless
- Alkane = No change unless UV light is present, even then reaction is slow
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Observations of metals in acid ( specifically K an
- M1) Solid dissolves/ dissapears
- M2) Bubbles/ fizzing as gas forms
Specific to K and Na
- M3) Sodium darts around and melts into a ball
- M4) Potassium burns with a lilac flame
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Why do covalent compounds not conduct?
- They have NO charged particles
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Why does increase in temprature result in a faster
- Particles have more energy so there are more collisions per second, they have an energy greater than activation energy therefore more collisions per second
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What is a redox reaction?
- M1) Both reduction and oxidation take place at the same time
- M2) [Mention specific to the question what is reduced and oxidised]
- M3) [Say why it is, e.g. A loses oxygen which is gained by B]
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Why would you repeat an experiment?
- M1) To obtain concordant results
- M2) To identify anomalous results
- M3) To obtain a mean of concordant results
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What is a catalyst
- M1) A substance that increases the rate of reaction
- M2) And remains chemically unchanged/ not used up
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What does a catalyst do?
- M1) Provides an alternative reaction pathway
- M2) Which lowers the activation energy
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Lower temp or energy change than expected?
- Often the reason is heat/ energy is lost to surroundings
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