Flashcards for OCR 21st Century Science C4

Quick revision for C4 Chemical Patterns

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  • Created by: isis
  • Created on: 18-01-13 19:57
What does the oxidising symbol mean?
Provides oxygen which allows other materials to burn more fiercely e.g. Liquid Oxygen
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What does the highly flammable symbol mean?
Catches fire easily e.g. petrol
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What does the toxic symbol mean?
Can cause death either by swollowing, breathing in or absorption through the skin e.g. Hydrogen Cyanide
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What does the harmful symbol mean?
It is like toxic bu not as dangerous e.g. copper sulfate
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What does the explosivve symbol mean?
Can explode e.g. some peroxides
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What does the corrosive symbol mean?
Attacks and destroys living tissues including skin and eyes e.g. concentrated sulfuric acid
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Describe the safety precautions when using the alkali metals.
1 stored in oil so they do not come in contact with water vapour 2 do not touch with bare hands as the sweat on your skin can be enough to cause a reaction producing heat and a corrosive hydroxide
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Describe the safety precautions when using the halogenas
1 as halogens have poionous vapours that iritate the respiratory system and the eyes they must be used within a fume cupboard 2 liquid bromine is corrosive so contact with skin must be avoided 3 chlorine and iodine are very toxic
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What is another name for group one metals?
The Alkali metals as when they react with water they make an alkaline solution
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As you go down group 1 what happens to the properties of the metals?
become more reactive, have a high density, lower melting point and lower boiling point
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What happens to lithium, sodium or potassium if they are put in water?
they react vigorously, moving around the surface and fizzing furiously. they produce hydrogen. potassium gets hot enough ti ignite it.
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What does placing alkali metals in water show?
it shows the rtealtive reactivities of the alklai meatls.
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What is another name for group seven element?
The halogens
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Describe the structure of the halogens?
they all have seven electrons in the outer shells, anform diatomic moleculs through covalent bonding.
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As you go down group 7 what happens to the properties of the elements?
become less reactive, have a higher melting point have a higher boiling point.
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Describe what thestate of the halogens at room temperature and pressure.
Flourine is a very reactive poisonous yellow gas, chlorine is a fairly reactive poisonous dense green gas, bromine is a dense poisonous orange volatile liquid and iodine is a dark grey crystalline solid or a purple vapour.
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How can the trend in reactivity of the halogens be shown?
Through reactions with alkali metals as the reactions become less vigorous as you go down the group, reactions with iron as the reactions become less vigorous as you go down the group, and displacement reactions
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What are ions?
they are charged particles that have lost or gained electrons.
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Why do atoms gain or lose electrons?
They are trying to get a full outer shell as this is where they are most stablel.
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What did Dobereiner do to organise elements?
in 1828 put the list of elements into groups based on their chemical properties. These groups were called triads. the middle element of each triad had a relative atomic mass that was the average of the other two.
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What was Newland's law of octaves?
He arranged the elements in order if relative atomic mass, every eighth element had similar properties so he listed some of known elements in rowns of seven.
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Why was Newlands' work critised by the Chemical Society in 1865?
1 his groups contained elements that didn't have similar properties e.g. carbon and lithium, 2 he mixed up metals and non-metals e.g. oxygen and iron, 3 he didn't leave any gaps for elements that hadn't been discovered yet/
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What did Mendeleev do in 1869?
He put the elemnts in order if atomic mass. BUT he found that he had to leave gaps in order to keep elements with similar properties in the same vertical groups.
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Why were the gaps left by Mendeleev clever?
They predicted the properties of so far undiscovered elemtens. When they were found and they fitted the pattern it helped to confirm Medeleev's idea.
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Why do ifferent elements produce different coloured flames/
Diferent elements emit different wavelengths of light due to each element having a different electron arrangement.
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What is the pratical technique used to produce line spectrums called?
Spetroscopy
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What has new technology allowed scientists to do?
Techniques such as spectroscopy have allowed scientists to discover new elements.
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Give example of elements that have been discovered by line spectrum?
Caesium and rubidium were discovered by their line spectrum and helium was discoveredn in the line spectrum of the Sun.
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Other cards in this set

Card 2

Front

What does the highly flammable symbol mean?

Back

Catches fire easily e.g. petrol

Card 3

Front

What does the toxic symbol mean?

Back

Preview of the front of card 3

Card 4

Front

What does the harmful symbol mean?

Back

Preview of the front of card 4

Card 5

Front

What does the explosivve symbol mean?

Back

Preview of the front of card 5
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