C5

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  • Created by: Faith16
  • Created on: 13-12-15 14:25
What are the different percentages of gases in the Earths atmopshere?
78% nitrogen, 21% oxygen, 1% argon and 0.4% carbon dioxide
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Give an example of a molecular substance in the Earths atmosphere.
Carbon dioxide or water
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What are the properties of molecular substances?
They are held together with very strong covalent bonds but have weak forces of attraction. They have very low melting and boiling points (either water or gas at room temperature) and they don't conduct electricity.
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What is covalent bonding?
When two atoms share electrons in order to get a full outer shell. This is due to the electrostatic attraction between the positive nuclei and the negative electrons shared between the atoms.
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Give an example of a single covalent bond and a double covalent bond.
Singe- hydrogen (only needs one extra electron to fill outer shell) Double- Carbon dioxide (carbon needs 4 electrons and oxygen needs 2)
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What is the earths hydrosphere?
It consists of all the water in the oceans,seas, lakes, rivers and puddles (all the water on earth)
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Why is the sea salty?
As the hydrosphere also contains all the compounds that are dissolved in the water, most of these are salt such as sodium chloride, magnesium chloride and potassium bromide.
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What are ionic compounds?
They are made up of charged particles called ions. Ions with the opposite charges are strongly attracted so you get a massive giant lattice. They have very strong ionic bonds. A single crystal of salt is one giant ionic lattice.
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What are the properties of ionic compounds?
Strong ionic bonds and forces. Very high melting and boiling points so they are solids at room temperature. Only conduct electricity when dissolved or molten.
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What are the flame test colours for sodium, potassium, calcium and copper?
Sodium- orange/yellow Potassium- lilac Calcium- brick red Copper-bluely green
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What are the precipitates of the following elements when adding sodium hydroxide (NaOH)? Calcium, copper (II), iron (II), iron (III) and zinc.
Calcium- white, Copper (II)-blue, Iron (II)- sludgy green, Iron (III)-reddish brown, Zinc- white at first then colourless when more NaOH is added.
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How do you detect a carbonate?
Add dilute hydrochloric acid and a carbonate will fizz as it is giving off carbon dioxide. To test this use limewater and if it goes cloudy it is carbon dioxide.
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How do you detect a sulphate?
Add dilute hydrochloric acid and barium chloride (they hydrochloric acid is to get rid of any traces of carbonate ions as it would confuse your results). If it gives off a white precipitate it was a sulphate.
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How do you detect halides and what precipitates do chloride, bromide and iodide give off?
Add dilute nitric acid and silver nitrate. Chloride - white (silver chloride), Bromide- cream (silver bromide) and Iodide- yellow ( silver iodide)
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What is the lithosphere?
Earths rigid outer layer (the crust and part of the mantle below it). It contains silicon,oxygen and aluminium.
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What does carbon form?
Giant covalent structures such as diamonds and graphite
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What are the properties of a diamond?
The carbon atoms each form four covalent bonds, hardest natural substance, very high melting and boiling point, can't conduct electricity even when molten, is insoluble in water.
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What are the properties of graphite?
Each carbon atoms only forms three covalent bonds so the sheets of carbon atoms are free to slide over each other, useful as lubricant, layers are loose (used as pencils), high melting point, conducts electricity only 3 out of 4 electrons are used
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What giant covalent structure is sand made from?
Silicon dioxide- high melting point, doesn't conduct electricity.
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What is a metal ore?
A rock that contains varying amounts of minerals for which metals can be extracted.
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What is a common way of extracting a metal from its ore?
Reduction with carbon or carbon monoxide- when a metal oxide loses its oxygen it is reduced. Carbon gains the oxygen and is oxidised. Can only be used on metals that are less reactive than carbon e.g. zinc, copper, iron
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What is electrolysis?
Decomposition of a substance using electricity.Uses liquid to conduct electricity (normally a dissolved salt or molten ionic compound).
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How does electrolysis work for removing aluminium from its ore?
The positive aluminium ions are attracted to the negative electrode where they turn to neutral atoms and sink to the bottom. The negative oxygen ions are attracted to the positive electrode to become neutral and combine to form O2 molecules.
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What is the symbol equation at the negative electrode?
Al (small)3+ + 3e- = Al
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What is the symbol equation at the positive electrode?
2O(small)2- = O(small)2 + 4e-
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What is the complete symbol equation for the decomposition of aluminium oxide?
2Al(small)2O(small)3 (l) = 4Al (l) + 3O(small)2 (g)
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What is the structure of a metal?
Giant structure- metallic bonds have free electrons which come from the outer shell of every metal atom in the structure. The positively charged metal ions are held together in a crystal by a sea of free electrons that can move.
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What are the properties of metals?
They are good conductors of heat and electricity, strong and malleable (layers of atoms can slide over each other), generally have high melting and boiling points.
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What are the negative side of using ores?
Limited amount of them, use lots of energy, scars the landscape and destroys habitats. Also noise, dust and pollution care cause by an increase in traffic. Also deep mine shafts are dangerous even after they have been abandoned.
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What are the positive side of using ores?
Useful products can be made, provides jobs, brings money into an area which means that services such as transport and health can be improved.
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Why should we recycle metal?
Mining takes up a lot of energy which comes from burning fossil fuels, these are running out and contribute to acid rain, global dimming and climate change. Recycling uses less energy, saves money, limited amount of metals and cuts down on rubbish.
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Other cards in this set

Card 2

Front

Give an example of a molecular substance in the Earths atmosphere.

Back

Carbon dioxide or water

Card 3

Front

What are the properties of molecular substances?

Back

Preview of the front of card 3

Card 4

Front

What is covalent bonding?

Back

Preview of the front of card 4

Card 5

Front

Give an example of a single covalent bond and a double covalent bond.

Back

Preview of the front of card 5
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