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73 Cards in this Set
- Front
- Back
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How did chemists in the 19th century try to order elements? |
They attempted to order them based on their properties and atomic weights.
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What year did Newlands propose the law of octaves?
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1863 |
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What is the law of octaves?
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The law of octaves is the idea that every 8 eighth element in the periodic table (based on atomic weight) has similar properties.
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Why weren't Newlands ideas accepted?
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Because after Calcium the properties did not match very well within their groups.
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Who produced a better, more modern periodic table in 1869?
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Mendeleev
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How did Mendeleev go about creating his periodic table?
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He followed the law of octaves but left out spaces for elements yet to be discovered, so that the elements know fitted into the law. Later when new elements where discovered they matched his predictions.
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How is the modern periodic table ordered?
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In proton number order.
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Are groups vertical or horizontal?
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Vertical
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Are periods vertical or horizontal?
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Horizontal
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What determines the properties of an element?
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The number of electrons in the outer shell, which is also represented by the group number, generally.
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What is another name for Group 1 metals?
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Alkali Metals
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How are group 1 metals in terms of reactivity?
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Very reactive, with air and water.
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At room temperature, describe the state of matter, for group 1 metals.
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They are soft solids at room temperature.
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How many electrons do group one metals have in their outer shell?
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1
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What is the general formula for when group 1 metals react with water?
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Alkali + Water --> Alkali Hydroxide + Hydrogen
An example: Sodium + water --> Sodium Hydroxide + Hydrogen |
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What are transition elements?
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The metals found in the middle of the periodic table, which are all solid, bar mercury.
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What traits do transition metals share?
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Transition metals are all malleable, ductile, and good conductors of both heat and electricity. They are strong and dense.
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Do transition metals form positive or negative ions?
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Positive
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What is another name for Group 7 elements?
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Halogens
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How big are pure elemental molecule in group 7?
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Pairs. They are diatonic.
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At room temperature describe fluorine
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A pale yellow gas.
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At room temperature describe chlorine
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A green gas
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Describe bromine at room tempreture
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A red-brown liquid
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Describe iodine at room tempreture
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A grey solid. It is easily vaporised to a violet gas.
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What is hard water?
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Hard water is water that contains compounds such as calcium and magnesium salts.
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What is soft water?
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Soft water is pure(or close to) pure hydroxide.
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When hard water reacts with soap what forms?
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Scum
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How can temporary hard water be made soft?
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By heating it so that the ions it contains become an insoluble solid called scale.
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How can permanent water be made soft?
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By adding washing soda, where the sodium carbonate reacts to create solid calcium carbonate and magnesium carbonate. Another method is to use an ion-exchange column, which contains resin containing sodium or hydrogen ions, which causes the ions in the water to swap with these.
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What is scale?
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A insoluble solid created when temporary hard water is heated.
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What are the three main stages to water treatment?
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Find a suitable source, the remove the solids, before finally killing the microbes.
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The formula for energy transfer through a material
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Q =m*c*deltaT
Where Q is the amount of energy transfer in joules(J),m is the mass is grams, c is the specific heat capacity of that material in J/g Degrees Celcius, and deltaT is the temperature change in degrees celsius. |
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What is the specific heat capacity of water?
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4.2 J/g degrees celsius
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Endothermic Reaction
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A reaction that takes in energy
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Exothermic Reaction
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A reaction that releases energy
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When bonds are broken in a reaction do they release or take in energy to do so?
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They take in energy making them endothermic.
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How does a catalyst increase the rate of reaction?
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It lowers the activation energy by providing a different path(or set of steps) to break/make bonds and create a product, using less energy, normally using an intermediate product.
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Why is hydrogen a good fuel?
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It burns easily and releases a lot of energy per gram, as well as only releasing water upon combustion.
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What are some disadvantages of hydrogen as a fuel?
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It is hard to store or supply and has safety problems.
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When lithium reacts with sodium hydroxide, what colour flame is produced?
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Crimson
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When sodium reacts with sodium hydroxide, what colour flame is produced?
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Yellow
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When potassium reacts with sodium hydroxide, what colour flame is produced?
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Lilac
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When calcium reacts with sodium hydroxide, what colour flame is produced?
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Red
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When barium reacts with sodium hydroxide, what colour flame is produced?
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Green
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What is the test for carbonate ions?
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Add dilute hydrochloric acid to the solution. If it fizzes and turns milky the substance has carbonate ions.
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What is the test for Halide ions?
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Add dilute nitric acid and then silver nitrate solution.
Chloride ions will give a white precipitate; bromide ions, a cream precipitate; and iodide ions will produce a yellow precipitate. |
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What is the test for sulfate ions?
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Add dilute HCL and then barium chloride solution. If a white precipitate forms sulfate ions are in the solution.
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Titeration
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A method used to accurately measure how much acid and alkali are needed to react together completely.
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End point of a reaction
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The point where an acid-base reaction is complete.
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Describe in detail the steps required to perform a titration.
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A pipette is filled with alkali, using a pipette filler normally to 25 centimetres cubed. This is then emptied into a conical flask which will have a few drops of a suitable indicator added to it.
Acid is then put into a burette and the starting volume of acid is read against the scale. You then let the burette run swirling the conical flask to get a rough estimate of how much acid is required to neutralise the alkaline (which is done by subtracting the volume of acid used from the starting amount.) You then repeat the process, this time putting in acid until the roughly the point where it neutralises, and you then start adding drops and swirling after each drop to get a more accurate result. The reaction is complete when the indicator is clear. |
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What is the major equation in titration?
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N = C * V
Where N is the number or moles, C is the concentration in moles/l and V is volume in litres. To work out values for acids or alkaline you line them up and rearrange the equation until all the data is obtained. |
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Dynamic Equilibrium
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In a closed system this is a reaction in which the rate of the forward reaction is equal to the rate of the reverse reaction.
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What is Chaterlier's principle?
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Chaterlier's principle states that whatever is done to an equilibrium the equilibrium will move to oppose the change.
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When a system is at equilibrium, how do you make more product?
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You can remove product or add more reactant.
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If the forward reaction of a system produces more molecules of gas, what does an increase in pressure do?
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It decreases the amount of product formed.
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If the forward reaction of a system produces less molecules of gas, what does an increase in pressure do?
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Increases the amount off product formed.
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If the forward reaction of a system is exothermic and the temperature increase, what happens?
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The amount of product produced decrease.
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If the forward reaction of a system is endothermic and the temperature increases, what happens?
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The amount of product produced increase.
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What are the steps required to make ammonia?
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1) Gas stream containing hydrogen and nitrogen flows into the bulb.
2) The mixture is compressed to a pressure of 200 atmospheres and heated to 450 degrees Celsius. 3) The compressed and heated mixture then flows into a vessel containing an iron based catalyst. 4) The mixture of gases emerging from the reactor is cooled. Ammonia liquefies and is separated. 5) Unreacted nitrogen and hydrogen are returned to the reaction vessel via the compressor. |
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What is ammonia used for?
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Fertilizers and other chemicals.
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What is the reaction for amonia?
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N_2 (g) + 3H_2 (g) <--> 2NH_3 (g)
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What is the average yield for the Haber process?
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15%
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What is the functional group for an Alcohol and how is it bound?
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OH ( + a hydrocarbon)
The last Carbon atom in the hydrocarbon has two bonds to two hydrogen and has a bond to O which has a bond to H. |
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What is the functional group for a Carboxylic Acid and how is it bound?
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COOH (+ a hydrocarbon)
The last Carbon atom in the hydrocarbon has bond to the previous carbon atom in the chain and a double bond to an oxygen atom and a single bond to OH. |
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What is the functional group for an Ester and how is it bound?
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COO- (+ a hydrocarbon)
Similar to a Carboxylic Acid the last Carbon atom has a bond to the carbon atom before it in the chain, as well as a double bond to oxygen. It is also bound to another oxygen which is bound to the start of another hydrocarbon chain. |
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What is homologous series?
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A group of molecules that have a general formula, for example alkanes and alkenes.
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What are some uses of alcohol?
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Ethanol is used in alcoholic drinks. They are used for fule and are turned into carboxylic acid. The smaller molecules react with water to produce neutral solutions.
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What happens when carboxylic acid dissolve in water?
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They produce a solution with a pH value of less than 7. Salt and water are also produced.
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What's distinct about an ester?
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They are volatile and often have distinct smells.
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Strong Acid
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Acids that ionise completely in aqueous solutions, meaning that their is no acid left.
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Weak Acid
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Acids that do not ionise completely in aqueous solutions, meaning some of it is left in the solution
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In aqueous solutions of equal concentration, how are weak acids different form strong acids.
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Weak acids have a higher pH and react more slowly.
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Aqueous solution
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The mixture made by adding a soluble substance to water.
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