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83 Cards in this Set

  • Front
  • Back
Why is the periodic table called the periodic table?
Similar properties of elements occur at regular intervals
Who attempted to classify the elements by arranging them in order of their atomic weights?
Newlands, and then Mendeleev
The columns in which elements with similar properties are organised is called
Groups
Why was Newland's periodic table not accepted by other scientists?
It was incomplete and since the elements were ordered in atomic weight this made some elements being placed inappropriately
How did Mendeleev overcome the problems faced by Newland?
He left gaps for the elements that he thought had not been discovered yet
The modern periodic table is arranged by
Atomic (proton) number
Elements in the same group have the same
Number of electrons in their outer shell
Properties of Group 1 elements: (5)
All alkali metals
Low density
React with non metals to form ionic compounds with a charge of +1; these compounds are white solids which dissolve in water to form colourless solutions
React with water, releasing hydrogen
Form hydroxides which dissolve in water to form alkaline solutions
In Group 1, the further down the group an element is: (2)
The more reactive the element - because electrons are more easily lost as the number of shells increases
The lower its melting and boiling point
Compared with elements in Group 1, transition metals: (3)
Have higher melting and boiling points (except mercury)
Are stronger and harder
Are much less reactive as they do not react as vigorously with water or oxygen
Properties of transition metal ions: (3)
Can form different charges
Form different coloured compounds
Useful catalysts
The elements in Group 7 of the periodic table are known as
Halogens
Halogens react with metals to form an ionic compound in which the halide ion carries a charge of
-1
In Group 7, the further down the group an element is: (2)
The less reactive the element - because electrons are less easily gained
The higher the melting and boiling point
What type of water readily forms lather with soap?
Soft water
Hard water reacts with soap to form scum and so more is needed
What does not form scum with hard water?
Soapless detergents
What does hard water contain? Why?
Magnesium and calcium ions which comes from being in contact with rocks
What is the difference between permanent and temporary hard water?
Permanent hard water remains hard when boiled whereas temporary hard water becomes soft once boiled
What does temporary hard water contain?
Hydrogencarbonate ions (HCO3-)
These decompose on heating to form carbonate ions which react with the calcium and magnesium ions to form precipitates
What are the disadvantages of hard water? (2)
Can increase costs as more soap is needed
Produces scale when heated which reduces the efficiency of kettles
What are the advantages of hard water? (2)
The calcium compounds in it are good for the development of bones and teeth
Can also reduces heart disease
How can hard water be softened? (2)
By removing the calcium and magnesium ions which can be done by:
Adding sodium carbonate which forms a precipitate of calcium carbonate and magnesium carbonate
Using a water softener which uses ion exchange columns containing sodium or hydrogen to replace the magnesium and calcium
Why may chlorine be added to drinking water?
Reduce the number of microbes
Why may fluorine be added to drinking water?
To help dental health
What is done to tap water to help improve the taste and quality?
Pass them through filters which contain carbon, silver and iron exchange resins
How can pure water be made and what are the disadvantages of it?
Distillation - evaporating and then condensing
Lots of energy is needed to evaporate the water and so pure water is expensive to make and buy
What does calorimetry measure?
The amount of energy released when a substance is burnt
How can calorimetry be done?
Burning the fuel underneath water in a glass or metal container
The amount of heat energy released =
the mass of water heated x 4.2 x change in temperature of the water
The amount of heart energy released (Q) is measured in
Joules (J)
The mass of water heated (m) is measured in
Grams (g)
c in the equation Q=mcT refers to
the energy required to raise the temperature of 1g of water by 1C (4.2)
The change in temperature of the water (T) is measured in?
Celsius (C)
What reactions would the calorimetry method be used for? (2)
Solids with water
Neutralisation reactions
Breaking bonds and forming bonds requires
Energy
In an exothermic reaction
The energy released from forming new bonds if greater than the energy needed to break existing bonds
In an endothermic reaction
The energy released from forming new bonds is less than the energy needed to break the existing bonds
Catalysts
Provide a different pathway for chemical reactions which need a lower activation energy
Why is hydrogen burned (in air)?
To use as a fuel in combustion engines or fuels cells which produce electricity
What flame colour is a result of lithium compounds?
Crimson
What flame colour is a result of sodium compounds?
Yellow
What flame colour is a result of potassium compounds?
Lilac
What flame colour is a result of calcium compounds?
Red
What flame colour is a result of barium compounds?
Green
Aluminum, calcium and magnesium ions + hydroxide solution ->
White precipitates
(Only aluminium hydroxide precipitate dissolves in excess sodium hydroxide solution)
Copper 2 + sodium hydroxide solution ->
Blue precipitate
Iron 2 + sodium hydroxide solution ->
Green precipitate
Iron 3 + sodium hydroxide solution ->
Brown precipitate
Carbonate + dilute acid ->
Carbon dioxide + salt + water
How can we test for carbon dioxide
Turns limewater cloudy
Chloride ions + silver nitrate solution ->
Silver chloride - which is a white precipitate
Bromide ions + silver nitrate solution ->
Silver bromide - which is a cream precipitate
Iodide ions + silver nitrate solution ->
Silver iodide - which is a yellow prepitate
Sulfate ions + barium chloride solution + dilute hydrochloric acid ->
White precipitate
Concentration of solution =
Number of moles of solute/ volume of solution
What is the concentration of a solution measured in?
Moles/dm^3
What is the volume of solution measured in?
Dm^3
Titration
Finds out how much of an acid and alkali is needed to neutralise each other (using an indicator)
What raw materials are used in the Haber process?
Nitrogen and hydrogen
How is the nitrogen and hydrogen used in the Haber process obtained?
Nitrogen is taken from the air
Hydrogen is from natural gas
How is ammonia made?
Purified nitrogen and hydrogen are passed over a catalyst of iron at 450C (high temperature) and 200 atmospheres (high pressure). The gases react to form ammonia. As it cools the ammonia liquefies and is then removed, the remaining hydrogen and nitrogen are recycled
Nitrogen + hydrogen -><-
Ammonia
Equilibrium
Reactions occur at the exactly same rate in each direction
If the temperature is raised in an endothermic reaction the yield
Increases
If the temperature is decreased in an endothermic reaction the yield
Decreases
If the temperature is raised in an exothermic reaction the yield
Decreases
If the temperature is decreased in an exothermic reaction the yield
Increases
Why will a raise in temperature favour the endothermic reaction?
Endothermic reactions require heat energy
In gaseous reactions, an increase in pressure will favour the reaction that produces
The least number of molecules
What is the functional group and general formula of alcohols?
-OH
CnH2n+1OH
What is the functional group of carboxylic acids?
-COOH
What us the functional group of esters?
-COO-
Alcohols, carboxylic acids and esters are all
Organic compounds containing carbon hydrogen and oxygen
What are the first three members of the alcohols?
Methanol
Ethanol
Propanol
Properties of methanol, ethanol and propanol (3)
Dissolves in water to form a neutral solution
Reacts with sodium to produce hydrogen
Burns in air
Uses of alcohols
Solvents, fuel and alcoholic drinks
Ethanoic acid is the main acid in
Vinegar
Alcohol + oxygen ->
Carbon dioxide + water
Alcohol + oxidising agent ->
Carboxylic acid + water
Properties of carboxylic acids
Dissolve in water to produce acidic solutions
React with carbonates to produce carbon dioxide
Do not ionise completely when dissolved in water and so are weak acids
Carboxylic acid + alcohol -><-
Ester + water
Ethanol + ethanoic acid ->
Ethyl ethanoate
Uses of esters
Perfumes and food flavourings because of their smells