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How did Mendeleev organize his own version of the periodic table?
He left gaps which allowed for undiscovered elements to be predicted.
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How was the periodic table organized during the early 1800's?
By atomic mass.
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Which chemist created the octave system of organizing elements?
John Newland.
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Why did early 1800's chemists arrange the period table by atomic mass?
They had yet to discover atomic structure or subatomic particles.
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When did Dimitri Mendeleev create his table of elements?
1869.
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What is the modern period table based on?
Atomic Structure.
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What subatomic particle is set out in shells?
Electrons.
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If the nucleus is further away from the outermost shell, is the force of attraction greater or smaller?
Smaller.
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When the force of attraction between a nucleus and the outer shell is reduced by inner electrons, what is this phenomena called?
Shielding.
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Why do group-7 elements get less reactive when going down the group?
Increased distance and shielding mean that there is less attraction from the nucleus pulling electrons.
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When you go down the group 1 elements, do they become more or less reactive?
More reactive.
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What happens to the melting and boiling points of group 1 elements as you go down the group?
Lower melting and boiling points.
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Do alkali metals have a high or low density?
Low.
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How many outer electrons do the alkali metals have?
One.
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When alkali metals react with water, what do they produce?
Hydrogen gas.
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What happens to the reactivity of the halogens when you go down their group?
They become less reactive.
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What happens to the melting and boiling points of halogens when you go down the group?
The melting and boiling points increase.
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Halogens all of coloured vapours. What colour corresponds with each element?
Yellow Gas.
Green Gas.
Red-Brown Liquid.
Purple Vapour.
- Flouride.
- Chloride.
- Bromide.
- Iodine.
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What bonds do halogens form with metals?
Ionic Bonds.
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What happens when more reactive halogens react with less reactive ones?
The more reactive halogen will displace the less reactive one.
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What properties do transition metals have?
- Good conductors of heat and electricity.
- Dense, strong, shiny.
- Less reactive than group 1 metals.
- Denser, stronger, harder than group 1 metals.
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Can transition metals have more than one ion? If so, give two examples.
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Transition metals form colourful compounds. Match the colours to the element.
Yellow
Purple
Blue.
Green.
- Potassium chromate.
- Potassium maganate.
- Copper sulphate.
- Copper.
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Do transition metals make for good catalysts? Give two examples.
- Yes.
- Iron is used in the Haber Process.
- Nickel is used for turning oils into fats.
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Where are the transition metals on the periodic table?
Between Group 2 & Group 3.
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What does hardwater create? How are these made?
- Scum - Formed when trying to lather soap in hard water.
- Scale - Calcium carbonate during boiling water.
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What ions must be removed to make hard water soft?
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What positive effects does hard water have?
- Less risk of developing heart disease.
- Calcium is good for teeth and bones.
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How would you carry out a titration?
- Fill a burette with 50 cubic cm of soap solution.
- Add 50 cubic cm of water into a flask.
- Use the burette to add 1 cubic cm of soap solution to the flask.
- Put a bung in the flask and shake for 10 seconds.
- Repeat steps 3 and 4 until a lather is formed.
- Record how much soap was needed then repeat steps 1-6.
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How does an ion exchange column work?
They contain sodium and hydrogen ions that are exchanged for calcium or magnesium ions.
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What salts make water poisonous?
Phosphates and nitrates.
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Where does most drinking water come from?
Reservoirs.
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How is water treated?
- The water is passed through a mesh to clear up large debris.
- Chemicals are added to make solids and microbes stick together.
- The water is filtered through gravel beds to remove all solids.
- Water is then chlorinated to kill off bacterium.
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What disadvantages are there to adding fluoride and chlorine to water?
- Chlorine in drinking water can potentially increase the risk of cancers.
- Chlorine can react with other chemicals to produce toxic by-products.
- Fluoride can cause cancer in large doses.
- Ethical concerns with mass medication.
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How is pure water made?
By distilling it.
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What is a reversible reaction?
A reversible reaction is one where the products of the reaction can themselves react to produce the original reactants.
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When a reversible reaction occurs in a closed system, what state will be reached?
Equilibrium will be reached.
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What is equilibrium?
The state where the amount of reactants and products reach a balance and stay there.
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What happens when the temperature changes in a reversible reaction?
- Raising the temperature will cause the endothermic reaction to use up the extra heat.
- Reducing the temperature will cause the exothermic reaction to give out more heat.
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What happens when you change the pressure in a reversible reaction?
- Increasing the temperature will encourage the reaction that produces less volume.
- Decreasing the pressure will encourage the reaction that produces more volume.
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What does a catalyst do to a reversible reaction?
A catalyst speeds up both the forwards and backwards reactions by the same amount.
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What functional group do alcohols have?
-OH.
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What is the general formula of Alcohols?
CnH2n+1OH.
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What are alcohols used for?
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What properties do the first three alcohols share?
- Flammable.
- Dissolve in water.
- React with sodium to give hydrogen and alkoxides.
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