How did Mendeleev organize his own version of the periodic table?
He left gaps which allowed for undiscovered elements to be predicted.
How was the periodic table organized during the early 1800's?
By atomic mass.
Which chemist created the octave system of organizing elements?
Why did early 1800's chemists arrange the period table by atomic mass?
They had yet to discover atomic structure or subatomic particles.
When did Dimitri Mendeleev create his table of elements?
What is the modern period table based on?
What subatomic particle is set out in shells?
If the nucleus is further away from the outermost shell, is the force of attraction greater or smaller?
When the force of attraction between a nucleus and the outer shell is reduced by inner electrons, what is this phenomena called?
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.
When you go down the group 1 elements, do they become more or less reactive?
What happens to the melting and boiling points of group 1 elements as you go down the group?
Lower melting and boiling points.
Do alkali metals have a high or low density?
How many outer electrons do the alkali metals have?
When alkali metals react with water, what do they produce?
What happens to the reactivity of the halogens when you go down their group?
They become less reactive.
What happens to the melting and boiling points of halogens when you go down the group?
The melting and boiling points increase.
Halogens all of coloured vapours. What colour corresponds with each element?
What bonds do halogens form with metals?
What happens when more reactive halogens react with less reactive ones?
The more reactive halogen will displace the less reactive one.
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.
Can transition metals have more than one ion? If so, give two examples.
Transition metals form colourful compounds. Match the colours to the element.
- Potassium chromate.
- Potassium maganate.
- Copper sulphate.
Do transition metals make for good catalysts? Give two examples.
- Iron is used in the Haber Process.
- Nickel is used for turning oils into fats.
Where are the transition metals on the periodic table?
Between Group 2 & Group 3.
What does hardwater create? How are these made?
- Scum - Formed when trying to lather soap in hard water.
- Scale - Calcium carbonate during boiling water.
What ions must be removed to make hard water soft?
What positive effects does hard water have?
- Less risk of developing heart disease.
- Calcium is good for teeth and bones.
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.
How does an ion exchange column work?
They contain sodium and hydrogen ions that are exchanged for calcium or magnesium ions.
What salts make water poisonous?
Phosphates and nitrates.
Where does most drinking water come from?
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.
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.
How is pure water made?
By distilling it.
What is a reversible reaction?
A reversible reaction is one where the products of the reaction can themselves react to produce the original reactants.
When a reversible reaction occurs in a closed system, what state will be reached?
Equilibrium will be reached.
What is equilibrium?
The state where the amount of reactants and products reach a balance and stay there.
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.
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.
What does a catalyst do to a reversible reaction?
A catalyst speeds up both the forwards and backwards reactions by the same amount.
What functional group do alcohols have?
What is the general formula of Alcohols?
What are alcohols used for?
What properties do the first three alcohols share?
- Dissolve in water.
- React with sodium to give hydrogen and alkoxides.