C3 Flashcards
What did Newlands do in 1864?
He made the Law of Octaves,as he noticed every eighth element had similar properties. Therefore they were listed in rows of seven. However this messed up on the third row-as transition metals messed it up.
Why was Newland’s work on the Law of Octaves criticised?
His groups contained elements that didn’t have similar properties.
He didn’t leave any gaps for undiscovered elements.
He mixed up metals and non metals.
What did Dmitri Mendeleev do?
He put the elements into a table and left gaps to predict future elements,and to make sure elements with similar properties were in the same group.
What is the modern Periodic Table based on?
Electronic Structure.
What is the trend for Group 1 Alkali Metals?
The further down the group you go,the more reactive the metals are,as the outer electron is more easily lost-as it’s further from the nucleus. Also,the lower the melting and boiling point are.
They also form ionic compounds with non metals to lose an outer electron.
What does an Alkali metal produce when reacted with water?
Hydrogen Gas.
What happens when Lithium,Sodium or Potassium are put in water?
They react vigorously.
They float and move about the surface,fizzing.
They produce Hydrogen-and the potassium gets hot enough to ignite it.
They form hydroxides that dissolve in water to give alkaline solutions.
What is the trend for Group 7:The Halogens?
They are less reactive the further down you go,as its harder to gain an extra electron because the outer shell is further from the nucleus. They have a higher melting and boiling point the further you go down the group.
What are the similar properties of the Halogens?
All non metals with coloured Vapours.
Form Ionic bonds with metals,to gain an electron.
More reactive halogens will displace less reactive ones.
What are the properties of Transition Metals?
Good conductors of heat and electricity.
Dense,strong and shiny.
Less reactive than group 1 metals.
Have higher melting points than group 1 metals.
Why are compounds colourful?
Due to the transition metal ion they contain.
What do Transition Metals make?
Good catalysts.
What does Hard Water make?
Scum and Scale.
How is Scum made?
When dissolved magnesium and calcium ions in the hard water react with the soap.
How is scale formed?
When hard water is heated.
What is Hard Water caused by?
Calcium and Magnesium ions.
What are the benefits of Hard Water?
Calcium ions are good for healthy teeth and bones.
Less risk of heart disease.
How is temporary hardness removed?
By boiling. The calcium hydrogen carbonate decomposes to form calcium carbonate which is insoluble.
How can Hard water be turned Soft?
By running water through an Ion Exchange Column. They have lots of sodium ions,which are exchange for the calcium or magnesium ions that run through them.
How can Water be made suitable for drinking?
It passes through a mesh screen to remove big bits like twigs.
Chemicals are added to make solids stick together,and fall to the bottom.
Water is filtered through gravel beds to remove all solids.
Water is chlorinated to kill off any harmful microbes left.
What are the disadvantages of adding Chlorine and Fluorine to water?
Linked with certain cancers.
People can’t choose not to have it.
What does Equilibrium mean?
The amount of reactants and products will reach a certain balance and stay there. The forward and backward reactions will cancel each other out.
How do you move the position of Equilibrium?
By changing the temperature:
Raise-endothermic reaction will increase.
Lower-Exothermic reaction will increase to give out more heat.
By changing the pressure:
Raise-encourage the reaction with less volume.
Lower-The reaction with more volume.
What is the Haber Process?
Nitrogen + Hydrogen – Ammonia
What are the ideal industrial conditions for the Haber Process and why?
200 atmospheres of pressure-as needs to be set as high as possible to favour forward reaction,but not too high as it’ll be too expensive.
450 degrees Celsius,as yield of ammonia greater at lower temperatures. Compromise between highest yield and speed of reaction.
Iron catalyst speeds it up.
What is the functional group for Alcohols?
-OH
What are the similar properties of Alcohols?
Flammable
Dissolve completely in water to neutralise solutions.
What can alcohols be used for?
As solvents..
As fuels.
What is the functional group for Carboxylic acids?
-COOH
What are Carboxylic Acids used for?
To make soaps and esters.
Ethanoic acid can be dissolved in water to make vinegar.
How are Esters formed?
Alcohol + Carboxylic Acid = Ester + Water
What functional group for Esters have?
-C00-
How do you work out an Ester’s name?
Start of the alcohol,and the stand of the acid.
E.g Ethyl Ethanoate
What are the properties of Esters?
Smell nice
Flammable
Don’t mix well with water
Do mix well with solvents
What is the formula for Titration Calculations?
Concentration in mol/dm3 = moles / volume in dm3
How do you convert moles per dm3 into grams by dm3?
Number of moles= Mass / Relative Formula mass
What do you see in a Energy Level Diagram for an Exothermic Reaction?
The level of the products is lower than that of the reactants.
What do you see in an energy level diagram for an endothermic reaction?
The products are at a higher level than the reactants.
What lowers the activation energy?
Catalysts
What do Hydrogen and Oxygen give out when they react?
Energy
Why can Hydrogen Gas be used for?
Can be burnt to power cars.
What are Fuel cells?
An electrical cell that’s supplied with Fuel and an oxygen and uses energy from a reaction between them to generate electricity.
What doe Fuel Cells do?
Use fuel and Oxygen to produce electrical energy
In the early 1800s,what were the only two ways to categorise elements?
By their physical and chemical properties;
By their relative atomic mass
