Studied by 0 peoplebehaviour of particles in a solid
have a fixed shape and cannot flow, because their particles cannot move from place to place
cannot be compressed (squashed), because their particles are close together and have no space to move into
behaviour of particles in a gas
flow and completely fill their container, because their particles can move quickly in all directions
can be compressed, because their particles are far apart and have space to move into
why can transition metals be used as a catalyst
they have a variety of different charged ions
anything using temp changes, what can you use as a control to improve accuracy
polystryene cup
what shape is Buckminster fullerene molecule
spherical
uses of fullerenes
drug delivery - hollow
hydrogen storage
antioxidants
catalysts (high sa to vol ratio)
lubricants ( spherical so will roll)
why does sodium oxide have a high melting point
giant structure strong forces of attraction pulling them together lots of energy needed to break them
what do you need to mention in practical questions
Control variables
Risk factors; solution
Independent variables
Method w/ instruments
Evaluative conclusion
Dependent variables
what's the difference between electrolysis and chemical cell
electrolysis uses electricity, chemical cell uses a chemical reaction
meaning of accuracy
the degree to which the result of a measurement, calculation, or specification conforms to the correct value or a standard
meaning of precision
refinement in a measurement, calculation, or specification, especially as represented by the number of digits given
how are soluble salts made
by reacting a dilute hydrochloric acid with an insoluble solid
give two limitations of this simple particle model for hydrogen gas
it doesn’t show movement
they r not 2d irl
1 mega joule = how many j
1,000,000
structure of a diamond
In diamond, each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure, so diamond is very hard, has a very high melting point and does not conduct electricity
why does a diamond have a high MP
Diamond has a very high melting point because a large amount of energy is needed to overcome the many strong covalent bonds.
why does a diamond conduct no electricity
It does not conduct electricity as there are no delocalised electrons in the structure.
what is the structure of graphite
In graphite, each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings which have no covalent bonds between the layers.
In graphite, one electron from each carbon atom is delocalised.
(graphite is similar to metals in that it has delocalised electrons.)
structure of graphene and how this makes it useful
Graphene is a single layer of graphite and has properties that make it useful in electronics and composites.
structure of carbon nanotubes
Carbon nanotubes are cylindrical fullerenes with very high length to diameter ratios. Their properties make them useful for nanotechnology, electronics and materials.
A different student produced a pure, dry sample of copper chloride using the same reaction.
How should the solution be heated gently in step 3; “Heat the solution gently until crystals start to form.”
using a (boiling) water bath or using an electric heater
state the law of conseration of mass
mass of products = mass of reactants
explain why the student should use a pipette to measure the dilute sulfuric acid and a burette to measure the sodium hydroxide volume
pipette measures a fixed volume (accurately)
burette measures variable volume
why is sodium chloride a strong electrolyte
The solution will have the maximum number of ions available to conduct electricity.
equation for a hydrogen fuel cell
2H2 + O2 ⟶ 2H2O
in refreence to bond energies, explain why something would be an exothermic reaction
energy released forming (new) bonds is greater than energy needed to break (existing) bonds
(so) energy is released (to the surroundings)
half equation for the reaction occurring at an electrode in 1 type of hydrogen fuel cell
H2 + 2OH− → 2H2O + 2 e−
why would a feul cell be described as an alkaline cell
contains OH− ions
how to find out how many protons there are
small #
how to find out how many neutrons there are
big number - small number
properties of the alkali metals (GROUP 1 METALS)
are soft (they can be cut with a knife)
have relatively low melting points
have low densities
Give two differences between the properties of iron and sodium.
• iron has a higher MP/BP
• iron is dense(r)
• iron is hard(er)
• iron is strong(er)
• iron is less reactive
• iron has ions with different charges
• iron forms coloured compounds
• iron can be a catalyst
Chadwick’s experimental work on the atom led to a better understanding of isotopes.
Explain how his work led to this understanding.
Chadwick provided the evidence to show the existence of neutrons
(this was necessary because) isotopes have the same number of protons
but with different numbers of neutrons
what should you do when listing methods
independent, dependent, control,
when identifiying problems for 2&3 markers what should you do
identify the problem
give a solution
in graphite, each carbon forms _____ (covalent) bonds
3
The student made an error in selecting the apparatus for this investigation. How should the apparatus be changed?
use measuring cylinders, or gas syringes (instead of test tubes)
(Because) test tubes cannot measure the volume
Name the products formed when chlorine solution reacts with potassium iodide solution.
potassium chloride and iodine
Chlorine reacts with hydrogen to form hydrogen chloride.
Explain why hydrogen chloride is a gas at room temperature.
hydrogen chloride is made of small molecules
so has weak intermolecular forces
that require little energy to overcome
Give one reason why it would be hazardous if water came into contact with sodium
• very exothermic reaction
• produces a corrosive solution
• produces hydrogen, which is explosive / flammable
Explain why you would not expect titanium chloride to be a liquid at room temperature
metal chlorides are usually ionic
solid at room temperature / have high melting points
due to them having strong (electrostatic) forces between the ions
why is graphite used for electrodes in electrolysis
its unreactive, can conduct electricity
what is a neutralisation reaction
A neutralisation reaction is a reaction between an acid and a base. Acids in solution are sources of hydrogen ions , H. + alkalis in solution are sources of hydroxide ions, OH.
write the ionic equation for the neutralisation reaction of hydrochloric acid with potassium hydroxide
H+ + 0H- → H2O
what is the ammonia from the Haber process used for
nitrogen based fertilisers
what does an ester bond look like
meaning of affinity
Affinity is the tendency of a chemical species such as an atom or molecule to react with another to form a chemical compound.
how did mendeleev organise the elements
arranging them in order of their atomic weight
what did mendie do with his version of the periodic table
had gaps in it
showed elements with similar chemical properties lined up in groups
properties of g7 metals
simple molecules
coloured vapours
diatomic molecules
form ionic salts w metals
form molecular compounds with non metals
characteristics of transition metals
form coloured compounds
catalytic properties
ions w different charges
what’s the modern name for atomic weight
relative atomic mass
formula of molecule X in group 7
X2
Describe what you would see when sodium reacts with chlorine.
flame
white precipitate
Calcium hydroxide solution reacts with an acid to form calcium chloride. Complete the word equation for the reaction
hydrochloric (acid) water
Suggest one reason why it costs less to use nanoparticles rather than fine particles in suncreams
• less can be used (for the same effect)
• greater surface area (to volume ratio)
uses of nanoparticles
catalyst
electronics
deoderant
sun creamal
Give one limitation of using a dot and cross diagram to represent an ammonia molecule.
does not show the shape or only two-dimensiona
Hydrogen fuel cells can be used to power different forms of transport. Some diesel trains are being converted to run on hydrogen fuel cells.
A newspaper article referred to the converted trains as the new ‘steam trains’. Suggest why.
(in a fuel cell) hydrogen is oxidised (to produce water)
water is produced / released as gas / vapour / steam
Explain why a mixture is used as the electrolyte instead of using only aluminium oxide
mixture has a lower melting point (than aluminium oxide)
(so) less energy needed
Explain why sodium chloride solution cannot be used as the electrolyte to produce sodium metal.
hydrogen (gas) would be produced (instead of sodium)
(because) sodium is more reactive than hydrogen
Explain why the excess hydrogen must be burned off.
to prevent hydrogen escaping (into the air)
(because) hydrogen is explosive
John Dalton; Before the discovery of the electron, atoms were thought to be …..
tiny spheres that could not be divided.
John Dalton The discovery of the electron led to the ….
plum pudding model of the atom.
The results from the alpha particle scattering experiment led to….
nuclear model replaced the plum pudding model
how did the alpha particle scattering experiment change the model
Most alpha particles went straight through the foil. But a few were scattered in different directions.
the mass of an atom is concentrated at its centre, the nucleus
the nucleus is positively charged
Niels Bohr adapted the nuclear model by suggesting that ….
electrons orbit the nucleus at specific distances. The theoretical calculations of Bohr agreed with experimental observations.
physical properties of group 1 elements
soft
low mp
malleable
not useful as cataylyst
physical properties of transition metals
they are good conductors of heat and electricity.
high mp
dense
strong
what kind of cup should you use for investigations that measure temp
polystyrene
what do labels x and y rep
(X) energy (Y) (overall) energy change
why is it suitable for drug delivery
hollow
unreactive
non toxic
high sa to vol ratio
why is the solid in excess rather than the liquid
excess) zinc oxide can be filtered off
the noble gases have boiling points that increase going down the trt/f
true
Give one reason why the products are difficult to separate if magnesium is used to reduce silicon dioxide.
both products are solid
what does higher strength of an acid mean
• the stronger an acid the greater the ionisation / dissociation (in aqueous solution) • (so) the stronger the acid the lower the pH
what does higher conc of an acid mean
• the higher the concentration of an acid the more acid / solute in the same volume (of solution)
• (so) the higher the concentration of the acid the lower the pH
why is there no electrical conductivity in barium sulphate
there are no ions that are free to move (
because) barium sulfate is solid / insoluble
(and) hydrogen ions have reacted with hydroxide ions to produce water
which are in the same period
m &q
electrolysis materials
behaviour of particles in a liquid
flow and take the shape of their container, because their particles can move around each other
cannot be compressed, because their particles are close together and have no space to move into
how can the atom economy of a reaction be improved
find a use for the waste
change reaction to reduce waste
why does iodine have a higher bp than chloring
the FORCES between iodine molecules are stronger
why does potassium iodide conduct electricity
it contains IONS which are free to move
why is X positioned in group Y of the periodic tablle
it has Y outer electrons
how can ionic compound conduct electricity when molten
IONS are free to move
saftey precautions when heating contents in an evaporating dish
wear googles
what is the half equation for what happens at the negative electrode in fuel cells (anode)
2H2 → 4H+ + 4e–
what is the half equation for what happens at the positive electrode in fuel cells (cathode)
4H+ + O2 + 4e– → 2H2O
what is the total equation for what happens in hydrogen fuel cells
2H2 + O2→ 2H2O
what is meant by a strong acid
fully ionised when disolved in water
to form h+ ions
how does a covalent bond hold atoms together
the positive nuclei from two different atoms are held together by their common attraction for the shared pair of electrons held between them.
how does an ionic bond hold atoms together
strong electrostatic forces of attraction between the oppositely charged ions. The forces act in all directions in the lattice. This is called ionic bonding .
Note
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