paper 1 memorise Flashcards
how does reactivity change in group 1?
reactivity increases as you go down
what happens when the first 3 alkali metals react with oxygen (O2)?
react rapidly as you go down, forms metal oxides
what happens when the first 3 alkali metals react with chlorine?
forms metal chloride e.g. sodium chloride
what happens when the first 3 alkali metals react with water?
see effervescence so gas is being produced, it forms an alkaline solution, forms metal hydroxide and hydrogen
what happens when chlorine, bromine and iodine react with non-metals?
forms covalent compounds e.g. hydrogen bromIDE
what happens when chlorine, bromine and iodine react with metals?
forms ionic compounds e.g. lithium bromIDE
what are the properties of transition elements?
- hard, strong
- high MP
- high density
- less reactive than group 1 with oxygen, chlorine and water
- can form ions with different charges
- can form coloured compounds
- are used as catalysts
explain ionic bonding
transferring electrons where the particles are oppositely charged ions
explain covalent bonding
the particles are atoms which share pairs of electrons
explain metallic bonding
the particles are atoms which share delocalised electrons
describe the structure of an ionic compound
it is a giant structure of ions, ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions which act in all directions in the lattice
what are the limitations of a state diagram?
in the model there are no forces, that all particles are represented as spheres and that the spheres are soli
what are the limitations of a dot and cross diagram?
do not tell the shape of the molecule
what are the advantages of a dot and cross diagram?
one atom’s electron is shown as a dot the other as a cross so its clear where each electron is coming from
what are the limitations of a stick diagram?
bonds are shown as sticks so no idea where electron is coming from, don’t show the outer electrons that are not in bonds, do not show the shape of the molecule
what are the advantages of a ball and stick diagram?
you can see the 3D structure
what are the limitations of a ball and stick diagram?
the ions are shown as widely spaced whereas the ions are packed together
what are the limitations of 3D diagram?
only show a small part of the lattice which can mislead that they are much smaller
why are metals are good conductors of thermal energy?
because energy is transferred by the delocalised electrons
describe the structure of 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
describe the structure of 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.
what is graphene?
a single layer of graphite
what is a fullerene?
molecules of carbon atoms with hollow shapes
what is the structure of fullerenes?
based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms. The first fullerene to be discovered was Buckminsterfullerene (C60 ) which has a spherical shape
what are carbon nanotubes?
cylindrical fullerenes with very high length to diameter ratios
what are carbon nanotubes useful for?
nanotechnology, electronics and to reinforce materials
what is graphene useful for?
electronics and composites
what are the properties of graphene?
- good conductor of electricity
- strong
- high MP/BP
what are fullerenes used for?
- drug delivery around the body
- lubricants as they can reduce friction between moving parts
- catalysts
what are the properties of carbon nanotubes?
- high tensile strength; can apply high stretching force before it breaks
- good conductor of electricity
- good conductor of heat
where are nanoparticles used?
deodorants, catalysts, sun creams
what are the risks of nanoparticles
they can absorbed by the body an enter cells and nobody knows the long term effects of it
what does the law of conservation?
that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants
what does Avogadro’s constant mean and what is its value?
the number of atoms, molecules or ions in a mole of a given substance is the Avogadro constant. The value of the Avogadro constant is 6.02 x 1023 per mole.
why isnt yield always 100%?
-the reaction may not go to completion because it is reversible
- some of the product may be lost when it is separated from the reaction mixture
- some of the reactants may react in ways different to the expected reaction
state the reactivity series
potassium sodium lithium calcium magnesium aluminium carbon zinc iodine lead hydrogen copper silver gold platinum
acronym: please stop laughing & calling me a careless zebra instead learn how cops save gold and platinum
how can metals less reactive than carbon can be extracted from their oxides?
by reduction with carbon
metal + water?
metal hydroxide + hydrogen
what does the reactivity of a metal depend upon?
its ability to lose electrons and form a positive ion
what happens when metals react in terms of ions?
they lose electrons to form a positive ion e.g. K -> K+ + e-
what is a base?
chemical which can neutralise acids producing a salt and water
what is an alkali?
bases that are soluble in water
what is the equation for neutralisation?
H+ + OH- -> H2O
acid + metal?
salt + hydrogen
what happens when the pH decreases by one unit?
the hydrogen ion concentration of the solution increases by a factor of 10
acid + metal oxide/hydroxide?
salt + water
define concentration
the amount of acid molecules in a given volume
why is electrolysis used for extraction?
if the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon
why are graphite electrodes used in the electrolysis of aluminium oxide?
they have a high melting point so we can use it at high temps without it melting
why is electrolysis expensive?
- a lot of energy is required to produce the electric current
- melting the compounds requires a lot of energy
for the electrolysis of solutions, what are the rules?
- at the cathode, the least reactive element is discharged which is hydrogen. exceptions: copper, silver, gold, lead
- at the anode a halogen is produced. if there isn’t one then oxygen is produced.
for electrolysis of solutions, what’s the half equation if oxygen is produced at the anode?
4OH- -> 2H2O + O2 + 4e-
for electrolysis of solutions, what is the half equation at the cathode is hydrogen is produced?
2H+ + 2e- -> H2
define activation energy
The minimum amount of energy that particles must have to react
define a cell
contain chemicals which react to produce electricity
what is The voltage produced by a cell depend upon?
the type of electrode and electrolyte
why can Rechargeable cells and batteries can be recharged
because the chemical reactions are reversed when an external electrical current is supplied
what is a key fact about cells?
the greater the difference between the reactivity of the metals, the greater the potential difference produced by the cell
define a battery
contains two or more cells connected in series to produce a greater voltage
what happens in alkaline batteries?
the reactants run out so no more electricity is being produced
what type of batteries aren’t rechargeable and why?
alkaline batteries as there isn’t a way to reverse the reaction
what is the half equation at the negative electrode for a fuel cell?
2H2 -> 4H+ + 4e-
what is the half equation at the positive electrode for a fuel cell?
O2 + 4H+ + 4e- -> 2H2O
what generally happens in a fuel cell?
hydrogen is being oxidised as 2H2 + O2 -> 2H2O
advantages of a fuel cell?
- produce electricity for as long as you provide hydrogen
- do not get less efficient the longer they run
- can be a source of drinkable water
what are the disadvantages of a fuel cell?
- they run on hydrogen gas which is explosive and difficult to store safely
- produce a relatively low pd so several are needed together
what are the advantages of a rechargeable battery?
- no dangerous fuels are required
- they produce a greater pd than fuel cell
what are the disadvantages of rechargeable batteries
- they run out and need to be recharged
- they store less electricity the more charging cycles they go through so they eventually need to be replaced
