The periodic table and energy part 2 Flashcards
A more reactive halogen…..
A more reactive halogen will oxidise and displace a less reactive halogen this is called a displacement reaction
What is the colour of …. in water
A, chlorine
B, Iodine
C, Bromine
A, Pale Green
B, Brown
C, Orange
What is the colour of …. in cyclohexane (organic compound)
A, Chlorine
B, Iodine
C, Bromine
A, pale green
B, Violet
C, Orange
Displacement reaction ionic equations
Cl2(aq) + 2Br-(aq) = 2Cl-(aq) + Br2(aq)
Cl2(aq)+2I-(aq)=2Cl-(aq)+I2(aq)
Br2(aq)+2I-(aq)= 2Br-(aq)+ I2(aq)
What is a disproportionate reaction
this is a reaction in which the same element is both reduced and oxidised
What does chlorine do in water
chlorine kills bacteria and makes the water safer the drink
What is done to chlorine when it reacts with water
both oxidised and reduced
Write out the equation of the reaction of chlorine and water
Cl2(aq)+H20(l)= HClO(aq)+ HCl(aq)
write out the equation of the reaction of chlorine with cold dilute aqueous NaOH
Cl2(aq)+2NaOH(aq)=NaCl(aq)+NaClO(aq)+H20(l)
what are the benefits and cons of adding chlorine to water
\+Kills bacteria \+ gets rid of waterborne diseases - chlorine is a toxic gas - chlorine reacts with organic matter to form chlorinated hydrocarbons these can cause cancer - ethical as people not given choice
What holds the metal together
- BETWEEN CATIONS (positive ions in a fixed position in the lattice) AND DELOCALISED ELECTRONS (in the outer shells)
in a giant metallic lattice…..
delocalised electrons are spread throughout
electrons can move within the structure
charge must balance over the whole structure
- ARE ALL METALS
what is the difference between covalent and metallic structure
covalent - electrons are localised
metallic - electrons are delocalised
What are the properties of giant metallic lattices
- high melting and boiling points
this means that the electrons are free to move but positive ions are fixed, the attraction between positive ions and negative delocalised electrons are strong, high temperatures are needed to overcome the bonds - good electrical conductivity
this is because the delocalised electrons can move freely within the metallic lattice this allows the electrical charge to flow - malleability and ductability
malleable - can be hammered into different shapes
ductile - can be drawn out or stretched
Describe the trend in melting point across the period
between group 1-14 melting points increase steadily, elements have giant structures and it increases each successive group as its nuclear charge increases as does the number of electrons in the outer shell causing a stronger attraction each successive element group has more electrons to form more covalent bonds
between groups 14-15 there is a sharp decrease in its melting point, elements have simple molecular structure so have weak London forces
between elements group 15-18 the melting points are low as elements have a simple molecular structure
LOOK AT THE TABLE ON PAGE 118
NO LIKE SERIOUSLY LOOK AT IT, SCAR IT IN TO YOUR MIND NOW
Structure and bonding of diamond
form giant covalent
each carbon atoms form 4 other carbon atoms around it
high melting and boiling points
structure and bonding of graphite
for giant covalent
layers of carbon atoms
delocalised electrons
strong and light
structure and bonding of silicon dioxide
giant covalent
What is a qualitative test
tells you which ions are present but not how much of each ion
what does a qualitative test involve
involved a precipitation reaction from 2 aqueous solutions in which an insoluble solid forms, it is carried out on a small scale
Describe the test for carbonate ions (negative ions)
add a dilute strong acid (H+) to the suspected carbonate solution
collect any gas that is formed and pass it through lime water
If the colourless gas is formed shown by fizzing and bubbles and it turns limewater cloudy then a carbonate is present in the solution
test for carbonate ions equation
CO32-(aq)+2H+=H20(L) + CO2(g)
Describe the test for sulfate ions (negative ions)
add dilute hydrochloric acid and barium chloride to the suspected sulfate ion. then a white precipitate of barium sulfate is produced
write the equation for sulfate ions
Ba2+(aq)+SO42-(aq)= BaSO4(aq)
What doe sulfate ions and barium sulfate ions react to form
sulfate ions react with barium ions to form an insoluble salt called barium sulfate
Describe the test for halide ions (negative ions)
dissolve suspected halide in to water then add aqueous silver nitrate, note the colour of any precipitate formed, if colour is hard to distinguish then add dilute aqueous ammonia then concentrated, note the colour and solubility of the precipitate in the aqueous ammonia
silver chloride - white precipitate and soluble dilute ammonia
silver bromide - cream precipitate soluble in concentrated ammonia
silver iodide - yellow precipitate and insoluble in concentrated and dilute ammonia
write the ionic equations for halide reactions
Ag+(aq) + Cl-(aq) = AgCl(s)
Ag+(aq) + Br-(aq) = AgBr(s)
Ag+(aq) + I-(aq) = AgI(s)
describe the test for ammonium ions
add sodium hydroxide solution to the suspected ammonium compound and warm, test for any gas with red litmus paper
ammonia gas will turn red litmus paper blue, ammonia gas has a very distinct smell
bubbles will form
write the equation for ammonium ion test
NH4+(aq) + OH-(aq) = NH3(aq) + H2O(aq)
Describe Graphene
- Giant covalent lattice
- interlocking hexagonal rings
- strong and light
- can conduct electricity
- used in nanotechnology as its one atom thick
How do trends in ionisation energy support the Bohr model of the atom
- Bohr model describes a positive nucleus with negatively charged electrons orbiting it
- supported by successive ionisation energies
- the jumps in ionisation energies tell us the electrons and the electronic structure
Group 2 reacting with oxygen equation
2Mg(gas) + O2(gas) = 2MgO
Group 2 reacting with water equation
Mg(s) + 2H2O(l) = Mg(OH)2(aq) + H2(g)
Group 2 reacting with dilute acids equation
Mg(s) + 2HCl (aq) = MgCl2 + H2
2nd ionisation energy of group 2
Be+(g) = Be2+(g) + e-
what is the correct order to carry out tests
- carbonates
- this is addition of acid so will no affect the sulfate or halides tests - sulfate
- must come after carbonates because BaCO3 can form which can confuse results - halides
- last test as this forms AgNO3 which will form a precipitate with carbonates and sulfates so needs to be carried out last
