3.2 Inorganic Chemistry Flashcards
What happens to atomic radius down the group?
It increases down the group as extra electron shells are added.
What is the trend in first ionisation energies going down group 2?
It decreases. Each element has one more shell so, shielding increases. So, outer electrons are further away from the nucleus and attraction is reduced. So, it’s easier to remove the outer electron.
What is the trend in reactivity down group 2?
It increases. When group 2 atoms react, they lose electrons and form positive ions. Down the group first ionisation energy decreases so, it’s easier to lose their electron so, they become more reactive.
What happens to the melting point of group 2 elements down the group?
Group 2 elements have metallic structure, with positive ions in a crystal structure surrounded by delocalised electrons. Down the group, metal ions get bigger. The electrons are farther away from the nucleus and feel less attraction. So, it takes less energy to break the bonds.
What reaction does beryllium undergo with water?
It doesn’t react with water.
How does magnesium react with water?
It reacts slowly to produce magnesium hydroxide. It reacts with steam vigorously.
What happens to the solubility of group 2 hydroxides down the group?
Solubility increases
Mg(OH)2- sparingly
Ca(OH)2- slightly
Sr, Ba- fully
What happens to the solubility of group 2 sulphates down the group?
It decreases.
BaSO4 is insoluble.
What is the use of acidified BaCl2?
The test for sulphates.
Add barium chloride and acidified hydrochloric acid and a white precipitate of barium sulphate will form.
Why can barium be dangerous?
It is toxic so soluble forms are very dangerous as they can be absorbed by the digestive system.
What is BaSO4 used for?
It is used as a contrast medium for x-rays. It’s safe as it is insoluble and cannot be absorbed by the bloodstream.
What are some of the other uses for group 2 compounds?
Mg(OH)2, CaCO3- used as an indigestion remedy.
Ca(OH)2, CaCO3- neutralises acidic soil.
CaO- used in flue gas desulfurisation. Removes SO2 from combustion waste.
Mg- used to extract titanium from the metal ore rutile.
Why is barium chloride acidified when used as a test for sulphate ions?
The addition of acid removes carbonate ions as carbon dioxide. Barium carbonate is also a white insoluble solid which would be indistinguishable from barium sulfate.
What happens to electronegativity going down group 7?
It decreases. Down the group, the shared pair of electrons gets further away from the nucleus as atomic radius increases. So shielding increases due to more inner electron shells.
What happens to melting and boiling point down group 7?
They increase. Larger atoms have more electrons so Van der Waals intermolecular forces become stronger.
Are halogens oxidising or reducing agents?
oxidising agents
What happens to the oxidising ability of the halogens down group 7?
It decreases. Down the group there is more shielding of the outermost electron. So, the attraction of the electrons to the nucleus becomes weaker and heavier atom is less likely to accept electrons.
What happens in the displacement reaction of a halogen?
In an aqueous solution, halogens react with halides to displace the least reactive one.
Are halides oxidising or reducing agents?
They’re reducing agents.
What happens to the reducing ability of the halides down the group?
It increases. Down the group, there is more shielding of the outermost electrons. The attraction of the electrons to the nucleus becomes weaker and the atom is more likely to lose electrons.
What is test 1 for the halide ions?
Add acidified AgNO3 and add dilute HNO3 to acidify the solution.
What would you observe when acidified AgNO3 is added to Cl- ions?
White precipitate
d.NH3- the precipitate redissolves
c.NH3- the precipitate redissolves
What would you observe when acidified AgNO3 is added to Br- ions?
Cream precipitate
d.NH3- no change
c.NH3- the precipitate redissolves
What would you observe when acidified AgNO3 is added to I- ions?
Pale yellow precipitate
d.NH3- no change
c.NH3- no change
What is the trend in solubility of the halide salts?
All halide salts are soluble except for silver halides. Which is why silver nitrate is used to test for halide ions.
What is test 2 for the halide ions?
Add concentrated sulfuric acid.
What would you observe when H2SO4 is added to Cl- ions?
The sulfuric acid isn’t reduced.
HCl (steamy white fumes), HNaSO4/Na2SO4
The hydrogen halide gas turns damp blue litmus paper red.
What would you observe when H2SO4 is added to Br- ions?
The H2SO4 is reduced
When reduced: Br2 (orange solution), SO2 (choking fumes)
When not reduced: HBr (brown fumes) , HNaSO4 / Na2SO4
The hydrogen halide gas turns damp blue litmus paper red
What would you observe when H2SO4 is added to I- ions?
The H2SO4 is reduced
When reduced: I2 (purple vapour), SO2 (choking fumes), S (yellow solid), H2S (rotten egg smell)
When not reduced: HI (steamy fumes) , HNaSO4 / Na2SO4
The hydrogen halide gas turns damp blue litmus paper red
Why is the silver nitrate acidified before testing for halide ions?
It gets rid of any soluble carbonate or hydroxide impurities.
Why is dilute and concentrated ammonia added after silver nitrate?
the colours of silver bromide and silver iodide precipitate are similar.
Why do we use chlorine in swimming pools even though it’s toxic?
The benefits to our health of water treatment by chlorine outweigh its toxic effects.
What is the use of chlorine in water treatment?
It is used to kill bacteria in swimming pools and drinking water, to prevent life-threatening diseases. The chloric acid formed in the reaction between chlorine and water is an oxidising agent and kills bacteria through oxidation and it’s also a bleach.
What happens when chlorine and water react in sunlight? What is the solution to this problem?
Hydrochloric acid is formed and chlorine is rapidly lost from the pool at the reaction isn’t reversible. So, pools need a frequent addition of chlorine. Instead, solid sodium chlorate is added.
What are the conditions for the reaction between sodium chlorate and water?
Swimming pool need to be kept slightly acidic as in an alkaline solution, the equilibrium of the reaction moves to the left and the HClO is removed as ClO- ions.
How is bleach formed?
Chlorine reacts with cold, dilute sodium hydroxide to from NaClO. This is also a disproportionation reaction.
What is the test for Mg2+ ions?
Add sodium hydroxide
Colourless solution to white precipitate
What is the test for Ba2+ ions?
Add sulfuric acid
Colourless solution to white precipitate
What is the test for NH4 + ions?
Add sodium hydroxide
Warm in a water bath
Turns damp red litmus paper blue
What is the test for OH- ions?
Add magnesium chloride
Colourless solution to white precipitate
What is the test for CO3 - ions?
Add nitric acid
Effervescence
What does fluorine look like in pure form?
Pale yellow gas
What does chlorine look like in pure form?
Pale green gas
What does bromine look like in pure form?
Dark red liquid
What does iodine look like in pure form?
Grey solid
What does fluorine look like in non-polar solvents?
N/a ( it reacts with solvents)
What does chlorine look like in non-polar solvents?
Pale green solution
What does bromine look like in non-polar solvents?
Orange solution
What does iodine look like in non-polar solvents?
Purple solution
What does fluorine look like in an aqueous solution?
N/a it reacts with water
What does chlorine look like in an aqueous solution?
Pale green solution
What does bromine look like in an aqueous solution?
Yellow/ orange solution
What does iodine look like in an aqueous solution?
Brown solution with grey solid
What is periodicity?
The repeating patterns of trends across and between periods.
Describe the reaction between sodium and water.
Sodium will react vigorously with cold water, forming a molten ball on the surface, fizzing and producing H2 gas. This reaction produces NaOH which is a strong alkaline solution.
Describe the reaction between magnesium and water.
It reacts very slowly with cold water and forms a weak alkaline solution. A thin coating of magnesium hydroxide coats the metal. Magnesium hydroxide isn’t very soluble so less OH- ions are released, making the solution weak. But, magnesium reacts much faster with steam.
What are the observations for the reaction between O2 and Na?
Yellow flame
White smoke/ solid
What are the observations for the reaction between O2 and Mg?
White flame
White smoke/ solid
What are the observations for the reaction between O2 and Al?
Bright white flame
White smoke/ solid
What are the observations for the reaction between O2 and Si?
White flame
White smoke/ solid
What are the observations for the reaction between O2 and P?
Burns spontaneously with a bright white flame and smoke.
What are the observations for the reaction between O2 and S?
Burns with a blue flame
What happens when chlorine is added to water?
It dissolves to form chlorine water.
What Ions are formed after the reaction between water and Na2O? What is the pH of the solution formed?
Na+, OH-
Strongly alkaline
13-14
What Ions are formed after the reaction between water and MgO? What is the pH of the solution formed?
Mg2+, OH-
Moderately alkaline
10
What Ions are formed after the reaction between water and Al2O3? What is the pH of the solution formed?
There’s so reaction, it’s insoluble.
What Ions are formed after the reaction between water and SiO2? What is the pH of the solution formed?
There’s no reaction, it’s insoluble.
What Ions are formed after the reaction between water and P4O10? What is the pH of the solution formed?
H3PO4: H+, PO4 ^3-
Strongly acidic
0-1
What Ions are formed after the reaction between water and SO2? What is the pH of the solution formed?
H2SO3: H+, SO3 ^2-
Weakly acidic
2-3
What Ions are formed after the reaction between water and SO3? What is the pH of the solution formed?
H2SO4: H+, SO4 ^2-
Strongly acidic
0-1
Why is the solution of Mg(OH)2 less alkaline than NaOH?
Mg(OH)2 is less soluble.
Why are sodium oxides and magnesium oxides bases?
They contain an O 2- ion which is a very strong base as it reacts with water to produce OH- and a strongly alkaline solution.
Why is sulfuric acid a stronger acid than sulfurous acid?
It fully dissociates in water.
What anion does SiO2 form?
SiO3 ^2-
(Silicate)
What are the characteristic properties of transition metals?
Complex formation
Formation of coloured ions
Variable oxidation state
Catalytic activity
How do the transition metals characteristic properties arise?
They have an incomplete d sub shell in atoms or ions
Which elements are classed as transition metals?
Ti - Cu
What is a ligand?
A molecule or ion that forms a coordinate bond with a transition metal by donating a pair of electrons.
What is a complex?
A central metal atom or ion surrounded by ligands.
What is coordination number?
The number of coordinate bonds to the central metal atom or ion.
What is a bidentate ligand?
A ligand that donates 2 pairs of electrons from 2 different atoms.
What are the 3 monodentate ligands?
H2O
NH3
Cl-
What are the similarities between the ligands NH3 and H2O?
They are similar in size and uncharged.
What happens to coordination number when NH3 ligands and H2O ligands are exchanged?
Coordination number remains unchanged.
What happens to coordination number when H2O ligands are replaced by Cl-?
There can be a change in coordination number as Cl- is larger than H2O.
Name a multidentate ligand.
EDTA 4-
What is Haem?
An iron (II) complex with a multidentate ligand.
What is the use of Haem in the body?
Oxygen forms a coordinate bond-ordinate bond to Fe(II) in haemoglobin, enabling oxygen to be transported in the blood.
Why is Carbon monoxide toxic? (Transition metals)
It replaces oxygen co-ordinately bonded to Fe(II) in haemoglobin.
What is the chelate effect?
When bidentate and multidentate ligands replace monodentate ligands from complexes. So, there is a large increase in disorder and entropy. (So, the reaction is more likely to be feasible.)
When are octahedral complexes formed?
With small ligands like H2O and NH3
What type of isomerism do octahedral complexes display?
They display cis-trans isomerism with monodentate ligands. (When they are in a 4:2 ratio)
They display optical isomerism with bidentate ligands.
When are tetrahedral complexes formed?
With larger ligands like Cl-
What type of isomerism do square planar complexes display?
Cis-trans isomerism
What is an example of a square planar complex?
(Cis and trans) Platin
Pt(Cl)2(NH3)2
Give an example of a linear complex.
[Ag(NH3)2]+ used in Tollens’ reagent
What are 2 examples of Bidentate ligands?
Ethane-1,2-diamine (NH_2CH_2CH_2NH_2)
Ethanedioate C2O4 ^2-
Why are transition metals characteristic complexes coloured?
The ligands cause the d orbitals to split
Wavelengths of visible light are absorbed causing e- to excite to a higher d-orbital
Other wavelengths of light are transmitted/reflected
(Absorption ∝ molar concentration)
How do you calculate the difference in energy between the ground state and excited state of the d e-?
E = hf
What factors affect the ΔE, and therefore colour, of transition metal complexes?
Changes in oxidation state
Co-ordination number
Ligand - size and type
What is the method for colourimetry?
Make up 5 standard solutions of known [].
Measure and record the absorbable of each.
Plot a graph of absorbable against []
Measure the absorbance of the unknown
Extrapolate the concentration of the unknown by reading the value off the graph.
What is a heterogeneous catalyst?
A catalyst in a different phase from the reactants and the reaction occurs at active sites on the surface.
What is a homogeneous catalyst?
A catalyst in the same phase as the reactants.
What are the 2 examples of heterogeneous catalysts?
V2O5 in the contact process
Fe in the haber process
How do you increase the efficiency of a heterogeneous catalyst?
Use a support medium to maximise the surface area of the catalyst and minimise cost.
What factor reduces the efficiency of a heterogeneous catalyst?
They can become poisoned by impurities that bind to them irreversibly and block the active sites. consequently, reducing efficiency which can have a cost implication.
Why are transition metals good catalysts?
Show variable oxidation states so they can act as intermediates in the exchange of e- between reacting species.
OR
Provide a surface for reactions to occur as the metal forms a weak bond to reacting species holding them in place.
Why are transition metals good catalysts?
Show variable oxidation states so they can act as intermediates in the exchange of e- between reacting species.
OR
Provide a surface for reactions to occur as the metal forms a weak bond to reacting species holding them in place.
Why is M^3+ more acidic than M^2+?
It is more polarising because it has a higher charge density. So, it polarises the OH bond in the water ligand so H+ ions are released.
Which transition metal complexes are amphoteric and why?
Metal hydroxides. As they dissolve in both acids and bases.
Name an example of an amphoteric metal complexes.
Hydroxides of Al3+
What are the observations and products when NaOH is added to Fe (II) dropwise and in excess?
Dropwise: Green solution -> green ppt
Fe(H2O)4(OH)2
Excess: No further change
What are the observations and products when NaOH is added to Cu (II) dropwise and in excess?
Dropwise: blue solution -> blue ppt
Cu(H2O)4(OH)2
Excess: no further change
What are the observations and products when NaOH is added to Fe (III) dropwise and in excess?
Dropwise: purple solution -> brown ppt
Fe(H2O)3(OH)3
Excess: No further change
What are the observations and products when NaOH is added to Al (III) dropwise and in excess?
Dropwise: colourless solution -> white ppt
Al(H2O)3(OH)3
Excess: white ppt -> colourless solution
[Al(OH)4]-
What are the observations and products when NH3 is added to Fe (II) dropwise and in excess?
Dropwise: green solution -> green ppt
Fe(H2O)4(OH)2
Excess: no further change
What are the observations and products when NH3 is added to Cu (II) dropwise and in excess?
Dropwise: blue solution -> blue ppt
Cu(H2O)4(OH)2
Excess: blue ppt -> deep blue solution
[Cu(H2O)2(NH3)4]^2+
What are the observations and products when NH3 is added to Fe (III) dropwise and in excess?
Dropwise: purple solution -> brown ppt
Fe(H2O)3(OH)3
Excess: no further change
What are the observations and products when NH3 is added to Al (III) dropwise and in excess?
Dropwise: colourless solution -> white ppt
Al(H2O)3(OH)3
Excess: no further change
What are the observations and products when Na2CO3 is added to Fe (II)?
green solution -> green ppt
FeCO3
What are the observations and products when Na2CO3 is added to Cu (II)?
Blue solution -> blue-green ppt
CuCO3
What are the observations and products when Na2CO3 is added to Fe (III)?
Purple solution -> brown ppt + effervescence
Fe(H2O)3(OH)3
What are the observations and products when Na2CO3 is added to Al (III)?
Colourless solution -> white ppt + effervescence
Al(H2O)3(OH)3
What are the observations and products when HCl is added to Cu (II)?
Blue solution -> yellow solution
[CuCl4]^2-
What are the colours observed when ammonium vanadate is reduced by zinc in acidic conditions?
Yellow solution -> blue solution -> green solution -> purple solution
