Topic 4: Inorganic Chemistry Flashcards
From Original Flashcards - Not Updated
How do you measure atomic radius?
Half the distance between the two nuclei of the two identical atoms that are bonded together.
How does the atomic radius change across the period?
Decreases
Why does atomic radius decrease across the period?
More protons so an increased positive nuclear charge. So an increased attraction between the nucleus and the electrons. Drawing the electrons closer so a smaller atomic radius
What happens to atomic radius down the group?
Increases
Why does atomic radius increase down the group?
Number of electron shells increases, so that outer electron is further from the nucleus. Increased shielding from shells leads to decreased attraction to the nucleus and an increased atomic radius
What happens to the value of the first ionisation energy across the period?
Increases
Why does first ionisation energy increase across the period?
More protons means more attraction between the nucleus and electrons. So smaller ionic radius and greater attraction.
What happens to ionisation energy as you enter a new sub shell and why?
Drops as the new sub shell is of higher energy level so more energy is needed to remove.
on second filling the electrons are in opposite directions in same filling so repel one another
What happens to the ionisation energy value as you go down the group?
Decreases
Why does the Ionisation energy decrease down the group?
Atomic radius increases so electrons are further away from the nucleus and more shielding so attraction is less as you descend the group
What happens to the value of successive ionisation energies?
It increases
Why do successive ionisation energies increase?
when an electron is removed the other ones are pulled closer to the nucleus so more energy is needed to separate the electrons due to increased attraction.
What happens to successive ionisation energy as you drop an electron shell?
there is more attraction as you are closer to the nucleus so the ionisation energy increases
how do group 2 oxides react with acids?
Forms a salt and water
MgO + 2HNO3 -> Mg(NO3)2 + H2O
How do group 2 hydroxides react with acids?
forms the salt and water
Ca(OH)2 + H2SO4 -> CaSO4 + 2H2O
How does magnesium react with water?
Reacts with water as steam.
Forms magnesium oxide and hydrogen.
Mg + H2O -> MgO + H2
How do group 2 elements react with water?
Produces the metal hydroxide and hydrogen. Group 2 hydroxides can be soluble.
Sr + 2H2O -> Sr(OH) + H2
How does a group 2 element react with chlorine?
Forms the metal chloride.
Ca +Cl2 -> CaCl2
What is the general formula for metal chlorides?
XCl2
with x being the metal
How does a group 2 element react with oxygen?
Forms the metal oxides.
2Mg + O2 -> 2MgO
What colour do group 2 oxides burn?
Typically white.
Magnesium oxide is definitely white.
What happens to ionisation energy as you go down group 2? Why?
Ionisation energy decreases as the electron is further away from the nucleus and more shielding means less attraction.
What happens to reactivity as you go down group 2? Why?
Increases as it is easier to loose the two electrons due to the reduced ionisation energy
Are group 2 elements oxidising or reducing agents?
Reducing Agents.
They are oxidised themselves as they loose 2 electrons.
How do group 2 elements react with acids?
Produces metal salt and hydrogen gas.
Mg +H2SO4 -> MgSO4 + H2
What happens when an oxide reacts with water?
Produces a hydroxide, which dissolves in water.
CaO + H2O -> Ca(OH)2 + H2
What is the trend in solubility of group 2 hydroxides?
Increasingly soluble down the group.
Mg(OH)2 - Milk of magnesia, not very soluble.
Ca(OH)2 - Lime Water, very soluble
What effect do hydroxides have on the solution?
Makes the solution Alkali. The higher the hydroxide ion concentration the more alkaline it is.
what effect does solubility have on alkalinity?
Lower solubility means that there is a low concentration of hydroxide ions so is less alkaline.
What is the trend in solubility of group 2 sulphates?
Less soluble down the group.
MgSO4 - Highly soluble in water.
BaSO4 - Insoluble in water - forms a white precipitate
Are group 2 carbonates soluble in water?
No - Insoluble
Are group 2 nitrates soluble in water?
Yes - Soluble
What happens to the thermal stability of group 2 carbonates and nitrates as you go down the group?
Become more thermally stable.
Why do group 2 carbonates and nitrates become more thermally stable as you go down the group?
Carbonate and nitrate ions are larger so are more stable with larger ions found towards the bottom of the group.
Smaller ions are more polorising so cause more distortion to the Co or NO ion - making it easier to break bonds.
Larger ions are less polorising so more energy is needed to break the bonds.
is group 1 thermally stable?
Yes - Stable
How do group 1 nitrates decompose?
Norm nitrites (XNO2) and O2.
NaNO3 -> NaNO2 + O2
What is the exception to the group 1 carbonates and nitrates being stable?
Lithium Carbonate
Why is lithium carbonate an exception to the stability of group 1 carbonates?
Lithium is a small ion.
The carbonate forms lithium oxide and CO2.
The Nitrate forms lithium oxide, NO2 and O2.
Why do group 2 nitrates decompose more than group 1?
Group 2 has a greater positive charge (charge dencity). So group 2 ions are more polorising and cause more distortion to the nitrate ion.
Why is lithium the exception?
It is very small - meaning it has a large charge density - so polorises the anion more
What colour and state is Fluorine at RTP?
Pale yellow gas
What colour and state is chlorine at RTP?
Pale green gas
What colour and state is bromine at RTP?
red-brown liquid
What colour and state is iodine at RTP?
grey-black solid
How do melting and boiling points change down the group?
Increases down the group
Why does the melting and boiling point increase down group 7?
a greater number of london forces between the molecules as there are more electrons as you go dow the group
What is electronegitivity?
The ability of an atom to attract the bionding pair of electrons
How does electronegitivity change down group 7?
Decreases
Why does electronegitivity decrease down group 7?
Increased ionic radius so outer electrons are further from the nuclius - also increases sheilding. This reduces the attraction between the nuclius and the bonding pair of electrons
What happens when hallogens react?
They remove an electron from another species.
Causing the species to be oxidised
Are halogens oxidising or reducing agents?
Oxidising agents as they are reduced themselves
What happens when a halogen is reacted with an aqueous solution of another metal halide?
The more reactive halide displaces the halide of the metal halide.
Cl2 + 2NaBr -> 2NaCl +Br
What type of reaction is a halogen and aqueous solurion of a metal halide?
Displacement
What observations can be seen from a displacement reaction?
Colour change
What is the purpose of a non-polar organic solvent?
to distinguish between the different halides present.
What non-polar organic solvent is typically used to distinguish between different halides?
Cyclohexane
What colour is chlorine in water?
Pale green/colourless
What colour is chlorine in an organic solvent?
Pale Green/colourless
What colour is bromine in water?
Orange
What colour is bromine in an organic solvent
orange/red
What colour is iodine in water?
Brown
What colour is iodine in an organic solvent
pink/violet
What is a disproportionation reaction?
When the same element undergoes both oxidation and reduction simultaniouesly.
How does chlorine react with water?
Produces Chloric (I) acid and hydrochloric acid.
Cl2 + H2O -> HCl + HClO
How does chlorine react with cold aqueous sodium hydroxide?
produced sodium chloride (NaCl) and sodium chlorate (I) (NaClO) and water
Cl2 + 2NaOH -> NaCl + NaClO + H2O
How does chlorine react with hot concentrated sodium hydroxide?
Produces sodium chloride (NaCl). Also Water.
Chlorate (I) undergoes further decomposition and forms the chlorate (V) ion (NaClO3)
3Cl2 + 6NaOH -> 5NaCl + NaClO3 + 3H2O
What happens in the reaction between a halide and sulfuric acid?
The halide ions are oxidised. They cause sulpher to be reduced.
e.g.
2Br- + x -> Br2 + x-
What happens to group 7’s reducing ability as you go down the group?
Become better reducing agents
Why does the reducing ability of group 7 become better as you go down the group?
Small atomic radius and little shielding mean that it is hard for elements at the top to lose electrons.
What happens in the reaction with concentrated sulfuric acid and sodium chloride?
Makes Sodium Hydrogen sulphate and HCl.
NaCl + H2SO4 -> NaHSO4 + HCl
misty fumes of HCl are seen
What happens after the reaction of concentrated sulfuric acid and sodium chloride?
Chlorine ions have a low reducing power so the reaction stops. There is not change in oxidation states.
What happens in the reaction with concentrated sulfuric acid and sodium bromide?
Makes Sodium Hydrogen sulphate and HBr.
NaCl + H2SO4 -> NaHSO4 + HBr
See misty fumes of HBr followed by brown gas of bromine
What happens after the reaction of concentrated sulfuric acid and sodium bromide?
Bromine reduces the sulpher to form H2O, SO2 and Br2.
2Br- + H2SO4 + 2H+-> SO2 + Br2 + H2O
What happens in the reaction with concentrated sulfuric acid and sodium iodide?
Makes Sodium Hydrogen sulphate and HI.
NaCl + H2SO4 -> NaHSO4 + HI
See purple fumes of HI
What happens after the reaction of concentrated sulfuric acid and sodium iodide?
Iodine reduces the sulphur to an oxidation state of either 0 or -2. it forms either sulphur or hydrogen sulphate,
H2SO4 + 6HI -> 3I2 + 4H2O + S
or
H2SO4 + 8HI -> 8I2 + 4H2O + H2S
purple fumes of iodine are seen.
H2S produces an eggy smell
How can the produced halide solution be identified?
By adding silver nitrate (AgNO3) to the solution to cause the precipitation of a silver halide
What precipitate does AgCl produce?
White
What colour precipitate does AgBr produce?
Cream
What colour precipitate does AgI produce?
Yellow
How can the silver halide precipitate be tested to further aid identification?
Dissolving in dilute and concentrated ammonia
What does AgCl dissolve in?
Dilute ammonia solution
What does AgBr dissolve in?
Concentrated ammonia
What does AgI dissolve in?
Does not dissolve in ammonia
