Alkali Group 2 Metals and halogens Flashcards
What is the trend in group 2 metals going down the periodic table in atomic size
The atomic size increases as going down group 2 as the number of outer shells increases
What is the trend for in first ionisations energy in group 2 elements going down the group
First ionisation energy decreases going down group 2 as the outer shells are more shielded from the nucleus by the inner electrons so they are held less closely and so are easier to remove
What is the trend in electronegativity going down group 2
Electronegativity decreases as the outer shells are shielded from the nucleus and so the attraction reduced
State the trend in melting points of elements going down group 2
The melting points of the elements decrease going down group 2 as the attraction between the cations and delocalised electrons decreases due to atom getting bigger
What is produced when MG reacts with steam and give the equation
Mg+2H20->Mg(oh )+H2
It reacts with steam
Give the equations for when strontium and barium react with cold water
Sr+2H2O->Sr(OH)+H2
Ba+2H2O->Ba(OH)+H2
State the trend in solubitly of sulphates in group 2 and give the most soluble and insouble
Solubility of sulphates decreases going down group 2
I.e. Ba(+2) + SO4-BaSO4
MgSO4 is soluble and SrSO4 and BaSO4 are insoluble
What two alkali metals don’t react with water and which one react with steam
Be and Mg
Mg reacts with steam
What is produced when Ba reacts with sulphate ions
Thick white precipitate (barium meal)
How would u test for sulphate ions
Add barium chloride,dilute HCL and the unknown solution
If a white precipitate forms sulphate ions are present
When testing for sulphate ions why is HCL added
To remove other ions like hydroxide ions and carbonate ions as they may affect the test
State the solubility of hydroxides in group 2
Solubility increases going down group 2
Mg+2 OH->MgO+ H2
Ca+2H2O->Ca(OH)2+H2
What can magnesium hydroxide be used for
As it’s almost insouble it’s used in milk of magnesia for indigestion
What is calcium hydroxide used for
In slaked lime in order to neutralise acidic soil
What is barium sulphate used for
It’s used in a barium meal in the gut where it can absorb x rays and it’s completely insouble
Give the order of electronegativity in group 7 from highest to lowest
F
Cl
Br
I
Give the order of the strongest oxidising agents in group 7
F
Cl
Br
I
Why does oxidising power increase going group 7
As their are fewer number of shells in the atom,so electrons are closer to the nucleus and are less shielded,this means the attraction of electrons to the nucleus is stronger and so the atom is more likely to accept electrons
State the trend in reducing power going down group 7 and why
Reducing power increases with iodine being the strongest reducing agent as the atom gets larger so the outer electrons are further away from the nucleus and so less attracted
What is meant by displacement reactions
This is when halogens that are the strongest oxidising agent wil displace more reactive halides(reducing agents)
What happens when chlorine displaces both bromine and iodine and give the equations
CL2 +2Br- ->2CL- +Br2 and orange colour will appear
CL2 +2I->2Cl- +I2
And a brown colour will appear
What happens when bromine displaces iodine
Br2+2I–>2Br- +I2
A brown colour will appear
What is seen when Cl is reacted with H2SO4 and state the type of reaction it is
White fumes of HCL are produced
The fumes will turn blue litmus paper red
Acid base reaction
What is produced with Bromine reacts with H2SO4 and state what happens to the sulphuric acid
Red colour of bromine
White fumes that can turn litmus paper red
HBR is made
Sulphuric acid is reduced to sulphur dioxide +6 to +4
Bromine Increases from -1 to 0
What is produced when iodine reacts with H2SO4 and state what happens to the sulfur
White fumes that will turn blue litmus paper red
Purple colour or iodine
Smell of rotten eggs due to H2S
Sulfur reduced from +6 to -2
H2SO4 reduced to H2S
In reactions with the halides what does the concentrated sulphuric acid behave as
An oxidising agent
When reacted with sliver ions and nitric acid state the precipitates formed when reacted with halide ions
Chlorine will produce a white precipitate
Bromine a cream precipitate
Iodine a yellow precipitate
AgNo3 +Br- -> AgBr
Why is nitric acid added
To ensure that an hydroxide ions or impurities are removed
State how we can distinguish between the precipitate that halide ions form and give the reactions with each halide ion
We add ammonia
If dilute or conc ammonia is added to AgCl the precipitate will dissolve
If conc ammonia is added to Agbr the precipitate is soluble
AgI is insouble in conc ammonia
Give the equation when chlorine reacts with water and state the type of reaction it is
CL2 +H20->HCL +HClo
It’s disproportionation as the chlorine is simultaneously oxidised and reduced
Give advantages and disadvantages of using chloride acid
It kills Bactria in Pools
It’s toxic and can cause cancer
Why isnt dilute HCL or H2SO4 used to acidify silver nitrate
They would give off different precipitates
Ie sliver sulfate will form and sliver chloride which invalidates the test
H2SO4 forms white precipitate of sliver chloride that will invalidate the test
What is the use of Cao(caoh)
To remove So2 from flue gas in a process called neutralisation
State why magnesium is used instead to extract titanium instead of carbon
As titanium reacts with carbon to form another product so it’s reacts with carbon and chlorine first
State why magnesium is used instead to extract titanium instead of carbon
As titanium reacts with carbon to form another product so it’s reacts with carbon and chlorine first
Give the equation for the reaction of mg and ticl4
TiCl4+2Mg-Ti+2MgCl2
What happens when cold dilute chlorine is added to sodium hydroxide and give the equation
Sodium chlorate forms which is used as bleach
2NaOH+CL2-> NaClO +Nacl +H2O
What do both the reaction of chlorine with water and naoh have in common
They are both disproportionation reacts in which chlorine is simultaneously reduced and oxidised
