Y1 Periodicity (I) Flashcards
How does the melting point of group 2 change down the group?
Melting point decreases down the group
- same charge
- atoms are much larger
- specific charge is smaller as charge is more diluted
- so less energy to break bonds
How does the pH of group 2 hydroxides change down the group?
pH increases down the group
- down group 2 atoms become larger
- more OH- ions per size ratio at the top of the group
- top ofthe group are better reductants
Group 2 hydroxides, which are better reductants?
Top of the group
Where is atomic radius the greatest?
bottom left of the periodic table
- (across) less protons, less nuclear charge
- (down) more shielding, outermost electron is further from the nucleus
Where is ionisation energy the greatest?
top right of the periodic table
Where is electronegativity the greatest?
top right of the periodic table
Reactivity of group two down the group?
Increases
Mg + steam
product: MgO + H2
instead of Mg(OH)2 +H2
reacts more vigorously with steam
Where are group 2 hydroxides more soluble?
Bottom of the group
Where are group 2 sulfates more soluble?
Top of the group
sulfate ion test explained
-add BaCl2 or Ba(NO)3 aqueous
- will form a white ppt when BaSO4(s) is formed
-Problem if CO3(2-) ions are present as will form also white BaCO3(s)
-either test for carbonates with dilute nitric acid (bubble through limewater will turn limewater cloudy) or add HCl to remove with effervescence
Sulfate ion test
- Add HCl to remove and carbonate (CO3(2-)) or sulfite (SO2(2-))impurities
-Add barium chloride solution - positive test if white ppt formed
Cabonate ion test
-Add HCl (or any acid)
- effervesence produced
- bubble through limewater
-positive result if limewater turns cloudy
Carbonate ion + acid
salt + carbon dioxide + water
Halide ion test
- Add nitric acid to remove and carbonate (CO3(2-)) or sulfite (SO2(2-))impurities
-Add silver nitrate
silver chloride - white ppt
silver bromide - cream ppt
silver iodide - yellow ppt
Silver nitrate test, tests for?
Halide ions
Barium chloride test, tests for?
Sulfates
Milk of magnesia is?
-Magnesium hydroxide Mg(OH)2
-Helps in digestion as it contains a suspension of the insoluble hydroxide (hence harmless)
-Neutralises the stomache acid and helps indigestion
What do you neutralise acidic soils with?
-Calcium hydroxide
-Ca(OH)2 + 2(H+) –> 2H20 + Ca(2+)
-H+ is acid
How do you neutralise flue gases?
- Have CaO or CaCO3 filter beds in the flue columns
- SO2 + CaO –> CaSO3 (IV)
- SO2 + CaCO3 –> CaSO3 + CO2
-the two compounds are known as lime and limestone - a slurry is a mixture of lime limestone and water
How would you describe group 2 elements?
Alkaline earth metals
kwjssn
what is calcium hydroxide known as?
slaked lime
The group two elements
beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).
What is a barium meal?
-Used in medicine
-a patient will swallow a cup of barium sulfate (s)
- the compund is opaque to xrays and so a structure of the persons digestive system will be able to be produced.
Along period 3 atomic radius…
Decreases
-increases proton number
-greater specific charge
-same shielding and distance from outer electron
Along period 3 electronegativity…
Inreases
-smaller radius
-atom has a stronger specific charge (to attract a lone pair of electrons in a covalent bond)
trend in ionisation energy along period 3
Increases
-as atomic radius decreases
Melting point of period 3 elements
Silicon the greatest, Argon the lowest
sodium flame test
bright yellow flame
Magnesium flame test
bright white light
Aluminium flame test
glowing bright white light
- oxide layer formed needs to be removed with NaOH to form aluminate Al(OH)4(-)
Silicon flame test
slow burn, orange glow
Phosphorous flame test
burns vigorously with pinkish white flame
sulfur flame test
Blue/ lilac flame
1) Chloride, silver nitrate test
2) add dilute ammonia
3) add conc. ammonia
1) white ppt (AgCl)
2) ppt redissolves
3) ppt redissolves
1) bromide, silver nitrate test
2) add dilute ammonia
3) add conc. ammonia
1) cream ppt (AgBr)
2) no change
3) ppt redissolves
1) iodide, silver nitrate test
2) add dilute ammonia
3) add conc. ammonia
1) yellow ppt (AgI)
2) no change
3) no change
calcium flame test
brick red flame
strontium flame test
red flame
barium flame test
pale green flame
copper flame test
green flame
test for ammonium ions (ammonia gas)
- ammonia is a base
- will turn red litmus paper blue
(want to produce ammonia gas faster? add NaOH)
Group 3 oxides trend in melting point
MgO (Giant ionic lattice greatest charge) greatest, SO2/SO3 (simple covalent molecule) is the lowest
In all flame tests what else is produced
white solid + smoky white fumes
Titanium extraction by sodium
- reduction of titanium (IV) chloride (TiCl4)
- forms titanium and sodium chloride
- done under inert argon gas at high temperatures
- dilute HCl used to remove NaCl
Titanium extraction by magnesium
- reduction of titanium (IV) chloride (TiCl4)
- forms titanium and megnesium chloride
- done under inert argon gas at high temperatures
Why can’t carbon be used for titanium extraction?
brittle titanium carbide would be produced
Why is titanium so expensive?
Titanium is expensive because it is awkward to extract from its ores, rutile (TiO2)
period 3 oxides trend in pH along the period
pH deacreases
- Na2O going to NaOH (pH 14)
- SO2 + H2O –> H2SO3 (IV) (pH 2-3)
- SO3 + H2O –> H2SO4(VI) (pH 0-1)
Magnesium oxide pH
- goes to magnesium hydroxide
- pH 9
sodium oxide pH
-goes to sodium hydroxide
- pH 14
why do aluminium oxide and silicon dioxide not have a pH
They are insoluble as they are giant lattices
What is the meaning of amphoteric?
Can act as both an acid and a base
Phosphor oxide pH
- P4O10 + 6H2O –> 4H3PO4 (pH 1)
Sulfur dioxide and sulfur trioxide pH
- SO2 + H2O –> H2SO3 (IV) (pH 2-3)
- SO3 + H2O –> H2SO4(VI) (pH 0-1)
Silicon dioxide + hydroxide
SiO2 + 2OH(-) –> SiO3(2-) +H2O
Phosphorous oxide + hydroxide
P4O10 +12H2O –> 4PO4(3-) +6H2O
Sulfur dioxide + hydroxide
SO2 + 2OH(-) –> SO3(2-) + H2O
Sulfur trioxide + hydroxide
SO3 + 2OH(-) –> SO4(2-) + H2O
Al2O3 and Al(OH)3 form ___________ when acting as acids
Aluminate ions
Al2O3 and Al(OH)3 being amphoteric and acting as a base and acid
What metals are used in a Catalytic Converter?
Platinum
Palladium
Rhodium
