4. inorganic chem and periodic table (as) Flashcards
group two IE down group + reactivity
IE decreases down group
extra electron shell
inner shell shield outer e from attraction of nucleus
reduces electrostatic attraction between nucleus and outer e
easier to remove outer e
,, reactivity increases down group
group 2 reaction w water: metal + water
= metal hydroxide + hydrogen
group 2 metals burn in oxygen
metal burns in oxygen forms
metal + oxygen
solid white oxides formed
group 2 reacts with chlorine
metal + chlorine
forms solid white chlorides
oxides of group 2 metals react with water to form
metal hydroxides which dissolve the hydroxide ions make solutions strongly alkaline
what is an exception as a base as g1 and g2
magnesium oxide and beryllium oxide
oxides and hydroxides are
bases
because oxides and hydroxides are both bases they will
neutralise dilute acids forming salts
oxides as you go down the group
form more strongly alkaline solutions because hydroxides get more soluble
oxides reaction w water
MO + H2O
metal hydroxides formed
M(OH)2
oxides reaction with dilute acids
MO + 2HCl
form salt and water
MCl2 + H2O
hydroxides reaction with water
M(OH)2 + H2O
metal hydroxides
M(OH)2
hydroxide reaction w dilute acids
m(OH)2 + 2HCl
salt + water
MCl+ 2H2O
solubility trends depend on
compound anion
compounds of group 2 elects contain… and what does it do
singly charged negative ions
it increases in solubility down the group
compounds that contain doubly charged negative ions
decrease solubility down the group
hydroxides of group 2 elements and their solubility order
least soluble: magnesium hydroxide
calcium hydroxide
strontium hydroxide
most soluble: barium hydroxide
sulfates and their solubility of group 2 elements
most soluble: magnesium sulphate
calcium sulphate
strontium sulphate
least soluble: barium sulphate (insoluble)
thermal decomposition def
when a substance breaks down when heated
the more thermally stable a substance is …
the more heat it will take to break it down
carbonate and nitrates are large negative ions (anions) and can be unstable by
positively charged ions (cations) and they polarise the anion, and distorts it
the greater the distortion what happens to the compound
the less stable the compound
large cations cause
less distortion than small cations because they have lower charge density
charge density def
the areas covered by the charge of of an ion
thermal stability down a group
thermal stability increases
what happens down a group and link to thermal stability
down the group the larger the cations ,, the lower the charge density ,, less distortion caused ,, more stable the carbonate and nitrate compound
group 2 compounds are what thermally stable than group 1 compounds
less thermally stable
explain the diff in g1 and g2 compounds and their thermal stability
g2 less thermally stable because
greater charge greater distortion ,, less stable the compound
g2 causes +2 charges ,, less stable
group 1 carbonates thermal stability
thermally stable- can’t make them decompose w a bunsen burner
group 1 nitrates thermal stability
decompose to form nitrogen and oxygen
group 2 carbonates thermal stability
decompose to from oxide and carbon dioxide
group 2 nitrates thermal stability
form oxide, nitrogen dioxide, and oxygen
how to test thermal stability of nitrates
.measure how long it takes until certain amount of oxygen produced
. how long it takes until an amount of brown gas (nitrogen dioxide) produced but in a fume cupboard because it’s toxic
how to test carbonates
. how long it takes to produce carbon dioxide using limewater
lithium colour flame
red
sodium flame colour
yellow
potassium flame colour
lilac
rubidium flame colour
red
caesium flame colour
blue
calcium flame colour
brick red
strontium flame colour
crimson
barium flame colour
green
how to do a flame test
- mix small amount of compound w a few drops of HCl
- heat a piece of nichrome/ platinum wire in a bunsen flame to clean it
- dip wire into compound/ acid mixture
- hold into flame + note colour produced
explanation of flame colour test
.energy absorbed from flame causes electron to move to higher energy levels
. colours seen are electrons falling back down to lower energy levels releasing energy in form of light
fluorine colour + physical state at room temp
pale yellow
gas
chlorine colour + physical state
green and gas
bromine colour and state
red brown and liquid
iodine colour and physical state
grey and solid
halogens solubility in water explained
low solubility in water because they’re non polar
chlorine colour in water and hexane
water- colourless
hexane- colourless
bromine colour in water and hexane
water- yellow/orange
hexane- orange/ red
iodine colour in water and hexane
water- brown
hexane- pink/violet/purple
electronegativity down the halogens
decreases down the group
halogens reactivity down group explains
reactivity decreases
. atoms is large down the group ,, outer e further from nucleus ,, more shielded ,, less electronegative ,, reactivity decreases
melting and boiling points down the halogens group
. increase down group
increase electron shells ,, more electrons ,, more London forces are stronger between molecules
more london forces ,, harder to overcome intermolecular forces ,, mp increases
displacement reactions def
a reaction wheee one element replaces another element in a compound
what ions can chlorine/ fluorine/ iodine displace
Cl: Br ion + I ion
Br: I ion
I:
displacement reaction between halogens and halides in a redox reactions
displaced element is oxidised and displacing element is reduced
potassium chloride solution reaction w chlorine water
no reaction
potassium chloride solution reaction with bromine water
no reaction
potassium chloride solution reaction with iodine solution
no reaction
potassium bromide reactions w chlorine water
bromine produced and chlorine ion produced
potassium bromide reaction w bromide water
no reaction
potassium bromide reaction w iodine water
no reaction
potassium iodide solution reaction with chlorine water
iodine atoms produced and chlorine ion
potassium iodide solution reaction w bromine water
bromide ion + iodine atom
potassium iodide solution reaction w iodine water
no reaction
if bromine formed then what colours formed
orange
if iodine formed what colour will be present
brown
when halogens reacts
they’re reduced
when halogens react with cold alkalis they
undergo disproptionation
what is produced when I2 + 2NaOH—>
(sodium iodate) NaOI + NaI + H2O
chlorine and sodium hydroxide reacts to produce
bleach
2NaOH (aq) + Cl2 (g) —>
(sodium chlorite) NaClO (aq) + NaCl (aq) + H2O (l)
when you mix chlorine w water ( cl2 + h2o) it produces
HCl+ HClO
hydrochloric acid + hypochlorous acid
hypochlorous acids ionises to make chlorate (I) ions that kill bacteria ,, adding chlorine to water makes water safe to drink
reducing power of halides down a group
increases down a group
KF/ KCl reaction with H2SO4 (sulphuric acid)
KHSO4 (s) + HF (g)
KHSO4 + HCl
KBr + H2SO4
.—> KHSO4 (s) + HBr (g)
. 2HBr (aq) + H2SO4 —> Br (g) ( orange fumes) + SO2 (g) + 2H2O
KI + H2SO4 —>
KI(s) + H2SO4 —> KHSO4 (s) + HI(g)
2HI (g) + H2SO4 —> I2 + SO2 (g) + 2H2O (l)
6HI(g) + h2so4 (g) —> s (s) + 3I2 (s) + 4H2O (l)
8hi + h2so4 arrow 4i2 + h2s + 4h2o
h2s gas smells of rotten eggs
hydrogen halides are
acidic gases - colourless gasss
hydrogen halides can dissolve in water and produce
misty fumes of acidic gas ( turn damp litmus paper blue to red)
hydrogen chloride/ bromide / iodide forms
hydrochloric acid
hydrobromic acid
hudroiodic acid
hydrogen halides ( HCl) + ammonia gas ( NH3) react to produce + what type of reaction
NH4Cl ammonium chloride ( white fumes)
acid base reaction
test for halides
- add dilute nitric acid
- silver nitrate solution
colours of halides precipitate formed after
AgF- no peecipitate
AgCl- white peecipitate
AgBr- cream peecipitate
AgI- yellow peecipitate
1 AgCl 2 AgBr 3 AgI reactions with dilute ammonia solution
1- precipitate dissolves in ammonia solution to give a colourless solution
2- precipitate remains unchanged if dilute ammonia solution added ,, colourless solution
3- peecipitate does not dissolve even in concentrates ammonia solution
carbonates test
- add dilute HCl
,, carbon dioxide produces run through limewater
sulfates test
- add dilute HCl
- add barium chloride solution
white peecipitate will be formed
test for ammonium compounds
- add sodium hydroxide and heat gently
- use a damp red litmus paper will turn blue if ammonia present
why do we add concentrated HCl to metal compounds in flame tests
conc HCl would produc chlorides and this would increase volatility and ,, better colour produced
sulfate ions test + false
positive
add nitric acid drops
add barium chloride
white precipitate formed
nitric acid is used to neutralise solution if carbonates present to prevent a falsie positive
