Topic 4 Periodic table Flashcards
what do water and group 2 metal react to form
metal hydroxides
What is the reaction between magnesuim & water like
reacts very slowly + bubbles of hydrogen gas form
what can be seen in the reaction of G2 metal with water
- As you go down the group the level of bubbling, effervecence & vigour increase
what is the model reaction of G2 metals with water
M + 2H2O = M(OH)2 + H2O
what does calcuim form in the reaction with water
white precipitate
what does Sr form in the reaction with water
Colourless solution
what does Ba form in the reaction with water
Colourless solution
what do G2 metals form when they react with oxygen
metal oxides
what is the model equation of the reaction of G2 metal with oxygen
2M + O2 = 2MO
what is formed when G2 metal react with chlorine
Metal Chlorides
what is the model equation for the reaction of G2 metals with chlorine
M + Cl2 = MCl2
what is the observation in the reaction between G2 metals and chlorine
a yellow glow can be seen
what happens in the reaction between magnesuim & steam
Reacts very vigourously
what is formed with magnesuim is reacted with steam
Magnesuim Oxide
What is formed when G2 oxides react with water
Metal Hydroxides
What happens to the alkalinity of the G2 hydroxides as you go down the group
Become more alkaline as there is more OH being dissolved
what are formed when G2 oxides are reacted with acids
Salt (either sulphate or chloride)
Water
what happens when G2 hydroxides are reacted with acids
forms colourless solution of metal salts
what happens to the solubility of G2 hydroxides as you go down the group
increase
what happens to the solubility of G2 sulphates as you go down the group
decrease
what can be used as test for sulpahtes
adding HCL & baruim chloride to form baruim sulphate which is a white precipitate
what is thermal decomposition
breakdown of a compound into 2 or more different substances using heat
what is formed in the TD of G2 carbonates
Group 2 Carbonates breakdown via thermal decomposition to form metal oxides and carbon dioxide.
what happens to G2 carbonates as you go down the group and what is required
Going down the group, the carbonates become more stable, and more heat is needed to break them.
what is formed in the TD of G2 nitrates
Group 2 nitrates undergo thermal decomposition to form metal oxide, nitrogen dioxide and oxygen.
how does each of the products of the TD of G2 nitrates look like
The group 2 nitrates are white solids, the metal oxide is also a white solid. Nitrogen dioxide is a brown gas
what is one precaution that must be taken in the TD of G2 nitrates
Since nitrogen dioxide is toxic, the thermal decomposition of nitrates take place in a fume cupboard.
what happens to G2 nitrates as you go down the group and what is required
The nitrates become more stable down the group and so require more heat.
what happen during thermal stability reaction
when carbonate/nitrate ion is placed near positive G2 ion the G2 ion attracts the delocalised electrons towards itself. The carbonate/nitrate ion becomes polarized which then weakens the C-O bond. If this is heated then the CO2 breaks free and forms a metal oxide
how the reaction between carbonate ion & G2 cation change as you go down the group
- As you go down the group the size of ion increases which decreases the charge density.
- The ability to polarize the carbonate ion decreases
- The C-O bond in the carbonate ion is weakened less
what does TD of G1 nitrate form
- Metal Nitrate
- Oxygen
what happens in the TD of G1 carbonate
- Decomposition won’t take place as they require high temperaturs
which element is an exception for the pattern of the TD of G1 nitrates and what does it form
- Lithuim
- Forms Metal Nitrate, Nitrogen dioxide and oxygen
what are the 3 steps to flame test
- Clean platinuim/nichrome wire by dipping in concentrated HCL
- Dip into the sample
- Place the loop into Blue bunsen burner
why do we get different colours in the flame test
Electrons in the shells move to higher energy levels as they absorb energy from the flame. When they drop back down to lower energy level, they release energy in the form of light. The colour depends on the wavelength of light energy transmitted.
why do some ions not have a colour
When some electrons drop back down to lower orbitals, the energy emitted may not have a wavelength in the visible light part of the electromagnetic spectrum, which explains why not all atoms and ions produce a colour in the flame test.
what colour does lithuim form
crimson
what colour does soduim form
yellow-orange
what colour does pottasuim form
Lilac
what colour does Rubiduim form
Red
What colour does Caesuim form
Blue
what colour does Berylluim form
No colour
what colour does magnesuim form
No colour
what colour does calcuim form
Brick Red
what colour does Strontuim form
Red
what colour does Baruim form
green
characteristics of Fluorine
- Yellow Gas
- Toxic
- Extremely Reactive
Characteristics of Chlorine
- Green Gas
- Very Reactive
- Toxic
Characteristics of Bromine
- Orange Liquid
- Very Reactive
- Toxic
Characteristic of Iodine
- Grey Crystal
- Reactive
- Toxic
- Can easily turn into purple vapour upon heating
what happens to MP/BP as you go down the group & why for G7
- Increase as you go down the group
- As you go down the group the number of electrons increase
- Also the molecule gets larger as you go down the group
- Due to these 2 factors there is a greater instantaneous dipole induced dipole force
- Therefore it will have stronger London Forces
what happens to electronegativity as you go down the group and why for G7
- The electronegativity decreases
- This is due to an increase in atomic radii which means that the outer electrons are further from nucleus
- This means that the incoming electron will experience more shielding.
what happens to reactivity as you go down the group and why for G7
- The reactivity decreases as you go down the group
- As you go down the group the atoms become larger so outer electron are further away and therefore more shielding for incoming electrons
what is the solubility of G7 in water like
- Since water is polar & G7 aren’t they aren’t able to dissolve fully
- Fluorine reacts violently
- The other halogens dissolve in water to some extent
what do the solutions of halogens dissolved in water look like
- Cl : pale green at top & clear aqueous layer at bottom
- Br: Orange at top and clear aqueous layer at bottom
- I : Brown at top & clear aqueous layer at bottom
what is the solubility of halogens in cyclohexane like
- They are both polar and so they dissolve due to london forces being attracted to each other
what do the solutions of halogen being dissolved in cyclohexane look like
- CL: Pale green at top and clear aqueous layer at bottom
- Br: Orange at top & clear aqueous layer at bottom
- I: Purple at top & cleat aqueous layer at bottom
what can displacement reaction of halogens indicate
Their reactivity
when NaBr is added to the cyclohexane & chlorine solution what is the colour change
Pale green to orange
when NaI is added to cylohexane solution containing chlorine what is the colour change
Pale green to purple
when NaI is added to cyclohexane and Bromine solution what are the colour changes
Brown to purple
what happens during the reaction between G1 + G7
the group 1 become oxidised as it goes from 0 to +1
what happens during the reaction between G2 + G7
the group 2 becomes oxidised as it goes from 0 to +2
what is a disproportionation reaction
reaction where the same species is oxidised & reduced
when can this be seen specifically
reaction of Chlorine with:
1. water
2. Cold alkali
3. Hot alkali
what is the equation of the reaction of Chlorine with water
Cl2(g) + H2O(l) ⇌ HCl(aq) + HClO (aq)
what is the equation of chlorine with cold alkali (15 degrees)
Cl2(g) + 2NaOH(aq) → NaCl(aq) + NaClO (aq) + H2O(l)
what is the equation of chlorine with hot alkali (70 degrees)
5Cl2(g) + 6NaOH(aq) → 5NaCl(aq) + NaClO (aq) + 3H2O(l)
what happens to oxidising power of halogens as you go down group & why
- Decrease
- This is due to the larger radii as you go down the group which causes sheilding and further distance from nucleus means it can’t attract an incoming electron
- They are known as oxidising agents
what happens to reduction ability of halides as you go down the group and why
- Increases
- This is because it gets easier to donate an electron due to weak force of attraction between positive nucleus & negative electron
what is the equation between sulphuric acid & chloride ions and what is the observation
- NaCl + H2SO4 = NaHSO4 + HCl
- The HCL can be seen as a misty white fume
what are the 2 reactions of bromine with sulphuric acid, and why it happens as well as the observation made
- H2SO4 + NaBr = HBr + NaHSO4
- 2HBr + H2SO4 = SO2 + Br2 + 2H2O
- The bromine in HBr is sufficiently strong reducing agent to reduce sulphuric acid into sulphur dioxide while being oxidised itself into Bromine gas
- The bromine gas can be seen as a redish-brown gas
what is the first reaction of iodide with sulphuric acid,
- H2SO4 + NaI = HI + NaHSO4
what is the second reaction of iodide with sulphuric acid, why it happens and the observation
- 2HI + H2SO4 = I2 + SO2 + H2O
- Formed due to the concentrated sulphuric acid oxidising the HI into Iodine and reducing itself to sulphur dioxide
- The iodine can be seen as a purple vapour
what is the third reaction of iodide with sulphuric acid, why it happens and the observation
- 6HI + H2SO4 = S + 3I2 + 4H2O
- The concentrated sulphuric acid oxides the HI to iodine and is reduced to to sulphur
- This can be seen as a yellow sold
what is the fourth reaction of iodide with sulphuric acid, why it happens and what is the observation
- 8HI + H2SO4 = H2S + 4I2 + 4H2O
- The concentrated sulphuric acid is reduced to hydrogen sulphide
what is formed when hydrogen halides are ionised in water
form acidic solution
what is the general equation for hydrogen halide with water
HX + H20 = H3O+ + X-
what is the test for halide
- dissolve in nitric acid
- add silver nitrate to form precipitate
what is the general equation for halide with silver nitrate
AgNO3 + NaX = AgX + NaNO3
what colours precipitates to halides form
chlorine = white
bromine = cream
iodine = yellow
what is another test for halides
AgCl: precipitate dissolves to give a colourless solution
AgBr: precipitate is almost unchanged using dilute ammonia solution, but dissolves in concentrated ammonia solution to give a colourless solution
AgI: precipitate is insoluble in ammonia solution of any concentration
what is the general equation of the ammonia test with halides
AgX + 2NH3 = Ag(NH3)2 + X-
what is ammonia test
- Add NaOH and gently warm
- Test the gas produced by holding near damp litmus paper
- turns blue
- smells like bleach
test for sulphates
- add HCL
- Add baruim chloride
- form white precipitate
test for carbonate ions
- Add HCL
- Causes fizzing and forms CO2
- gas is collected and bubbled through lime water
- Turns cloudy / white precipitate
test for nitrate ions
A
- Add HCL
- Causes fizzing and forms CO2
- gas is collected and bubbled through lime water
- Turns cloudy / white precipitate