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Chemistry Year 12 > 4 - Inorganic chemistry and the periodic table > Flashcards

4 - Inorganic chemistry and the periodic table Flashcards

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1
Q

Trend in ionisation energy down group 2?

A
  • decreases as you go down the group
  • atomic radii increases
  • number of shells increases, greater shielding effect.
  • energy of the outermost electrons increases,
  • so ionisation energy decreases down a group.
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2
Q

What type of bonding is present in group 1 and 2 elements?

A

metallic bonding

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3
Q

Trend in metallic bonding down group 1 and 2?

A
  • decreases
  • although nuclear charge increases
  • atomic radius increases
  • distance between the positive nuclei and delocalised electrons increases.
  • shielding effect from inner electron shells also increases
  • force of attraction between positive nuclei and delocalised electrons decreases.
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4
Q

Trend in reactivity down group 2?

A
  • increases
  • although nuclear charge increases
  • atomic radii increases
  • shielding effect increases
  • attraction between nucleus and outer electrons decreases.
  • easier to remove outer electrons, easier to form cations.
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5
Q

group 2 metal + oxygen

A

metal oxide.

  • bright flame
  • high melting points (ionic bonding)

2M + O2 -> 2MO

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6
Q

Group 2 metal + chlorine

A

metal chloride

  • misty fumes
  • white solid

M + Cl2 -> MCl2

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7
Q

Group 2 metal + water (warm)

A

metal hydroxide
- bubbles form
- fizzing
- metal dissolving
- solution heats up
^^(more vigorous, faster, more heat, down the group due to increase in reactivity).
- calcium, white precipitate. (Less precipitate forms down the group)

M + 2H2O(l) -> M(OH)2(aq) + H2

Calcium is exception:
Ca + 2H2O(l) -> Ca(OH)2(s) + H2

calcium hydroxide is only slightly soluble in water, precipitate forms, solution becomes cloudy.

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8
Q

Group 2 metal + water (steam)

A

metal oxide and hydrogen
- bright flame

M + H2O(g) -> MO(s) + H2

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9
Q

What type of reactant is a metal oxide classified?

A

Base

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10
Q

Group 2 oxide + water

A

metal hydroxide

MO(s) + H2O(l) -> M(OH)2(aq)

simplified (no change in Mg2+ ion):

O2- + H2O -> 2OH-

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11
Q

What type of reaction occurs when group 2 oxides AND hydroxides react with dilute acids?

A

BAWS
- neutralisation reaction.

MO + H2SO4 -> MSO4 + H2O

M(OH)2 + H2SO4 -> MSO4 + 2H2O

M(OH)2 + 2HCl -> MCl2 + 2H2O

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12
Q

Trend in solubility of group 2 sulfates down the group?

A
  • decreases down the group.
  • magnesium sulfate soluble
  • calcium sulfate slightly soluble
  • strontium and barium sulfate insoluble.
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13
Q

How is the insolubility of a certain group 2 sulfate used to test for the presence of sulfate ions?

A
  • sample solution is acidified with dilute hydrochloric acid (to remove carbonate impurities).
  • barium chloride solution is added.
  • If sulfate ions are present, the sulfate ions in the solution will react with the barium ions in the BaCl2 to form BaSO4. BaSO4 is insoluble and will show as a white precipitate.
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14
Q

Trends in solubility of group 2 hydroxides down the group?

A
  • increases down the group.
  • magnesium hydroxide has very low solubility in water.
  • barium hydroxide has high solubility in water.
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15
Q

What is the formula for limewater?

A

Calcium hydroxide
Ca(OH)2.
reasonably soluble in water.

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16
Q

What is the test for CO2?

A
  • lime water is used.
  • CO2 reacts to form CaCO3 which is a white precipitate.
  • CaCO3 is insoluble in water
  • limewater turns cloudy.
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17
Q

Trend in thermal stability of group 1 and 2 carbonates and nitrates down the group?

A
  • thermal stability increases down the group.
  • cation size increases
  • polarising ability of the cation on the anion decreases.
  • bond strength increases between cations and anions.
  • thermal stability increases
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18
Q

Do group 1 carbonates decompose?

A

No, except lithium carbonate.

  • group 1 cations have a 1+ charge which means that the polarising ability of group 1 cations are too small.
  • Lithium ion is small enough to have a polarising ability on the carbonate anion.
  • group 1 carbonates are all thermally stable except lithium.
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19
Q

Polarising effect compare between group 1 and group 2 cations

A

group 2 cations have a greater polarising effect because they have a 2+ charge.

the 1+ charge on the group 1 ions means they have a too little charge density to have a polarising ability. (group 1 carbonates cannot decompose except lithium).

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20
Q

What is polarising ability of a cation?

A

The ability of a cation to distort the electron cloud around the anion.

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21
Q

What factors affect polarising ability?

A
  • size of cation charge

- size of cation

22
Q

decomposition of lithium carbonate?

A

Li2CO3(s) -> Li2O(s) + CO2(g)

  • test with limewater (turns cloudy) to see if it has decomposed.
23
Q

What do group 2 nitrates decompose to?

A
  • oxide
  • nitrogen dioxide
  • oxygen
24
Q

What do group 1 nitrates decompose to?

A

Only lithium nitrate:

  • oxide
  • nitrogen dioxide
  • oxygen

other group 1 nitrates:

  • nitrite (III)
  • oxygen
25
Q

What colour is NO2 gas?

A
  • brown gas.
26
Q

what is the formula for nitrate (v)?

A

NO3-

27
Q

what is the formula for nitrate (III)?

A

NO2-

28
Q

Group 1 ion colours?

A
  • Li+ : red
  • Na+ : yellow/orange
  • K+ : lilac
  • Rb+ : red/purple
    Cs+ : blue/violet
29
Q

Group 2 ion colours?

A
  • Mg2+ : no colour
  • Ca2+ : brick red
  • Sr2+ : crimson red
  • Ba2+ : apple green
30
Q

What does lithium and group 2 carbonates decompose to?

A

metal oxide and carbon dioxide

31
Q

Why does a colour show in a flame test?

A
  • electrons absorb energy from the Bunsen flame and move to higher energy levels.
  • ground state to excited state.
  • the electrons immediately fall back to their ground state, releasing energy.
  • if this energy corresponds to radiation in the visible part of the electromagnetic spectrum, a colour is seen.
32
Q

Steps of a flame test?

A
  • use a nichrome wire
  • clean it by dipping in concentrated hydrochloric acid and heat in Bunsen flame.
  • dip clean nichrome wire in solid and put in Bunsen flame.
33
Q

States of group 7 elements at room temp?

A
  • fluorine: gas
  • chlorine: gas
  • bromine: liquid
  • iodine: solid
  • astatine: solid
34
Q

trend in electronegativity down group 7?

A
  • decreases
  • because atomic radius increases due to increasing number of electron shells.
  • nucleus is further away from bonding pair of electrons (distance increases), and shielding effect from inner electron shells increases.
35
Q

Trend in melting/boiling temperatures down group 7?

A
  • increases
  • number of electrons increases
  • stronger London forces between the halogen molecules.
36
Q

Trend in reactivity down group 7?

A
  • reactivity decreases down the group
  • although nuclear charge increases
  • atomic radii increases
  • number of shells increases
  • shielding effect from inner shells increases.
  • so as you go down the group halogen atoms will less easily attract and accept electrons.
37
Q

Reaction of group 1 and 2 metals with halogens? and what type of reaction is this?

A
  • forms salts (metal halides). usually white solids.

- oxidation reaction.

38
Q

halogen and halide displacement reactions. What displaces what?

displacement reactions are redox reactions

A

A more reactive halogen displaces a less reactive halogen from one of its compounds.

reactivity: chlorine > bromine > iodine

  • chlorine displaces both bromine and iodine
  • bromine displaces iodine (not chlorine)
  • iodine does not displace either chlorine or bromine (least reactive out of the three).
  • occurs in aqueous solution
39
Q

observations of halogens in aqueous solution?

A
  • chlorine: colourless
  • bromine: orange/brown
  • iodine: red
40
Q

Why are organic solvents added to halogen halide displacement reactions and observations?

A
  • usually cyclohexane
  • halogens are more soluble in cyclohexane (organic solvent) than in water.
  • when added to the aqueous solution,
  • halogen dissolves in the organic upper layer, where the colours can be more clearly seen.

in organic solvent:

  • chlorine: very pale green
  • bromine: orange/brown
  • iodine: violet
41
Q

What is a disproportionation reaction?

A

It is a reaction where the same element is simultaneously oxidised and reduced.

42
Q

Reaction of Cl2 and water? And what type of reaction is this?

A
  • forms chlorine water and
  • disproportionation reaction
  • Cl2 + H2O -> HCl + HClO
  • chlorine is reduced and oxidised.
  • chlorine dissolved in water kills pathogens in water.
43
Q

Reaction of Cl2 and cold dilute aqueous NaOH solution? And what type of reaction is this?

A
  • forms bleach
  • disproportionation
    Cl2(aq) + 2NaOH(aq) -> NaCl(aq) + NaClO(aq) + H2O(l)
  • sodium chlorate (I) - bleach.
44
Q

Reaction of Cl2 and hot concentrated NaOH solution? And what type of reaction is this?

A
  • substance used in bleaching and as a weed killer.
  • disproportionation
    3Cl2(aq) + 6NaOH(aq) -> 5NaCl(aq) + NaClO3(aq) + 3H2O(l)
  • sodium chlorate (V) - bleach, weed killer.
45
Q

What do you do if asked to predict reactions of fluorine and astatine?

A

treat like the other halogens learnt in this topic.

e.g sodium + iodine -> sodium iodide

sodium + astatine -> sodium astatate (NaAt)

46
Q

How to test for CO3- ions?

A
  • add any dilute strong acid to sample solution
  • fizzing will be seen due to CO2 produced.
  • indicates that carbonate ions are present.

2HCl + Na2CO3 -> 2NaCl + H2O + CO2

2H+ + CO32- -> H2O + CO2

47
Q

How to test for CO2?

A
  • bubble gas through limewater
  • limewater turns cloudy
  • due to calcium carbonate precipitate formed.
48
Q

How to test for SO42-?

A
  • add dilute hydrochloric acid (to remove carbonate impurities).
  • add barium chloride solution
  • If sulphate ions are present, they react with the barium ions to produce barium sulphate.
  • barium sulphate is insoluble in water and will form a dense white precipitate.
49
Q

How do you test for NH4+?

A
  • add warm aqueous sodium hydroxide
  • ammonia NH3 is formed.
  • can be identified by pungent smell, damp red litmus paper turns blue.
50
Q

Test for halide ions?

A
  • add dilute nitric acid (to remove any other anions)
  • add silver nitrate solution
  • cl-: silver nitrate
  • silver bromide
  • silver iodide

Add ammonia solution

  • AgCl: dissolves in ammonia solution to give colourless solution
  • AgBr: insoluble in dilute ammonia solution, dissolves in concentrated ammonia solution.
  • AgI: insoluble in ammonia solution of any concentration.
51
Q

Test for hydrogen halide?

A
  • add ammonia gas
    NH3(g) + HX(g) -> NH4X(g)
  • white fumes produced.
  • turns blue litmus paper red.

Chemistry Year 12 (12 decks)

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