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EDEXCEL Chemistry a level > inorganic chemistry and the periodic table > Flashcards

inorganic chemistry and the periodic table Flashcards

1
Q

group 7 name

characteristics

A

halogens

diatomic molecules

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2
Q

Why are fluorine and astatine generally ignored out of the halogens?

A

Fluorine behaves differently to rest of elements and astatine only exists as a radioactive isotope

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3
Q

trend in state down group 7

A

gas to solid

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4
Q

trend in mp/bp down group 7

A

increases

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5
Q

trend in electronegativities down group 7

A

decreases

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6
Q

how London forces are formed between diatomic halogen molecules

A

identical atoms mean pair of electrons are shared equally between (therefore on average aren’t polar). fluctuations in charge result in a temporary dipole. if molecule on left forms an instantaneous dipole, another dipole is induced on right, producing a force of attraction (instantaneous dipole-induced dipole attraction).

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7
Q

trend in bond strength between atoms in group 7

A

increases as number of electrons in molecules increases

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8
Q

properties determining electronegativity of an atom

A

nuclear charge
distance between nucleus and bonding pair
shielding effect

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9
Q

trend in reactivity down group 7

A

decreases down group w electronegativity

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10
Q

roles of halogens in reactions

A

act as oxidising agents, gaining electrons to form a negative ion.
due to high electronegativity

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11
Q

most vigorous reactions between group 1 and 2 metals with halogens

A

elements at bottom of groups 1 and 2 with elements at top of group 7

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12
Q

products of group 1 and 2 metals w halogens

reaction process

A

salts
ionic salts that are usually white
redox reactions in which halogen acts as oxidising agent

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13
Q

oxidation numbers in reaction between group 1 and 2 metals w halogens

A

halogen decreases from 0 to -1

metal increases from 0 to +1/+2

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14
Q

way to make halide colors more distinctive

A

add an organic solvent such as cyclohexane as halogens are more soluble than in water so will dissolve in upper layer where colors will be more distinctive

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15
Q

color of chlorine / bromine/ iodine

A

Cl» green
Br» orange brown
I&raquo_space; purple

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16
Q

why is chlorine most reactive of halogens?

A

atom is smaller so outer electrons are closer to nucleus

smallest amount of shells and so shielding is reduced

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17
Q

disproportionation

A

a reaction in which one element undergoes both oxidation and reduction simultaneously.

18
Q

reaction of chlorine with water

A

forms chloric acid and hydrochloric acid

Cl2 +H2O&raquo_space; HCl + HCLO

19
Q

reaction of chlorine with cold alkali

A

forms salts of the chloric and hydrochloric acids
sodium chloride and sodium chlorate 1
eg, 2NaOH + Cl2&raquo_space; NaCl + NaClO + H2O

20
Q

sodium chlorate use

A

disinfectant, used as main ingredient of bleach.

21
Q

reaction of chlorine with hot alkali

A

forms salts of chloride and chlorate 5

eg, 6NaOH + 3Cl2&raquo_space; 5NaCl + NaClO3 + 3H2O

22
Q

how do halide ions differ from halogen molecules in their reactions

A

halide ions act as reducing agents in reactions while halogen molecules act as oxidising agents.

23
Q

reducing power of halide ions as you go down the group

A

increases

24
Q

oxidising power of halogen molecules as you go down the group

A

decreases

25
Q

sulfuric acid role in reactions

A

can act as an oxidising agent and an acid
partially ionising : H2SO4&raquo_space; H+ + HSO4
HSO4-&raquo_space; H+ + SO42-

26
Q

3 possible reaction products with sulfuric acid

A

sulfur dioxide
sulfur
hydrogen sulfide

27
Q

observation and products in reaction of NaCl w conc. H2SO4

A

misty fumes and hydrogen chloride is formed

28
Q

observation and products in reaction of NaBr w conc. H2SO4

A

misty fumes, brown fumes and colourless gas w choking smell

HBr, Br2, SO2

29
Q

observation and products in reaction of NaI w conc. H2SO4

A

misty fumes, purple fumes/black solid, colourless gas w choking smell, yellow solid, colourless eggy gas
HI, I2, SO2, S, H2S

30
Q

role of sulfuric acid in halogen reactions

A

NaCl» behaves as an acid as Cl has low reducing power
NaBr» is reduced as Br has more reducing power
NaI&raquo_space; greater reducing power of iodide ions reduces sulfuric acid fully

31
Q

equation of reaction of sulfuric acid w sodium chloride

A

NaCl + H2SO4&raquo_space; NaHSO4 + HCl

32
Q

equation of reaction of sulfuric acid w sodium bromide

A

made up of 2 redox reactions:
2Br-&raquo_space; Br2 + 2e- // H2SO4 + 2H+ +2e-&raquo_space; 2H2O + SO2
2HBr + H2SO4&raquo_space; 2H2O + SO2 + Br2

33
Q

equation of reaction of sulfuric acid w sodium iodide

A

3 redox reactions occur, put together

6HI + H2SO4&raquo_space; 4H2O + S +3I2

34
Q

precipitate colour of halogens in addition of silver nitrate

A

Cl&raquo_space; white
Br» cream
I» yellow

35
Q

Which halogen does dilute aqueous ammonia test for

A

bromide and iodide ions as they are insoluble

36
Q

which halogen does concentrated aqueous ammonia test for

A

Iodide ions as they are insoluble

37
Q

Why do halide precipitates dissolve in the ammonia solutions?

A

formation of a complex ion

38
Q

hydrogen halides reaction with water

A

form colourless, acidic solutions

39
Q

why is the formation of hydrofluoric acid from hydrogen fluoride and water reversible?

A

because it is a weak acid

40
Q

reaction of water and hydrogen iodide

A

forms hydriodic acid

41
Q

equation for reaction of HCl with water

A

H2O + HCl&raquo_space; H3O + Cl-

42
Q

reactions of hydrogen halides with ammonia gas

A

form white ionic solid salts

eg, NH3 + HCl&raquo_space; NH4Cl

EDEXCEL Chemistry a level (12 decks)

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