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[Y1] Inorganic Chemistry > Group 17 elements > Flashcards

Group 17 elements Flashcards

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1
Q

what is the alternative name for group 17?

A

the halogens

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2
Q

what is the general configuration of group 17?

A

[X]ns2np5

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3
Q

why do group 17 have high ionisation energies?

A

outer electrons feel strong nuclear charge

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4
Q

ionisation energy of group 17 __________ down the group

A

decreases

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5
Q

electron affinities of group 17 are ____

A

high (very exothermic)

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6
Q

why is the electron affinity of Cl higher than F?

A

capturing an additional electron results in additional e- - e- repulsions

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7
Q

how are the halogens found naturally?

A
  • Mainly found in the form of halide ions in solids or solution.
  • Too reactive to be found naturally in elemental diatomic form, i.e. X2.
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8
Q

F- is more abundant on earth than Cl- but sea is salty with chlorides (mainly), not fluorides. Why?

A

Fluorides are less soluble. Small anion favours high lattice (dissociation) enthalpy (endothermic) which dominates over hydration enthalpy (exothermic).

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9
Q

why is the extraction of fluorine very difficult?

A

Oxidation has a very negative potential (unfavourable):
Requires lots of energy (Eθ = -2.87 V)

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10
Q

what is the appearance of experimental fluorine?

A

Pale yellow gas at standard conditions.

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11
Q

how can Cl2 be obtained (extracted)?

A

by electrolysis of chloride solutions, e.g. aqueous NaCl.

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12
Q

how are Br and I extracted?

A

obtained chemically with a simple displacement

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13
Q

what is the appearance of chlorine?

A

gas at room temperature – pale yellow/green colour

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14
Q

what is the appearance of elemental bromine?

A

Orange-brown liquid at standard conditions

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15
Q

what is the appearance of elemental iodine?

A

Grey solid under ambient conditions, but due to sublimation, gives off purple/violet vapours.

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16
Q

melting and boiling point of group 17 _________ down the group

A

increase

17
Q

why do the melting and boiling points of group 17 increase down the group?

A

Increased size of elemental diatomics leads to greater van der Waals forces (London dispersion – due to there being more electrons) that hold the molecules tighter to each other.

18
Q

are group 17 polar or non-polar?

A

non-polar

19
Q

what does HOMO stand for?

A

highest occupied molecular orbital

20
Q

what does LUMO stand for?

A

lowest unoccupied molecular orbital

21
Q

what is planks equation?

A

E=hv or E=hc/λ

22
Q

what is the colour of transmitted light for F2, Cl2, Br2 and I2?

A

F2: very pale yellow (absorbing highest-energy light with lowest wavenlength)
Cl2: green
Br2: red/brown
I2: purple (absorbing lowest energy light)

23
Q

define bond enthalpy?

A

the energy needed to break one mole of a covalent bond to produce individual atoms, starting from the original substance in the gas state, and ending with gaseous atoms

24
Q

which halogen doesn’t fit the trend of bond enthalpies? why?

A
  • Fluorine
  • bond is weaker than expected since due to the atom’s small size, non-bonding electrons are close to bonding electrons and repel them weakening the F-F bond.
25
Q

what is the appearance of solid aluminium chloride (AlCl3)?

A

sheet-like layered structure with cubic close-packed chloride ions

26
Q

what is the appearance of liquid/gaseous aluminium chloride (AlCl3)?

A

exists in dimeric form – Al2Cl6 (except high temp. vapour where it monomerises to AlCl3).

27
Q

what is the general equation for the silver halide test?

A

Ag+(aq) + X-(aq) –> AgX(s/aq)

28
Q

what colours are formed by the first 4 silver halides?

A

AgF: soluble
AgCl: white
AgBr: off-white
AgI: yellow

29
Q

what happens to the first 4 silver halides in the presence of ammonia?

A

AgF: (no precipitate formed)
AgCl: dissolves if dilute & conc NH3 solution
AgBr: partially soluble in conc. NH3 solution
AgI: insoluble in conc. NH3 solution

30
Q

what is the equation of AgX and NH3?

A

AgX(s) + 2NH3(aq) <–> [Ag(NH3)2]+(aq) + X-(aq)

31
Q

what is the equation for the copper(I) halide test?

A

2Cu2+(aq) + 4I-(aq) –> 2CuI(s) + I2(Aq)

32
Q

what are oxyhalides?

A

Compounds where both oxygen and halogen atoms are attached to another element

33
Q

what is a disproportination reaction?

A

A specific type of redox reaction where a single species is simultaneously oxidised and reduced to form two different products

34
Q

what is the disproportionation reaction for chloric(III) acid?

A

2HClO2 –> HClO + HClO3

[Y1] Inorganic Chemistry (7 decks)

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