4.1 Flashcards

1
Q

what does a group 2 element look like

A

when pure a bright silvery solid
exposed in air it appears dull as it combines with oxygen

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2
Q

what is the trend in ionization energy of group 2 metals

A

decreases down the group

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3
Q

why does ionization energy decrease down group 2

A

each quantum shell added energy of outermost electron increases
atomic radius increases so weaker force from nuclei increased shielding

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4
Q

what is the trend in group 2 elements for reactivity and why

A

increases down the group as less energy is needed to remove an electron

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5
Q

what would be observed if you burn magnesium in air

A

bright flame
formation of a white solid

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6
Q

how is barium often stored and why

A

under oil
so it cannot react with oxygen or water vapor as it is extremly reactive

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7
Q

what is the general equation for group 2 metals reacting with oxygen

A

2M(s) + O2(g) -> 2MO(s)

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8
Q

as you go down group 2 you can tell reactivity increases as they react with water because…

A

increasing effervescence

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9
Q

what is the general equation for the reaction of a group 2 metal with water

A

M(s) + 2H2O(l) -> M(OH)4(aq) + H2(g)

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10
Q

what is the trend in solubility of group 2

A

increases down the group

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11
Q

what is the trend in alkalinity of solutions formed of group 2

A

increases down the group

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12
Q

why does the trend in alkalinity of solutions formed of group 2 increase down the group

A

higher solubility therefor more OH- ions present in solution

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13
Q

what is the test for carbon dioxide

A

limewater goes cloudy
white precipitate formed

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14
Q

what do all group 2 oxides & hydroxides form when they react with acids

A

salt & water

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15
Q

what is the trend in solubility of group 2 sulfates

A

decreases down the group

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16
Q

what is the test for the presence of sulfate ions in an aqueous solution

A

add dilute nitric acid or hydrochloric acid
add solution containing barium ions
white precipitate barium sulfate formed

17
Q

why are dilute nitric acid or hydrochloric acid added in the test for sulfate ions

A

to prevent barium carbonate from forming as a white precipitate

18
Q

what is thermal stability

A

measure of the extent to which a compound decomposes when heated

19
Q

why do group 2 nitrated & carbonates have lower thermal stability than group 1

A

cation charge greater than group 1 therefor group 1 ions are less polarising so need more heating tham group 2

20
Q

what happens to group 2 nitrates & carbonates when they are heated

A

they decompose

21
Q

what do all nitrates of group 1 and 2 look like

A

white solid

22
Q

what is observed when group 1/2 nitrates decompose

A

decompose to nitrites or oxides
nitrogen dioxide (brown gas) is produced

23
Q

what do all group 1/2 carbonates look like

A

white solids

24
Q

what happens to group 1 & 2 carbonates when they are heated

A

don’t decompose
or
decompose to oxides and give off carbon dioxide

25
what are the problems with flame tests
many compounds contain sodium impurities which will mask other colours subjective to different levels of colour vision
26
what is the flame test for lithium Li+
red
27
what is the flame test for sodium Na+
yellow/orange
28
what is the flame test for potassium K+
lilac
29
what is the flame test for rubidium Rb+
red/purple
30
what is the flame test for caesium Cs+
blue/violet
31
what is the flame test for beryllium Be2+
no colour
32
what is the flame test for calcium Ca2+
brick red
33
what is the flame test for magnesium Mg2+
no colour
34
what is the flame test for strontium Sr2+
crimson red
35
what is the flame test for barium Ba2+
(apple) green
36
what is the flame test for copper
blue/green
37
what is the test for aqueous ammonium ions
add sodium hydroxide solution & warm ammonia gas produced