A3 inorganics Flashcards by sarah pearson

what are group 2 elements?

alkaline earth metals.
with 2e- in outer shell.
in s block.
M2+ ions.

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what is the structure and bonding of group 2 elements?

giant metallic structures with metallic bonding.

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what is the reactivity of group 2 elements?

MORE reactive down the group as atomic radius decreases down the group.

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what type of solution is formed when group 2 elements react with H2O?

alkaline solutions.

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what data is considered when working out group 2 reactivity?

ΔHat (atomisation), which represents overcoming metallic bonding.
1st and 2nd ionisation energy to form 2+ ion.

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what is the reactivity of group 2 elements in GCSE terms?

atoms get bigger down the group.
outer shell electron further away from nucleus.
attraction to nucleus is weaker.
e-‘s are easier to lose.
MORE reactive down the group.

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what is the reactivity of group 2 elements in A-level terms?

STRONGER REDUCING AGENTS down the group.
decreasing sum of 1st and 2nd ionisation energies.
decreasing metallic bonding strength.

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how do group 2 elements react with oxygen? what type of reaction?

2M(s) + O₂(g) > 2MO(s)

solid as ionic bonding = high MP.
REDOX as M> M²+ + 2e-
O₂ + 4e- > 2O²-

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what is the charge of all group 2 elements in reactions?

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when Mg reacts with oxygen what is observed?

bight white light & white powder

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how do group 2 elements react with chlorine? what type of reaction?

M(s) + Cl₂(g) > MCl₂(s)

REDOX as M > M²+ + 2e-
Cl₂ + 2e- > 2Cl-

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how do group 2 elements react with hydrochloric acid? what type of reaction?

M(s) + 2HCl(aq) > MCl₂(aq) + H₂(g)

H₂(g) = fizzing.
MCl₂ most group 2 compounds are colourless.
REDOX as M > M²+ + 2e-
2H+ + 2e- > H₂

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how do group 2 elements react with water? what type of reaction?

M(s) + 2H₂O(l) > M(OH)₂(?) + H₂

REDOX as M > M²+ + 2e-
H in H₂O gained e- to form H₂.

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what is the solubility of group 2 elements in the compound M(OH)₂?

Mg = X (s)
Cu = sparingly (aq then s)
Sr = soluble (aq)
Ba = soluble (aq)

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how do group 2 elements react as oxides in water/acid? what type of reaction?

MO(s) + H₂O(l) > M(OH)₂(?)
O²- + H₂O > OH- + OH-

O²- = base as H+ acceptor
H₂O = acid as H+ donor

acid-base reaction.

this reflects how they act and behave NOT how they always act.

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what is the use of group 2 compounds in agriculture?

Ca(OH)₂ = slaked lime.
neutralised acidic salts.

what is the use of group 2 compounds in antiacids?

Mg(OH)₂
Ca(HCO₃)₂
treat acid reflux.

what is the use of group 2 compounds in refractory bricks?

heat resistant bricks.
CaO(s).
building:
> ovens.
> khilms.
> furnaces.

ionic bonding = very strong bonding.

what is the formula of group 7 elements?

F₂
Cl₂
Br₂
I₂

what are the states of the group 7 elements?

fluorine = gas
chlorine = gas
bromine = liquid
iodine = solid

what are the pure colours of group 7 elements?

fluorine = v-pale yellow
chlorine = pale green
bromine = brown
iodine = dark grey

what are the aq colours of group 7 elements?

fluorine = N/A
chlorine = colourless
bromine = yellow/orange
iodine = brown

what are the organic colours of group 7 elements?

fluorine = N/A
chlorine = colourless
bromine = red
iodine = purple

when adding I₂ to a test tube of cyclohexane what colours would you see?

cyclohexane layer = purple as I₂ organic.
I₂(aq) = brown.

what is the reactivity of group 7 elements?

F₂ most reactive & I₂ least reactive - although F-F is strongest - F gains e- more easier > as smallest atomic radius & least electron shielding. "F₂ is the strongest oxidising agent" as it takes e- from other things.

what is the group 7 redox reaction between Cl₂ and Br₂?

Cl₂(aq) + 2NaBr(aq) > Br₂(aq) + 2NaCl(aq) Br (-1) oxidised to Br₂ (0) Cl₂ (0) reduced to Cl (-1) Cl STRONGER OXIDISING AGENT than Br (more reactive).

what colours would be observed in this reaction Cl₂(aq) + 2NaBr(aq) > Br₂(aq) + 2NaCl(aq)?

a layer of extra organic Br₂ = red. a yellow layer of Br₂ + NaCl

what is the reaction when Cl₂ disproportionates with water?

Cl₂ + H₂O >< HCl + HClO HCl = strong acid HClO = weak chloric (I) acid// disinfectant

what is the reaction when Cl₂ disproportionates with an alkali?

Cl₂ + 2NaOH >< NaCl + NaClO + H₂O NaClO = bleach// sodium chlorate(I)

what is the gas test for hydrogen?

lit splint > squeaky pop 2H₂ + O₂ > 2H₂O combustion of H₂

what is the gas test for oxygen?

glowing splint > relights wood + O₂ > charcoal + smoke etc.

what is the gas test for carbon dioxide?

bubble through limewater > turns cloudy/ white ppt CO₂(aq) + Ca(OH)₂(aq) > CaCO₃(s) + H₂(l) if add even more CO₂ = ppt disappears CO₂(g) + H₂O(l) + CaCO₃(s) > Ca(HCO₃)(aq)

what is the gas test for chlorine?

bleaches damp blue litmus paper = turns white Cl₂ + H₂O >< HCl + HClO HCl = turns red HClO = Cl(+1) takes e- from litmus, causing loss of colour.

what is the gas test for ammonia?

turns damp red litmus paper blue NH₃ + H₂O > NH₄+ + OH- NH₃ = base as H+ acceptor OH- + alkali

what is the ion test for ammonium?

1. add NaOH & warm. 2. test gas for ammonia. NH₄+ + OH- > NH₃ + H₂O NH₃ + H₂O > NH₄+ + OH- red >>>>>>>>blue

what is the ion test for carbonate (CO₃2-/HCO₃-)

1. add dilute acid (HNO₃) 2. bubble gas through limewater

what is the ion test for sulphate (SO₄2-)?

1. test & rule out carbonate using HNO₃ but NOT H₂SO₄ (important to prevent BaCO₃ appearing as a false positive) 2. then add BaCl₂ Ba2+(aq) + SO₄2-(aq) > BaSO₄ (s) = white ppt

what is the ion test for halides?

1. test for and rule out CO₃2- & SO₄2- (both AgCO₃ and Ag ₂SO₄ are white ppt = false positives). use HNO₃ NITRIC ACID 2. then add AgNO₃(aq) 3. then add, NH₃(aq) Ag+(aq) + X-(aq) > AgX(s) = ppt

what is the colours of the ppt for the halide ion test?

Cl- = white (ppt disappears with dilute NH₃) Br- = cream (ppt only disappears if NH₃ is concentrated) I-+ yellow (never disappears)