Tuesday, October 23, 2007
hi all. =) here's help if you can't rmb transition element colours! =)
im sure everyone know the ROYGBIV colours of the rainbow. so now, first reverse it and you get
VIBGYOR
then from our notes, you can see the different oxidation the element has, which is basically just 6 numbers of 2 3 4 5 6 7.
for Vn we have just 5 different compounds. so you label the compound under their respective colours with their oxidation state.
you get
V I B G Y O R
2 0 4 3 5 0 0
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do it for the first 3 rows.
V I B G Y O R
2 0 4 3 5 0 0
7 0 5 6 0 0 3 2
0 0 2 3 61 62
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first row is vandium, then maganese and lastly chromium. oxidation state four is missing from manganese cos theres no black in the colour. but its obvious MnO2 is black so its ok. pink isnt there aso but its near red so put it after red. 61 62 means tat one chromium atom in CrO42-. two chromium in Cr2O72-.
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of cos this is only for all the H20 ligands.
then next you have the others. just rmbing those on top already clear more than half of it.
now you arrange it by the ligands attached to it.
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theres only 3 different ligands. namely NH3, Cl, CN
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NH3
[Cr(NH3)6]3+ YELLOW
[Co(NH3)6]2+ BROWN
[Co(NH3)6]3+ DARK BROWN
[Ni(NH3)6]2+ BLUE
[Cu(NH3)4]2+ DARK BLUE
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note tat cobalt 2+ and 3+ is brown and DARK brown respectively, and the order follows for nickel and copper. chromium is naturally yellow so its yellow the Cr compound.
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CL
[CuCl4]2- YELLOW
[CoCl4]2- BLUE
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just rmb they exchange colour. everyone know tat copper is blue. so if you rmb cobalt is blue, you would naturally rmb tat cobalt is yellow. like how chlorine is a yellowish greenish gas.
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CN
[Fe(CN)6]4- YELLOW
Fe(CN)6]3- ORANGE RED
[Ni(CN)4]2- YELLOW
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for Fe, rmb tat Fe2+ is greenish, so you associate the compound to be yellow( like how yellow and green go together) then Fe3+ is yellow, so you associate the compound with orange red)
rmb tat V I B G Y O R. so start off Fe2+ with green, and it follows tat its compound is yellow. since Fe3+ is yellow too, it also follows tat its compound is orange-red. (tats one colour bye the way.)
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then for the last 3 water ligands attach to Co Ni and Cu.
Cobalt pink
Nickel green
Copper blue.
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AND TATS IT! =)
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you've just memorised the entire transition table! =) of cos this way of memorizing isnt without flaws. you have to count the oxidation state everytime you see the compound. but long enough it comes to you very quickly.
i hope this helps. =)
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i memorise in around 15mins. hehe
and now im running a fever. -.-
- and check this out.
it works both ways. its all in the mind.
my retrospect;
9:01 PM
