Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Problem of the Week Archive => Topic started by: Borek on March 19, 2012, 11:29:34 AM
-
This one is completely different. I remember answering this question in the past, but I don't remember where I got it from.
Add 4 more substances to the list:
H2, Li, He, Be, N2, B, O2, C, F2, Na, Ne, Mg...
-
P Al S Si :-X
-
P4, Al, S8, Si?
Basically UG but in standard states?
-
Neither is what I expected. Can you explain the logic behind your answer?
-
This is borderline guess, but the first, third, fifth, etc. elements progress along the periodic table and so do the second, forth, sixth, etc elements.
-
I see.
OK, it is not the right answer :P
-
H2, Li, He, Be, N2, B, O2, C, F2, Na, Ne, Mg...
I took the "math sequence" path-I may be way out but - I'll give this a try:
first I put the elements next to its atomic number- Then I found what do I need to add or subtract (in atomic number units) to get the next element:for example H is 1, plus 2 gives Li; Li is 3, minus 1 gives He, and so on:
H2--1 (+2)
Li---3 (-1)
He--2 (+2)
Be--4 (+3)
N2--7 (-2)
B---5 (+3)
02--8 (-2)
C---6 (+3)
F2--9 (+2)
Na--11 (-1)
Ne--10 (+2)
Mg--12 (?)
Then I studied the sequence of signs:
(+ - +) ( + - +) (- + +) (- + ?) ( ? ? ?) ( ? ? ?) and I continued the sequence as follows:
(+ - +) ( + - +) (- + +) ( - + +) (+ - +) (+ - +).
Lastly the number sequence:
(2 1 2) (3 2 3) (2 3 2) (1 2 ?) ( ? ? ?) (? ? ?) I continued the sequence as:
(2 1 2) (3 2 3) (2 3 2 ) (1 2 1) (2 1 2) (3 2 3)
so putting all together: this will the completed sequence:
( +2 -1 +2) (+ 3 -2 +3) ( -2 +3 +2) (- 1+ 2+ 1) (+2 -1 +2) ( +3 -2 +3)
so completing the sequence on the top:
H2--1 (+2)
Li---3 (-1)
He--2 (+2)
Be--4 (+3)
N2--7 (-2)
B---5 (+3)
02--8 (-2)
C---6 (+3)
F2--9 (+2)
Na--11 (-1)
Ne--10 (+2)
Mg--12 (+1)
Al ---13 (+2)
P4----15 (-1)
Si---14 (+2)
S8----16
and I wrote them in standard states as all are on the list:so Al, P4, Si, S8 is my answer ;D
-
I think I got it after trying out many strange approaches for 20min...Cl, K, Ar, Ca?
Highlight text for explanation (possible spoiler): They are following 'gas, solid, gas, etc.' pattern on the periodic table going 1st gas, 1st solid, 2nd gas, 2nd solid so on. Very cool!
-
you' re right =) I think you got it- real cool!
-
This question is definitely a different one, keen to see the answer.
And that's a lot of typing Ann1234 :o
-
I think I got it after trying out many strange approaches for 20min...Cl, K, Ar, Ca?
You are on the right track - but still not there.
-
Cl2, Al, Ar, Si?
-
Cl2, Al, Ar, Si?
Yep :D
-
Oops, I see where I made the silly mistakes.