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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Beanyboy on April 10, 2018, 08:48:02 PM

Title: The nature of matter
Post by: Beanyboy on April 10, 2018, 08:48:02 PM
How do we explain the dramatic change in the state of matter between Carbon and Nitrogen -neighbours on the periodic table? One is a solid, the other a gas.
Title: Re: The nature of matter
Post by: Borek on April 10, 2018, 08:50:56 PM
Sounds like a homework question, have you read the forum rules?
Title: Re: The nature of matter
Post by: Arkcon on April 11, 2018, 01:56:55 AM
Is there anything about being next to each other on the periodic table that means they should have similar properties?

Can we use the periodic table to predict properties of the elements?

What makes an element occupy a different place on the periodic table?  Which is just asking why there are different elements.  But still -- what's different between the two?

These are useful questions you can ask yourself, and answer with information from your textbook and class notes, to help you learn the answer.
Title: Re: The nature of matter
Post by: Beanyboy on April 11, 2018, 10:19:49 AM
I'm a 56 year old Irish teacher - though not of any Science, so no homework involved here. Nothing in my textbook "Modern Chemistry", helps with this.

A mole of carbon is 12 grams of graphite and is approximately the volume of the lead in my pencil.A mole of nitrogen is about 14 grams, but it occupies a space of a litre, and it is a gas. Puzzling to me why we see
(a) extraordinary rise in volume occupied and (b) why the change in matter.

If the volume change helps explain the change in matter, how do we account for the dramatic change in volume? After all, a mole of oxygen, nitrogen's neighbour, has the SAME volume as  a mole of nitrogen, and yet the net change in the fundamental number of particles between 1 mole nitrogen, to 1 mole oxygen, is precisely the same as net difference between 1 mole carbon, 1 mole nitrogen.

Thanks for your patience in advance.
Title: Re: The nature of matter
Post by: Beanyboy on April 11, 2018, 10:25:35 AM
Incidentally, I note that phosphorus and arsenic are in the same group as nitrogen. Using the table to predict their physical properties might lead me to believe they are gases too, but of course, they're not.
Title: Re: The nature of matter
Post by: wildfyr on April 11, 2018, 10:28:11 AM
What is the other major property the periodic table tells us aside from atomic weight and atomic number? And how might this property affect how an element interacts with itself in elemental form?

Hint: 8
Title: Re: The nature of matter
Post by: Borek on April 11, 2018, 11:39:41 AM
As it was already signaled several times: the property of the elements that is used as a key for arranging elements in the periodic table has (almost) no simple connection with their physical properties.

To use a (poor) analogy: imagine having handful of used crayons. You arrange them (using their colors) as in a rainbow. Does the position of the crayon in the arrangement tell you anything about its length?
Title: Re: The nature of matter
Post by: Beanyboy on April 11, 2018, 12:15:48 PM
As it was already signaled several times: the property of the elements that is used as a key for arranging elements in the periodic table has (almost) nothing to do with their physical properties.

To use a (poor) analogy: imagine having handful of used crayons. You arrange them (using their colors) as in a rainbow. Does the position of the crayon in the arrangement tell you anything about its length?

I'm sorry, but are you saying "This is simply the nature of nature". Is there no explanation to account for the change in the state of matter from carbon to nitrogen? I appreciate your time and patience.
Title: Re: The nature of matter
Post by: Borek on April 11, 2018, 12:47:14 PM
I'm sorry, but are you saying "This is simply the nature of nature".

Well, that's the way it works.

Quote
Is there no explanation to account for the change in the state of matter from carbon to nitrogen?

Using electron structure (or configuration) of atoms of carbon we can explain why it is solid, we can explain - again starting from electron structure of atoms - why nitrogen is gaseous. But these are separate things. There is no continuity that will allow us to say "because of that and that state of matter changes".

To use another analogy (not much better than the previous one) it is like trying to predict whether 11 is divisible by 7 from the fact 10 is divisible by 2 and 5. There is no connection, even if 11 is a neighbor of 10.

In the case of some other elements being neighbors of the same kind as C and N such a continuity exists (for example, several consecutive metals having a higher and higher density as we move to the right), but it is rarely simple.
Title: Re: The nature of matter
Post by: Beanyboy on April 11, 2018, 03:02:22 PM
Really appreciate you taking time out to explain. Thanks.
Title: Re: The nature of matter
Post by: Beanyboy on April 11, 2018, 03:40:03 PM
What is the other major property the periodic table tells us aside from atomic weight and atomic number? And how might this property affect how an element interacts with itself in elemental form?

Hint: 8

So, are you saying that if an element has a full octet, this would affect how it would interact with itself in elemental form and thus contribute to the resultant state of matter?
Title: Re: The nature of matter
Post by: Enthalpy on April 11, 2018, 11:59:53 PM
N2 makes a perfect chemical bond, if you understand it with molecular orbitals. This leaves little possibilities for more interactions. C2 in contrast isn't an excellent combination, with two electrons less, and while this molecule exists as a gas at high temperature, other combinations are energetically more favourable at room temperature, where more atoms are involved - graphite.

This isn't the whole picture. As you go down the so-called periodic table, molecules tend to stick better to an other. This explains why gases use to comprise lighter atoms and solids heavier ones. Or even, heavier atoms tend to make metals, where the molecules are huge - still a different reason.

"Next to an other" in the periodic table does not imply similar properties. Next to rare gases right and left, you have very reactive alkaline metals and halogens. Similar chemical properties are observed within columns instead. This similarity lets suppose compounds with similar chemical formulas exist but is a poor predictor for physical properties.
Title: Re: The nature of matter
Post by: Beanyboy on April 14, 2018, 02:44:49 AM
A mole of carbon is 12 grams of graphite and is approximately the volume of the lead in my pencil.A mole of nitrogen is about 14 grams, but it occupies a space of a litre ...

Isn't more correct to say that a mole of gas occupies about 24 litres, not one 1 litre?
Title: Re: The nature of matter
Post by: Borek on April 14, 2018, 03:41:39 AM
A mole of nitrogen is about 14 grams, but it occupies a space of a litre ...

No idea where you got it from. Volume occupied by 1 mole of gas depends on the pressure and temperature. Google for ideal gas equation.

Quote
Isn't more correct to say that a mole of gas occupies about 24 litres, not one 1 litre?

24 liters at RTP (room temperature and pressure) or 22.4 L at STP (standard TP - although the "standard" part is a bit ambiguous, most definitions are close to 1 atm and 0°C).

Plus, 1 mole of gaseous nitrogen is 28 g, as - especially around RTP/STP - nitrogen comes in diatomic molecules N2.
Title: Re: The nature of matter
Post by: Kalium on April 15, 2018, 09:39:45 AM
There should be a reason for the state changes between similar elements in regards to a couple particles . I can surely see the curious questions beanyboy would naturally come to on the thought .

I feel it's not very scientific to merely state it s the nature of the elements , not that anyone is.

I would probably attribute the changes to valence election numerals, bond types and orbital configurations and even nuances of spin at subatomic interactions for some of the elements then postulate weak nuc forces for some of the solid states of heavier elements.

But don't ask me to postulate beyond that , I'm still learning too
Title: Re: The nature of matter
Post by: Borek on April 15, 2018, 09:50:23 PM
There should be a reason for the state changes between similar elements in regards to a couple particles

Quote
I feel it's not very scientific to merely state it s the nature of the elements , not that anyone is.

I feel like you are missing the point. Not every question has an answer, I already gave examples of such questions.

There is no problem with scientifically explaining properties of carbon and nitrogen based on their electron configuration. Not easy, it requires quantum mechanics, but perfectly doable. Trick is, it doesn't answer the original question. Original question assumed (even if indirectly) there exists a continuity of properties that is a reason behind change from the solid to the gas, and there is no such continuity.
Title: Re: The nature of matter
Post by: Kalium on April 18, 2018, 06:17:52 PM
I understood the point , and I can see the historic view of not having answers to current phenomenon.

I mostly wasn't looking for a particular answer either , I suppose , or not even really , I was stating the unique limited amount of knockdown evidence for states we have , or maybe not even because I've not really read any new or much older material for that matter on it.

It wasn't aimed at anyone . Just an observation of intrigue because of the novelty of the op question . I wasn't even lol asking for an experts opinion , it was subjective lol.


"Trick is, it doesn't answer the original question. Original question assumed (even if indirectly) there exists a continuity of properties that is a reason behind change from the solid to the gas, and there is no such continuity."

I would be very much interested in reading material that proves that the continuity does not exist ....and not to have any pride issues on it , mainly only to see what research has progressed to on it , and if or a limit has been reached for what ever reason and the question abandoned altogether .

There are many questions in science that are not currently possible to begin to answer . Absence of reasons for state changes is not a particular one that sits well with me . ha it's not like I have a choice other wise if it doesn't , it's just that it seems absurd to me subjectively that it would not . It feels closer to a lack of understanding , but again, I'm not well enough versed .

I never intending on disagreements with peers on subjects I've not mastered material. The op question only forces me to imagine question s about the nature as well . Even if the answer is it doesn't have and answer . But that just is not something I have an easy time with personally . I'm more apt to think that it doesn't have an answer yet .

But I may know less , well I can admit openly , I know not much more that anything about it to even decern if it woukd have a pattern or not .

Lol I only found the question one of interest was all .